Monday, September 10, 2012

Update for the Week of September 9

As we observed and stated last week, soybeans in Alabama are experiencing the most widespread outbreak of foliage feeding insects of the past 41 seasons. This outbreak has been going on for about three weeks or more. However, some growers are just now discovering the situation. This has led to the most calls and questions that Dr. Tim Reed and I have ever received during one week. I will attempt to summarize the questions and what our responses have been.

Most calls begin with – “I have worms in my soybeans, when do I need to treat and what insecticide do I need to use?”

First of all, in most all fields we are dealing with a mix of soybean loopers (SL), velvetbean caterpillars (VBC), and green cloverworms (GCW). Loopers are statewide, VBC are a significant part of the mix in south and central Alabama while GCW are a large part of the mix in northern areas of the state. Loopers are resistant to pyrethroids, Lannate and all of the older chemistry. Since they are part of the mix statewide, we must go to the newer chemistry (in alphabetical order): Belt 3 oz.; Blackhawk (Tracer) 2 oz.; Intrepid 4-8 oz.; or Steward 7 oz. Prices for Belt, Blackhawk and Steward will be somewhere between $15 and $20 per acre. Intrepid will range from about $7 to $14, depending on the rate used. The 4 oz. rate has been what most growers have chosen due to economics. However, where significant foliage loss has already occurred and worm numbers are high, this 4 oz. rate is not adequate. At least 5 or 6 oz. of Intrepid will be needed.

In addition to worms, most all soybean fields have some level of stink bugs present. None of the worm materials will control stink bugs. Therefore, a pyrethroid or acephate (Orthene or generic) at 0.75 lb./ai must be added. This rate of acephate makes pyrethroids the most economic choice. The majority of our stink bugs are the green or southern green species, which pyrethroids control very well.

Now back to what a threshold is on foliage loss. Depending on the stage of beans, our threshold is 20-30% foliage loss. That does not mean that we wait for that level before treating. We treat in advance when we find worm numbers that will give that level of loss. Also, we must allow 4-5 days for products like Intrepid to control the worms. However, foliage consumption will normally end much sooner. Big factors, which are seldom mentioned in discussing foliage loss thresholds in soybeans, are the amount of moisture available to the crop and the reproductive stage of the beans. Soybeans can compensate at a much higher level when soil moisture is available and we have that statewide at present. Also, soybeans will replace lost foliage when they are still in the blooming stage.

How many worms does it take to cause 20-30% foliage loss? In traditional row beans, where a drop cloth can be used, somewhere between 4 and 8 larvae per row foot will give 20-30% foliage loss. The size of the beans is also a variable here. Due to the good moisture in August, many of our beans are waist high and have lots of foliage. Many of our beans in 2012 are drilled. Therefore, a sweep net is needed to get a measure of worm numbers. I suggest taking 10 sweep samples. Some states recommend treatment when about one larva per sweep is found. I have found in 2012 that it takes about 3 or 4 worms per sweep to cause 20-30% foliage loss. Another factor to consider is how long the worm infestation has been ongoing. In fields I have monitored, the answer is three or more weeks. New worms just keep hatching, so where a subthreshold has been present for 15-20 days, much of the lower canopy has already been consumed by the worms. In this situation a 10% foliage loss can turn into a 30-40% loss in 7 days.

In summary, I feel that our Extension educational program on soybean insects has been very inadequate and we promise to do better beginning with winter meetings. However, growers must also do their part in managing insects in soybeans, especially when they are worth $17-18 per bushel. We do not know what level of insect pressure 2013 will present, but if we plan to stay on top of the insect situation, soybeans will need to be monitored by a trained or experienced person at least weekly during the season, just like we have done in cotton for the last 60 years.

Friday, August 31, 2012

Update for Week of August 26

The cotton insect control season is basically over. I say that realizing that there are a few late maturing fields within the state that may still need a stink bug spray. There are even fewer fields that have high numbers of tarnished and clouded plant bugs present. Where growers are attempting to make a top crop, in fields that have exceptional yield potential, plant bug controls may still be applied. Our greatest concern now in cotton is boll rot and disease. The past few days of overcast skies and rain showers have increased boll rot. The next weeks forecast is much the same. Other than a few southwestern counties, the state was spared from the excessive rainfall from Isaac.

At present, the insect action is primarily happening in soybeans and to a limited degree in peanuts. The lep feeders are occurring on soybeans state wide. We have more soybean loopers on beans in the Tennessee Valley area of North Alabama than I can ever remember. This complex also includes the green cloverworm statewide and the velvetbean caterpillar as far north as Selma and Montgomery in central Alabama.

Loopers, (all are the soybean looper, more difficult to control) are occurring at 1 to 8 or more per sweep. Most of our beans are drill so we cannot use a drop cloth. Our threshold experience with loopers using drop cloths is well established at 5-8 per row foot. We are wrestling with a sweep net threshold. Two loopers per sweep are not causing more than 5% foliage loss while 8 per sweep is causing 30-35% foliage loss. Our threshold is 20% foliage loss with beans at the stage they are now. So somewhere between 2 and 8 loopers per sweep is a treatable level. Based on my field observations I would treat in the neighborhood of four loopers per sweep.

Stink bugs are increasing in beans and will likely continue to do so in the days ahead. Therefore, in many fields a stink bug material (pyrethroid) or acephate (Orthene) may need to be added as we treat for loopers with the recommended insecticides of Tracer (Blackhawk), Intrepid, Steward or Belt.

One or more soybean fields in Southwest Alabama are infested with the garden fleahopper at damaging levels. This is a first for this insect on soybeans. They occurred on peanuts in that area a couple of weeks ago.

Some peanut fields are also infested with this mix of caterpillar pests. In this mix we are also finding fall armyworms, southern armyworms, corn earworms, cutworms, yellow striped armyworms and immature burrowing bugs.

Both soybeans and peanuts need to be scouted weekly for the remainder of this season and future seasons. The old method of spraying an insecticide on soybeans or peanuts when fungicides are applied is really just a stab in the dark. The odds of this being good timing for insect control is somewhere between slim and none. With the price of beans we have to do a better job with insect control than automatic sprays based on the stage of the beans.

Most of our comments in the next week or so will be directed towards soybeans and peanuts.

Soybean Loopers Threaten Alabama's Soybean Yields

Soybean loopers became an economic threat to soybean growers in Baldwin County (on the Gulf  Coast) this year during the first week of August. Soybean loopers were treated in many Blackbelt (west central Alabama) soybean fields this week as looper numbers increased and defoliation levels rose. Now farmers on both sides of the Tennessee River are preparing to spray numerous soybean fields for this pest for the first time since 1988. Densities of soybean loopers at the Fairhope Research station across the bay from Mobile were an average of 8 per sweep (all sizes) in test plots that were averaging an estimated 10 to 15% defoliation when an insecticide was applied on August 7. Eight days later defoliation in untreated plots ranged from 25 to 40%. Farmers in the Tennessee Valley have found as many as 3 loopers per sweep this week and defoliation levels are steadily heading toward the 20% threshold level in many fields.  Farmers in north Alabama west of I-65 are watching the weather hoping that they can find  an opportune time to spray the loopers during  a projected 5 day period of scattered showers. Most of the soybeans in the Tennessee Valley were planted behind wheat and yield potential is good presently. These later planted soybeans are mostly in the R4 to R5 stage of development and need another good rain to produce a strong yield.  One such field that is being monitored in Franklin county was running one looper per sweep on August 25 and had 5% defoliation. This field had 2 loopers per sweep (all sizes) on August 30 and 10% defoliation.  A few loopers had pupated in the field and had attached themselves with silk to the undersides of leaves. No diseased worms were observed while sampling. Stink bugs are also present in these fields but numbers are mostly below the threshold of 2 per 15 sweeps from bloom to mid-pod fill and 3 per 15 sweeps after mid-pod. Three-cornered alfalfa hopper (3-CAH) numbers are usually running from less than one to two per sweep .  Pod worm numbers are very low in most fields. Chemicals currently listed in the Extension Soybean IPM guide for soybean looper control are Belt 4SC, Intrepid 2F, Steward 1.25 SC and Tracer 4 SC. None of these products will control stink bugs or 3CAH’s. Belt, Steward and Tracer are labeled for control of pod worms in soybean. Hopefully, one application will be sufficient this year to manage soybean loopers but growers should continue to monitor fields following looper sprays to insure that populations do not rebound.

By: Tim Reed- Extension Entomologist and Ron Smith- Entomologist and Professor Emeritus

Monday, August 20, 2012

Update for the Week of August 19

Our April-planted cotton is beginning to open, and has varying levels of boll rot due to the weather the past 7-14 days. This same weather pattern of frequent thunderstorms and overcast conditions has been ideal for the spread of leaf spot diseases in out late planted cotton.

Insects have been light-to-nonexistent in recent days. There are a few plant bugs present and stink bug numbers have increased in some fields. I am not sure if either are at damaging levels, especially the plant bugs.
I believe we could safely say that leaf spot diseases are potentially more important than insects for the remainder of the season.
Growers who have peanuts or soybeans should monitor these crops carefully for the remainder of the season. Peanuts are attractive to a number of foliage feeding insects – including loopers, fall armyworms, bollworms, budworms, green cloverworms, velvet bean caterpillars and cutworms. Two peanut fields in Monroe County were identified last week with a high infestation of the garden fleahopper. To my knowledge this is the first time for this insect on peanuts. I am not sure what kind of damage potential they present. However, in cotton this pest can cause extensive foliage damage by leaving all leaves with stippling type feeling.
This same type of damage in peanuts would seem to be just as economic as a foliar disease.
Soybeans would be susceptible to damage from all the leps mentioned under peanuts plus the pod feeders – podworms and stink bugs. Many of our beans are late, planted behind wheat, and were just in full bloom the past 10 days. These beans will be susceptible to insect injury for weeks ahead. Only by scouting will growers know when economic insect losses are occurring and when controls are needed. We already have some fields in Baldwin County with damaging levels of soybean loopers. Foliage loss was as high as 35% last week when I made surveys in that area. Soybeans will be the last crop that stink bugs are attracted to this season. Even though it has been a light stink bug season, if they all accumulate in soybeans late season, controls will likely be needed.
I have heard little from the Kudzu bug on soybeans after finding them in the northeast counties of Cherokee and Cleburne back in July. Follow up surveys are needed in that area whenever time permits.
As the season winds down we will get back with further updates as new information becomes available and the situation changes.

Tuesday, August 14, 2012

Update for the Week of August 12

Last week was rather quiet insect wise on cotton. Many areas received thunderstorms throughout the past 7 days. The comments that I will make today are based on observations made in the field from several different areas of the state last week.

The first point is when to back off of stink bug controls. Our early April cotton is beyond the eighth or ninth week of bloom with few to no 10-12 day old bolls remaining. In fact, my test plots of PHY 375 planted April 9 had several open bolls per plant early last week. Even with cotton that still has a few 10-12 day old bolls remaining, stink bug numbers are so low in most fields that a stink bug threshold could never be reached. I would not be concerned at all with 10-20% internal damage as cotton is maturing out and beginning to open. For those who would be spraying with ground equipment, and that would consist of the majority of growers in Alabama, a ground rig going through mature cotton would destroy far more good bolls than the few smaller bolls near the top of the plant that stink bugs might injure.

Spider mites populations held steady last week but did not seem to increase, likely due to the frequent thunderstorm occurrence. I would just keep an eye on them and delay treatment decision as long as the current weather pattern holds.
One of the heaviest tobacco budworm flights seen in several years has been ongoing in the southern counties. Moths, eggs, and small larvae have occurred in high numbers from Dothan in the southeast to Fairhope in the southwest. This will have no impact on cotton with Bollgard or WideStrike technology. However, conventional varieties are a different story. I was in research plots of conventional cotton with no insect technology at Fairhope, AL on August 7 and found 32% worm square damage with 9% of the squares containing live larvae. Who says the technology has less value than it once did? In the old days, what would we do under this level of pressure, with thunderstorms occurring every afternoon?
Growers that may be impacted by this budworm pressure are soybean and peanut producers. If these crops are infested with budworms then the newer chemistry will be required because pyrethroids would not perform at all.
Chemical choices would be, in alphabetical order: Belt, Steward, or Tracer and possibly Lannate. Some might include Intrepid with this group but I do not know how effective it would be on budworms. Peanut growers should monitor their fields closely for the next 7 to 10 days for budworm numbers. New growers applying a fungicide to soybeans should not automatically add a pyrethroid for insurance purposes. If an insecticide is added in a preventative mode, I would suggest Dimilin at 2 oz. for future foliage feeders.
One other soybean pest that I will mention in closing is soybean loopers. Most soybean fields have a few green cloverworms or an occasional looper. However, one field in Baldwin County was observed last week with about 10 loopers per foot with about 10-15% foliage loss already. Therefore, all fields are not alike and must be scouted to stay on top of the soybean insects.

Monday, August 6, 2012

Corynespora Leaf Spot

In those areas that have gotten good rain or are irrigated, Corynespora leaf spot has become an issue in cotton.  Much of the cotton acreage in Baldwin Co, an area that has gotten good rain, has been treated at least once with either Twinline or Headline fungicides.  While Phytogen varieties, which previously were shown to be susceptible to Corynespora leaf spot, have been damage, this disease is also a threat to defoliate other cotton varieties as well.

While it’s getting late, producers and consultants should be advised to check cotton for symptoms of Corynespora leaf spot as they scout weekly for insect pests.  Labels for both Twinline and Headline specify that the first fungicide application may be made when first symptoms appear in the lower leaf canopy.  Dryland or irrigated cotton with a 2+ bale/A yield potential that’s getting good rain should be targeted for treatment with a fungicide.

In research trials at outlying units, noticeable disease development has been seen in fungicide trials in dryland cotton at the Gulf Coast Research and Extension Center and irrigated cotton at the Plant Breeding Unit.  At GCREC, heavier leaf spotting was noted in Phytogen 499 as compared with DPL 1050, which suffered only light disease development.   In the PBU study, noticeable leaf spotting with some (10%) defoliation was noted in Phytogen 499, while some spotting on the lowest leaves was found in DPL 1050.  Hard to tell in both trials whether or not the single application of Headline has had much impact on disease spread.  My intention is to evaluate disease development in cotton variety trials at both of those locations as well as Wiregrass Research and Extension Center sometime in the next week.   In the good looking dryland fungicide and variety trials at the Field Crops unit at EV Smith, disease development is minimal.  So, frequent showers or irrigation appears to be a critical trigger for disease development and spread.  If you want to look at trials at the outlying units, get an outline from the station superintendent.

I have also seen minor leaf spotting caused by Stemphylium and Alternaria fungi in cotton.  Leaf spotting attributed to these fungi are associated with a potash deficiency.   Individual leaf spot lesions are much smaller when compared with Corynespora leaf spot.  On Phytogen 499, the target or zonate pattern leaf spots associated with Cercospora leaf spot have a diameter of up to ¾ inches and are circular compared with the unevenly shaped, and much smaller Stemphylium or Alternaria leaf spots.

If you have any questions with the diagnosis of this disease, send a sample overnight fedex or UPS to the Plant Diagnostic Laboratory, S Donahue Dr., Auburn University, AL 36849.

By: Austin Hagan

Update for the Week of August 5

We are now in the home stretch, as far as insect control, in most fields of April planted cotton. Overall, there are a few things that I would be on the outlook for this week.

Stink bugs pose the greatest threat to most fields for the remainder of the season. Numbers vary greatly from field to field and in many cases from area to area within fields. For this reason, surveys must be thorough enough to detect the overall situation in each field. A dozen or so bolls will not accurately reflect the true infestation in most instances. Remember to select or sample 10-12 day old (quarter diameter) bolls. First separate out those with external damage from those with no external feeding signs. Second, crush those bolls with external damage and observe for internal injury. Our recommended “dynamic threshold” ranges from 30-50% internal damage early in the blooming period down to 10% during weeks 3-6 of bloom. This low threshold corresponds to the period when a high percentage of the total bolls are being set. Later into the blooming season, which is where many of our fields are now, we can relax our treatment threshold back up to the 30-50% range.

Now onto some other pests:

The mid-to-late July bollworm flight was maybe the lowest in modern times. Bollworms have been almost non-detectable in fields in central, SW and SE Alabama, even in cotton with no genetic technology.

As to tobacco budworms – while at the Wiregrass Research Center (SE Alabama) last week, numerous TBW moths were observed. This matches up with reports from SW Georgia that indicates an extremely high budworm flight going on in that nearby location. This will not be anything of concern for   Bt cotton but this could be a very significant event for peanut growers and even soybeans.

No questions were received concerning spider mite control last week. However, I personally observed mites in numerous fields that have not historically had mite infestations. They are present in many fields and their explosion will be greatly influenced by temperature and moisture for the remainder of the season. Growers treating for stink bugs would be wise to select an insecticide that is least likely to help flare mites.

With these thoughts we will end today and get back with another update as conditions change.

Soybean Insect Pest Update

Fall armyworms have been reported infesting pastures across Alabama and last week this pest was found feeding on soybeans in Lawrence County in the Town Creek area. These fall armyworms appeared to have moved from a bermudagrass pasture and crossed a wooded area to reach the soybeans. The caterpillars were feeding on the soybean foliage in the portion of the soybean field adjacent to the woods. Since this report from last week, fall armyworms and yellow striped armyworms have been found in many soybean fields in North Alabama at densities as high as 3 to 4 per 15 sweeps. Since theses armyworms have been found across the R2 to R6 soybeans, it is likely that these worms were derived from eggs deposited in the fields by moths. Only a very limited number of soybean fields have been treated strictly for foliage feeders in Alabama thus far---but numbers of green clover worms are increasing in north Alabama and velvetbean caterpillar numbers are increasing in south Alabama as far north as Monroe county. The economic threshold for foliage feeding caterpillars from pod set to maturity is as follows: Prevent greater than 20-percent leaf  loss. Treat prior to 20-percent leaf loss when five to eight foliage feeding caterpillars (soybean loopers, armyworms, green clover worms, velvetbean caterpillars)  0.25 inch long or longer, are present per foot of row.

Treat when you catch an average of 1.5 foliage feeding worms per sweep. Soybean loopers are harder to dislodge with a sweep net and each looper should be counted twice. Each larva eats a high percentage of the total amount of foliage it consumes during the last 4 to 5 days of the larval cycle. If disease is present in the population growers may wish to delay application  for 2 to 3 days, especially if larvae are less than a half inch long and populations are not much above the minimal threshold. Both fungal and viral disease can wipe out a caterpillar infestation within a week under the right conditions. Podworm and stink bug numbers have been below threshold levels thus far in the vast majority of soybean fields.  However soybeans planted behind wheat could see increasing populations of these two pests as we enter the pod-fill stage.  Three-cornered alfalfa hopper (3CAH) numbers are variable (usually less than 2 per sweep) but numbers in most untreated fields are increasing.  Some growers who applied a fungicide to their soybeans have also included an insecticide to reduce 3CAH numbers.  As soybeans mature we will see more fields with multiple insect pest species present.  At times there will be 2 or more species at densities which are just below treatment threshold levels. It can be difficult to make a treatment decision in this situation.  If you need assistance in making a soybean treatment decision you can call me at 256-627-3450.

By: Tim Reed

Monday, July 30, 2012

Update for the week of July 29th

The dominant question last week was concerning spider mite control. Several calls were received from consultants or agri fieldmen in the southern part of the state. Their question was not so much what to spray with (chemical choice) but instead when to spray. Most were scheduling stink bug sprays within a few days and wanted to know whether to add a miticide or not. Without seeing the fields, that is a difficult decision to make over the phone. My thoughts were that it could depend somewhat on how widespread the mites were in the field, the level of mite infestation and maybe most importantly – what is the weather outlook for the next 7-10 days.

Mite populations seem to hold steady in good rainfall patterns but explode during hot-dry weather. Even though we have had scattered thunderstorms for the past several weeks, there are many places where no rainfall has occurred. Last week was hot, mid 90’s or higher all week, so mites likely increased in number.

My suggestion would be to go ahead and treat mites if the weather outlook is for hot dry weather for the next 5-7 days. Most of our mites controls this season have been with abamectin (Agri Mek) at 8 oz/ac and results have been good.

Stink bug populations are still hanging around, in low numbers in many fields. However, from personal experience in a plant bug trial area in central Alabama that is located adjacent to corn, stink bug numbers have exploded in the past two weeks. Both brown and southern green species are well above the threshold level on the corn-cotton borders. Where cotton yields are promising and quarter diameter 10 day old bolls are still developing, stink bugs should be watched closely and controlled when above threshold. Cotton is at various stages now so our “dynamic threshold” would depend on where we are in the blooming-boll development cycle. Remember that 10% is our suggested threshold from weeks 3 through about 6 of bloom.

One other call was received last week concerning one or more fields in Baldwin County (Gulf Coast) infested with damaging levels of the garden fleahopper. We had several fields in recent seasons with this pest in the Mobile county area. The GFH seems to be primarily a foliage feeder but can damage every leaf in a field.

As of this date the bollworm/budworm complex is almost non-detectable, even in cotton with no caterpillar technology.

Tuesday, July 24, 2012

Update for the week of July 22nd

The past 7-10 days has been about as quiet insect wise as I ever remember for that time of the season.

Insect wise, we still have a few scattered Tarnished Plant Bug adults and a few immatures in some unsprayed fields – but I am not aware of a single field that has economic or treatable levels. In many instances where I have actually monitored fields, I found that part of the plant bug population is the clouded plant bug species. This species has been present in some fields in Alabama for most of the month of July.

Spider mites are still hanging around but have not exploded in recent weeks. The weather in the form of multiple thunderstorms appears to have slowed mites. Speaking of weather, some areas of the state have received multiple rain events of one to two inches or more while others have received only tenths a few times. Cotton ranges from as good as it has ever looked to knee high and blooming out the top depending on the planting date and the amount of rainfall received. In general, the earlier planted cotton that was stressed due to the heat and drought in May and June offers the least yield potential.

Back to insects now – a few stink bugs, mostly brown, are present in most fields. However, the numbers do not reflect the level we anticipated following a mild winter and the number seen on wheat at harvest time. It appears that the hot dry weather last month took its toll on stink bugs also. Boll damage to stink bugs is less than 10% in many fields. Cotton maturity ranges from the third week of bloom on late planted cotton to probably the sixth or seventh week of bloom on earlier planted fields.

Since we are at least at the third week of bloom, growers might want to consider a clean of spray for subthreshold levels of plant bugs and sink bugs in fields that have not received a foliar insecticide application yet in 2012.

This used to be the time we could also catch some escaped bollworms with this clean up spray. However, at this point, the bollworm flight statewide is very low and escaped worms are almost non detectable. Still the bug complex alone could help justify a clean up spray.

This is the way we see it on July 24, we will be back with an update as the season unfolds and conditions change.

Thursday, July 19, 2012

Corynespora Leaf Spot on Cotton

I collected Corynespora leaf spot on cotton at the Plant Breeding Unit.  The cotton, which is just beginning to flower, follows cotton and is irrigated.  Weather patterns for the past week have been favorable for the development of this disease.  Much of the state probably will get a good shower or two sometime in the next 7 days.   Irrigated cotton with a dense canopy that has gotten good rains over the last two weeks is at highest risk for disease.  Given rainfall patterns over the past two weeks, cotton in southwest and west Alabama may be at highest risk for disease.  See the PP-715 Leaf Spot Management in Cotton Timely Information for more information on control procedures and recommended fungicides.

Bob Kemeriat, the extension plant pathologist found this disease a week ago in a Georgia cotton field.

 By: Austin Hagan, Professor and Extension Plant Pathologist
Department of Entomology and Plant Pathology at Auburn University
149 ALFA Building
961 South Donahue Drive
Auburn, AL 36849
Phone: 334-844-5503
Cell: 334-321-8248
Fax: 334-844-4072

Monday, July 9, 2012

Insect and Weather Update for the week of July 9th 2012

The past 10 days have been characterized by heat, drought, scattered thunderstorms, aphids, and in some cases spider mite decisions. Some areas have received one or more rainfall events of 1 to 3 inches or more while others are still suffering extreme drought. Some of these storms have brought high winds, downed trees, demolished buildings and hail.

Insects have been rather quiet overall. Many field men have made aphid treatment decisions with significant acres treated. In at least one incidence, both aphids and mites were at treatment levels. Other more sporadic fields have needed adult tarnished plant bug controls. In the majority of cases the plant bug population has now shifted to immatures. In these cases field men need to switch from sweep nets to drop cloths to quantify these immature plant bugs. Two or three immatures per drop could be considered a threshold level requiring treatments, especially if “dirty” blooms are present. Pinhead square retention is no longer the best way to look for plant bug damage since they spend more time down in the canopy feeding on larger squares (which later become dirty blooms).

I have not had any calls yet, but field men in the southern areas of the state need to pay attention to stink bugs since our oldest fields are now at week three, four or more of bloom. Weeks three through six of bloom is when stink bugs are most damaging. A good threshold for treatment during this period is 10-15% internal damage to quarter diameter (still soft) 10-12 day old bolls. Look for brown areas near the seed  and warts on the inside boll wall where stink bugs have penetrated in search of a protection source in the form of developing seed. If the population of stink bugs is primarily the southern green species then we have choices of both pyrethroid and phosphates. However, as most likely the case, the population may be predominately brown stink bugs. Here we would need a phosphate such as Bidrin or either a high rate of bifenthrin and get decent suppression.

Reports were just received of an increase of small larvae on peanuts in south-central Alabama. My guess would be that they are tobacco budworms. By July 15, newly hatched larvae will more likely be corn earworms.

Tuesday, July 3, 2012

Pest Update

The dominant factor in cotton the past one to three weeks has been the drought and heat. The weather has impacted both the crop directly and management decisions for insects. Some localized areas received rainfall on July 1 or 2. However, most cotton remains under stress from lack of moisture.

Aphids are the insect of primary concern since populations have built in many fields, putting additional stress on plants. Most growers delayed treatment decisions for aphids until this week – waiting for either rainfall or natural diseases. However, many are wisely spraying for aphids this week.

In some fields plant bugs are also present. Adults have diminished statewide but immatures have begun to emerge in many fields. I have also noted the presence of fleahoppers (both adults and nymphs) and clouded plant bugs in the mix. Field men have reported a large increase of bollworm moths in southwest Alabama fields this week.
Another significant even in row crop insects occurred during the past week. Kudzu bugs were observed feeding on soybeans in numerous fields in Cherokee County and in other fields in north Cleburne County and near Collinsville in Dekalb County. This pest has the potential to dramatically impact soybean production in Alabama as it already has in Georgia, South Carolina and North Carolina. First of all, soybeans will need to now be “scouted” as cotton has been since the late 1950’s. Mid-season (July) sprays will likely be required which will open the door for greater problems with podworms. Additional later sprays for the Kudzu bug will also be necessary. We will talk later about scouting techniques, thresholds and the selection on appropriate chemistry.

Monday, June 25, 2012

Weather Conditions and Pest Control

First we will give an overview of weather conditions, especially since this may be impacting some of our insect and pest control decisions in the coming days. After a good moisture and rainfall pattern of about 10-14 days ago, our crops have reached a hot-drought stressed condition at present. The situation is worse in the northern area of the state where less rainfall fell during the last thunderstorm period. I saw corn wilted bad in the Tennessee Valley on Tuesday (June 19).

This droughty situation could well impact spray decisions with pests such as aphids and s. mites in the immediate days ahead. Aphids are building state wide and drought stress plants are where I am more suggestive for chemical controls instead of waiting for the natural fungus.

Tarnished Plant Bug adults are also being reported from some fields from the Tennessee line in the north to the Florida line in the south. Square retention is dropping, especially in fields in South Alabama that are a couple of weeks into bloom – these would be early-mid April planted cotton. Also in these some fields, adult brown stink bugs are being reported. We know from past years what stink bugs do to small thumb sized bolls when no larger ones are present.
If present in cotton, stink bugs will feed on small bolls to develop. Knowing this impacts the chemical that we may want to choose for TPB control. It needs to be a product that also controls or highly suppresses Brown Stink Bugs. The best options here would be Bidrin or a high rate of bifenthrin. Aphids in the picture would further complicate the chemical selected. Of the neonic type products, Centric might be the best choice for Tarnished Plant Bug adults, Brown Stink Bugs and aphids.
Three-Cornered Alfalfa Hopper damage is still evident in cotton, in reddish stunted plants that have a girdled and swollen area around the main stem. However, this damage is old now and most plants are too tough for main stem girdling by the Three-Cornered Alfalfa Hopper.
The biggest insect news of the week in Alabama was the finding of the Kudzu bug in soybeans in Cherokee County, Alabama on June 21. The Kudzu bug had been found in about 25 counties on Kudzu but this was the first find on soybeans. Alabama growers will want to lean heavily on recent research conducted in Georgia, South Carolina, and North Carolina on this new envasive pest. We need to beef up our scouting on soybeans for this pest – especially the immature stage.

Friday, June 22, 2012

Kudzu Bug Found Infesting Alabama Soybeans

The kudzu bug was detected this week in 2 soybean fields in Cherokee county which borders on Georgia where the pest was first detected in the Athens/Atlanta area in 2009. The pest has spread rapidly since it was first detected and now has been found in 7 SE states. The kudzu bug had been found previously on kudzu in 25 Alabama counties but this is the first report on soybeans. Economic yield losses by soybeans due to kudzu bug feeding have been reported in Georgia. (The following information was taken from the 2012 Georgia Soybean Production Guide)  Adult kudzu bugs are oval shaped,  about ¼ inch in diameter, and greenish brown in color. Eggs are laid in double-rowed batches of 35-50 eggs and are white in color. Nymphs are also oval shaped and are light green to brown in color and have numerous setae/hairs. Both adults and nymphs are most commonly seen on plant stems using their sucking mouthparts  to feed on plant sap. The effects of kudzu bug feeding on soybeans is similar to drought. Excessive feeding weakens and stresses the plant which can result in fewer pods per plant, fewer seeds per pod, and reduced  seed size.  Overwintering adults survive under pine bark and ground debris . Key reproductive hosts of kudzu bug include kudzu, wisteria , clover and soybeans. Adults begin laying eggs on kudzu shoots in  mid-April and continue laying eggs on kudzu for several weeks. Time required to reach the adult stage is about 6-8 weeks. These new adults then disperse to soybeans and other reproductive hosts beginning in mid-June and continuing thru mid-July. Soybeans become attractive to kudzu bug adults when plants are 8-10 inches tall. Early planted soybeans appear to be at greater risk for kudzu bug infestation compared with later planted soybeans. Adults will begin laying eggs on the underside of soybean leaves and a generation requiring about 6 weeks will be completed on soybeans. Initial field invasions tend to be more concentrated on field margins but will eventually spread throughout the field. In many situations we will begin to see immature kudzu bugs in soybeans at about the R2-R3 stage. Kudzu bugs can be scouted using a 15-inch diameter sweep net. Kudzu bug populations can be extremely high. Georgia entomologists are suggesting a threshold of one immature kudzu bug per sweep. This suggested threshold is based on 2011 field trials where a single properly timed insecticide application preserved soybean yield. If insecticides are applied when adults are still actively migrating from kudzu to soybeans (late June and early-mid July); additional applications may be needed. Research is ongoing to verify and refine management and treatment thresholds for kudzu bugs in soybean. Multiple classes of insecticides have shown activity on kudzu bugs. Insecticide treatments containing bifenthrin, cyhalothrin, zeta-cypermethrin, carbaryl, or acephate provided greater than 80 percent control 2-5 days after treatment.

Thursday, June 14, 2012

Current Insects in Cotton at Economic Levels

Today I would like to discuss three insects that are occurring in cotton at economic levels in certain fields. Two of these insects are actually impacting other crops, particularly soybeans and peanuts, as well.

Adult tarnished plant bugs (TPB’s) are being reported at moderate to high levels in some fields statewide. More findings are reported each day and there are likely many fields where they are present but have not been observed yet. At this point, no one has reported high pinhead square loss. This square loss is what we like to base our treatment decisions on. However, based on past experiences, once the adult TPB’s are present it is just a matter of time until some level of square loss is detected. These are all migratory adults that have moved into cotton from wild hosts. They will feed on pinhead squares, which cause abortion, and also deposit eggs in the plant stems. These eggs will hatch in two plus weeks into an immature field generation. The longer the period that adults are allowed to roam in fields, the longer the period of hatching immatures will be in coming weeks. Knowing this, growers can make their own decision as to when controls should be applied.
The second insect I will mention is the tobacco budworm (TBW). An extended flight of budworms has been ongoing in various areas for about two weeks already. This is of no significance to 98% of the states acreage that is planted to Bollgard II or WideStrike varieties. However, this makes a tricky situation in conventional cotton that may need plant bug sprays during this TBW period. This TBW flight is also impacting later planted peanuts that have a limited amount of vegetative growth. Budworm moths seem to be attracted to peanuts with a vegetative width of 3-4 inches. Earlier peanuts that have six of more inch vegetative width do not appear to have as many budworms present. We collected about 250 quarter inch budworms yesterday at Headland, Alabama on about 600 row feet. This was not what I would consider an economic or treatable level. However, up to four budworms per row foot have been reported in some fields and controls, with the newer chemistry, have been applied.
The third insect that is causing widespread concern in cotton at present is the three-cornered alfalfa hopper (3CAH). Numerous fields in the Tennessee Valley area of northern Alabama have had damaging levels of 3CAH reported. This problem has extended as far south as Talladega County. Treatments have been applied. Soybeans are also experiencing a problem with this insect, even more so than cotton, and over a much larger geographical area. 3CAH damage is caused by the girdling of the main stem of both cotton and soybeans by both the adult and immature 3CAH. No good thresholds exist from Alabama research. Usually this problem and damage is greater on field borders but consultants have reported damage field wide in both cotton and soybeans. Treatment thresholds are difficult to develop for 3CAH, just as they are for grasshoppers. Treatments sometimes have to be made based on the risk that certain species present, and not the level of damage observed. Sweep nets are very effective in documenting the number of 3CAH per row foot.

3-Cornered Alfalfa Hoppers Attacking Seedling Soybeans

Three-cornered alfalfa hoppers (3CAH’s) have been found in large numbers in north Alabama soybeans this year and some fields have already been sprayed twice. Numbers of 3CAH’s are comparable to the relatively high numbers observed in 2010. 3CAH girdling of seedling soybeans can result in plants falling over later when strong winds occur. Often plants that have been girdled and do not lodge produce normal yields. The current treatment threshold for soybeans less than 10 inches tall in Alabama is to treat when pests or damage is noted and stands are threatened. The Mississippi seedling soybean treatment recommendation for 3CAH is to apply insecticide from plant emergence to 10 inches in height when the plant stand is reduced below the recommended plant populations. Georgia’s soybean IPM guide recommends treating soybeans up to 12 inches tall when 10% of plants are infested with nymphs and/or adult 3CAH’s. The most common method for sampling soybeans for 3CAH is the sweepnet.  There is no research based threshold for seedling soybeans which states the number of 3CAH’s per sweep for a given row spacing that is needed to trigger an insecticide application. Reports indicate numbers of 3CAH’s per sweep are presently higher in drilled soybeans than in soybeans planted using a 30 inch or greater row spacing.  Soybean insecticide seed treatments to date have provided good control of 3CAH’s for approximately 3 to 4 weeks after planting but with the heavy pressure we are currently seeing even fields that have been planted with insecticide-treated seed should be monitored for damage. 3CAH damage tends to be greater in soybeans planted behind wheat than in full-season soybeans. Seedling soybeans sprayed with an insecticide frequently see 3CAH populations rebound within 2 weeks and another insecticide application may be required.

By: Tim Reed, Extension Entomologist, Auburn University

Thursday, June 7, 2012

Tobacco Budworms in Early Season

A tobacco budworm moth flight this week resulted in eggs being deposited in cotton terminals as far north as Prattville, Alabama. On June 5th, about 40 budworms were collected from 100 tobacco plants at Prattville. All plants had feeding signs but parasites and predators were working on the population. Budworm feeding was also noted on tobacco planted as a sentinel crop at Headland, Alabama yesterday (June 7th).

A call was received a few minutes ago about what is believed to be budworm larvae on peanuts from the Covington County Alabama-Florida panhandle area. These peanuts were young and had a limited amount of foliage with up to four budworm larvae (3-7 days old) per row foot. This same situation occurred about 3-4 years ago where budworms defoliated some fields of peanuts in June. At this early stage of the season, controls may be necessary due to the limited amount of vegetative growth of the peanuts.

Monday, June 4, 2012

Tarnished Plant Bugs Found

A significant level of adult tarnished plant bugs was found this morning (June 4th) in nine true leaf cotton in Autauga County Alabama. Levels of up to five adults per 100 plants were reported. No pin head square loss was observed but it is likely just a matter of time until damage is observed. Controls are planned.

In addition to these tarnished plant bugs, eggs, most likely tobacco budworms, were also reported.

Friday, June 1, 2012

Announcing Alabama Scouting Schools

Announcement: Alabama Cotton Scouting Shortcourses Meeting Sites and Dates
  • June 12th (Tuesday) 2012; Autaugaville, Alabama- County Agricultural Center
  • June 13th (Wednesday) 2012; Headland, Alabama- Wiregrass Research Center
  • June 19th (Tuesday) 2012; Belle Mina, Alabama- Tennessee Valley Research Center
All meetings begin at 8:30 AM
Contact Person: Dr. Tim Reed (256-627-3450) or Dr. Ron Smith (334-332-9501)

Note: Dr. Austin Hagan will discuss cotton diseases at the Autaugaville and Headland sites. Dr. Tim Reed will cover soybean insects at all three sites.

Following are thirteen questions that represent the type of information that will be discussed.
1.      Why are grasshoppers easier to control in March/early April than May?

2.      If a foliar is needed for thrips suppression, when is the ideal stage of cotton to apply it?

3.      If you see damage to cotyledon stage cotton (no till) planted behind corn residue, what is the most likely culprit: snails, slugs, or pill bugs?

4.      What is the best method to determine when plant bug controls are needed in pre-bloom cotton?

5.      How would you measure the number of tarnished plant bugs in post bloom cotton?

6.      You are at week four or five of bloom, what would be the threshold for stink bugs?

7.      Under what conditions (situation) would a phosphate insecticide give better control of stink bugs than a pyrethroid?

8.      What new thrips insecticide entered the market this season and does not flare aphids or spider mites?

9.      Suppose you find high numbers of fall armyworms feeding on grass in your cotton field border- should you prepare to spray the cotton?

10.   How old does a green boll need to be to be safe from stink bug damage?

11.   Under what conditions would aphids be more of an economic pest or problem?

12.   At what stage is cotton normally beyond thrips injury?

13.   How long should you wait to evaluate control behind a stink bug spray?

Wednesday, May 30, 2012

Thrips, Grasshoppers and Slugs

I’d like to mention several pests today, these being thrips, grasshoppers, and slugs.

1. Thrips- The heaviest pressure encountered this season was from about May 1-20. From monitoring 5 thrips trials, it appeared to me that thrips were later than normal moving from wild hosts and wheat to cotton. In addition, thrips pressure was not uniformly heavy. In some fields it seemed only low to moderate pressure was encountered. Cotton is growing very rapidly now and once it reaches the fourth leaf stage should be safe from economic thrips injury. Cotton planted on or about May 15th, with seed treatments, should not need a foliar overspray. Remember that seed treatments give adequate protection under most conditions until about 21 days after plant.
2. Grasshoppers- We lost another 45 ac. field in Talladega County to grasshoppers last week. The cotton was in the “crook” stage of emergence when attacked by grasshoppers. The strange thing about grasshopper feeding is that you can never predict when they will turn to cotton to feed. Grasshopper numbers do not mean much as far as thresholds. Sometimes a low number will cause a lot of damage and other times high numbers will result in no feeding. The usual damage from grasshoppers to cotton is in the form of stem feeding. They will feed on and cut the stem of the plant anytime from the crook stage up to about the 2-3 true leaf stage. Most grasshoppers in the system now are adults and are rather difficult to control. A max labeled rate of a pyrethroid or .75-1.0 lb. acephate is the usual grower choice in May. Back in March and April, a low rate of most any cotton insecticide will do a good job when the grasshoppers are still immatures.
3. Slugs- We have had two more locations last week where slugs were damaging stands of cotton or soybeans. This brings a total of five or more locations with loss of stands to slugs this season. These fields are always in no-till, high crop residue situations. Usually the grower/consultant looks in day time and sees pillbugs or snails and not slugs- only when observing at night do we find the real culprit, slugs. They bury deep in the residue during the day and only feed at night. Snails and pillbugs normally do not feed on cotton or soybeans. There is not much a grower can do about slugs. Metaldehyde at 10-40#/ac. is the only recommended chemical. At $2.25/lb. this would cost $25-85/ac. and controls, even then, may not be 100%. Seems to me that replanting would be the best alternative to slug damaged stands. Slug damage seems to usually be when cotton or soybeans are following corn.

Tuesday, May 29, 2012

Be prepared to scout corn for stinkbugs during the early ear formation stage!

We are fast approaching the early ear formation stage with our earliest planted corn. This is the time when stinkbugs do the most significant damage to corn. Early ear formation occurs about 10-12 days before silking, and is the stage when the ear shoot is less than ¾ inch long. In fact, you will not see the tiny ear shoot on the plant unless you pull back the leaf sheaf. Stinkbug damage at this time will result in ears being aborted or severely deformed. The deformed ears are C-shaped and are often called banana ears or cow horn ears. Note stinkbug damaged ears below. The direction of the curve is the side of the ear in which the damage occurred. Growers with corn fields located close to wheat fields or any small grains should especially be prepared to scout, as stinkbugs will migrate from maturing small grains into green corn. Also, fields located close to pine plantations often experience severe stinkbug damage as stinkbugs will over-winter under the bark of pine trees. We typically see more stinkbug damage in south Alabama and the Florida panhandle than north Alabama, but I would still encourage growers in north Alabama to scout their corn for stinkbugs. Pyrethroids work well on the green species while an organophosphate material, such methyl parathion, works best on the brown species. Auburn University recommends treatment when 5 percent of the plants have stinkbugs during the early ear formation stage. Be still when scouting, as stinkbugs will often try to hide behind the stalk.

By: Rob Duffield, Area Agronomist, Pioneer "Walking Your Fields Newsletter"
May 7, 2012

Thursday, May 17, 2012

Abundant Numbers of Thrips in Seedling Cotton Requiring Foliar Applications Across North Alabama

Many cotton acres in north Alabama are being treated for thrips as large numbers move from grass to cotton plants in the first to second true leaf stage. Thrips collected from a cotton field in Lawrence county on May 15 were mainly Tobacco thrips ( Frankliniella fusca) and Flower thrips (Frankliniella tritici) (usually called Eastern flower thrips). Soybean thrips (Neohydatothrips variabolis) and Western flower thrips (Frankliniella occidentalis) were also present but in much lower numbers. However, the proportion of each species in other fields could be different. Pyrethroids and organophosphates are the primary classes of chemistry being applied this week for thrips control in cotton. Spider mites are present in many fields and the foliar applications of these two types of chemicals for thrips may flare spider mites and farmers and consultants should monitor fields closely. Foliar chemicals for thrips are frequently being applied in a tank mix with a herbicide and growers/consultants should read the herbicide label carefully to insure that the insecticide and herbicide can be tank mixed. Adverse interactions between some tank mixed insecticides and herbicides can result in crop injury.

Written By Tim Reed and Barry Freeman, Extension Entomologists.

Monday, May 14, 2012

Thrips Damge in Cotton

Thrips pressure is quite variable based on the location and field. The two most significant factors affecting thrips damage seem to be planting date and rainfall. Thrips trials at Prattville, AL, planted on April 16, are showing low to moderate thrips injury even without a foliar application on top of seed treatments at planting. Trials planted a week earlier, April 9, are showing heavy thrips injury behind all seed treatments. Rainfall occurred on all trials during 5 of the first 10 days of May.

Most April-planted cotton should be out of the thrips damage window within 10 days or less. Cotton planted in April had three true leaves or more with the fourth or fifth emerging on May 11.

Growers planting behind the rainfall that occurred between May 7 and May 11 will likely not have to be concerned about making a foliar spray for thrips at the first true leaf stage. Seed treatments alone should provide adequate thrips control.

Cotton up and growing should be beyond grasshopper damage. The concern about pill bug damage in the one field in Talladega County this week turns out to be primarily damage from slugs and not pill bugs.

Monday, May 7, 2012

Grasshoppers and Pill Bugs in Cotton

The most common concern in cotton insects continues to be grasshoppers. The most significant change in the past 2-3 weeks is the fact that a percent of the population now are adult grasshoppers. Adults are much more difficult to control so current recommendations call for higher rates of whatever insecticide chosen. Several consultants are now applying one of the least expensive pyrethroids at higher labeled rates. Even then, a small percent of the adult population will escape controls.

Growers should be reminded that cotton planted in April with seed treatments will profit from foliar insecticides at the 1st true leaf stage. This is especially true in conventional tillage dry land situations.

A rare question was received today about controlling pill bugs in cotton. This situation usually occurs when cotton is planted in reduced to no-tillage behind corn. Pill bugs seem to only occur in high residue, high organic matter conditions. Little research or experience is available to base a pill bug recommendation on. After several phone calls, the best chemical options seem to be: Bidrin at 0.25-0.33; Orthene at 0.5; or Sevin at 0.5-0.75 lbs per acre. This is a question that will likely occur again on an infrequent basis. Dry weather and high temperatures should help solve this infestation. However, the next 48-72 hours may not present this situation.

Tuesday, April 24, 2012

Burrower Bugs Found in Alabama

Several reports have been received in recent days concerning the white margined burrower bug in seedling cotton. These observations have come from Geneva County in the south to as far north as Shelby county (near Birmingham). So far, no damage has been connected to this insect. Grasshoppers are also present in most fields and the stand losses have come from grasshoppers. The burrower bug has sucking mouth parts and does not chew into the stem as grasshoppers do with chewing mouth parts. The burrower bug is usually not an economic pest on either cotton or soybeans. Therefore, a dedicated spray for this insect should not be necessary. Seed treatments (Cruiser, Gaucho) do a good job of controlling burrower bugs once they feed on the seedling plants. Most all insecticides used for thrips or grasshoppers should also control these bugs. Immature burrower bugs are red, or red with black markings on their bodies. A certain stage of this bug requires the weed “henbit” as a food source. They move to cultivated crops once the henbit has been burned down prior to planting. This species is not the same one that attacks peanuts later in the season.

Friday, April 13, 2012

Immature Grasshoppers in Winter Cover Wheat

Cotton planting is underway in a significant way in some south Alabama counties. A question was received today from that area about what to do with the grasshoppers in winter cover wheat that is currently being burned down prior to planting cotton. Immature grasshoppers are present at thousands per acre in the wheat. My recommendation would be to control these grasshoppers at the same time wheat is being burned down or prior to the time the cotton begins to emerge. They pose a significant risk to stands if allowed to remain in fields. Based on our research of several years ago, immature grasshoppers can be easily controlled with a low-to-mid range rate of most any insecticide labeled for cotton. The pyrethroids do an excellent job and are very economical. Adding 1 oz. of Dimilin per acre to the mix would provide residual control of immatures for weeks down the road. Since we are still early in the spring, there could be some additional migration into fields from hedgerows and field borders. The problem with waiting until later to make an application is eventually these immature grasshoppers will become adults, which is much more difficult to control.

Wednesday, April 4, 2012

True Armyworms Spotted in Early April

True Armyworms were reported on April 2nd feeding on rye near the Wiregrass Research Station (near the Headland, AL airport), in Henry County. This insect had previously been reported from the Coastal Bend of Texas to South Georgia and as far north as Kentucky. The larvae feed mostly at night and may not be found in daylight hours until digging into the soil surface debris. The larvae vary from green to brown with lighter stripes on their sides and back. In some ways they look similar to Fall armyworms.

These caterpillars can cause extensive damage below the crop canopy before they are detected. Controls are suggested when 4 to 5 larvae per square foot are found and feeding is heavy on the lower leaves. It is important to protect the flag leaf.

Most all insecticides labeled for small grains will provide adequate control. They are not as hard to kill as fall armyworms in cotton. However, good coverage is important, especially when making applications by air.

Friday, January 27, 2012

Fine Tuning Cotton Insect Management for 2012

I. Thrips Control
  1. Need for foliar overspray
    • Influenced by planting date primarily but also to lesser degree by night temperature and overall growing conditions
    • Seed treatments planted from early April to about May 10th would benefit from foliar overspray
    • Seed treatments give 21 day thrips suppression as opposed to 28+ days with in-furrow granules
    • What you see with thrips injury above ground is reflective also of underground root conditions and growth
  2. Timing of overspray
    • Most beneficial when most of plants have 1st true leaf about the size of a small finger nail
    • Cotton with 4 or more true leaves usually does not benefit from overspray
  3. Multi state research in 2011 indicated that acephate (Orthene or generics) was equal to or superior to all other choices
    • Certain pyrethroids were a weak choice
    • Bidrin is effective but I would suggest saving for stink bug control. New label limits total use of Bidrin in one season to 1.2 lbs active.
      • New products tested: Benevia (Dupont) and Radiant ( Dow). Both looked very effective but not certain about registration date and cost.
II. Nematode Management

  1. Rotation- peanuts, grain sorghum, corn
  2. Variety selection- PHY367WRF has root knot tolerance
  3. In-furrow granules
    • Loss of Temik
    • Meymik registered on December 22, 2011 (production and supply for 2012 uncertain)
  4. Seed treatments
    • Suggest to use on lower risk fields
    • In high nematode risk fields would be like using a Band-Aid when a tourniquet is needed
  5. Fumigate (Telone)
    • Consider site specific nematicide placement (Precision Ag)
    • Nematodes usually not evenly distributed across field
  6. Deep tillage- grew cotton over 100 years without nematodes being a limiting factor- only since reduced tillage have they become a major problem
III. Plant Bugs

  1. Movement from wild host into cotton influenced by climate
    • Hot/dry results in high peak but short in time
    • Wet/cool spring results in low movement over longer period
  2. Most effective insecticides
    • Acephate (Orthene, generics)- can flare spider mites
    • Bidrin- good but only labeled for post bloom period
    • Centric- effective but hard on beneficials and fire ants
    • Pyrethroids- can flare spider mites
    • Diamond- very effective on immature stage post bloom, especially when tank mixed with one of the above
    • Intruder, Carbine, imidacloprid (Trimax), Belay, Vydate- less effective than others with one application
IV. Plant Bugs + Aphids (July)

  1. Intruder, Carbine, imidacloprid (Trimax, etc.), Centric
  2. Diamond may be combined with the above
V. Mid Season Worm Overspray

  1. May be more important with Phytogen varieties
  2. Timing could be mid July to early August depending on your north to south location
  3. Pyrethroids are a good fit here
  4. If brown stink bugs are also present, may want to select bifenthrin or Bidrin XPII (combination of Bidrin + Bifenthrin) or use highest labeled rate of other pyrethroids
  5. Role of Fire Ants in Cotton
    • Are the dominant beneficial in Alabama cotton today
    • Not only important in conventional systems but also reduces escapes in Bollgard and WideStrike (Example: Mississippi consultants spray BGII on % egg lay)
    • Some chemicals suppress fire ants more than others (Centric, Steward, pyrethroids, imidacloprid)
    • Dr. Tim Reed and I conducted a project at Prattville last season (Poster Presentation)
    • Results show less boll damage on both conventional and genetic cotton with fire ants in system as opposed to no fire ants
      • Numbers on the side represent the number of worm damaged bolls per 45 feet.
      Impact of Fire Ants On Bollworm
      Damage in Alabama Cotton
VI. Fall Armyworms

  1. 2010 and 2011 seasons have produced widespread outbreaks of the “grass” or “rice” strain of the FAW
  2. This strain primarily attacks pastures, hay, grasses and peanuts and are easy to control with most insecticides, including pyrethroids
  3. They do not prefer to feed on cotton or corn
VII. Stink Bugs

  1. Some level of scouting needed for most economical control
    • May need 0-4 sprays ($6-9 each considering application)
    • Could pay for a field scout with savings or reduced damage from stink bugs alone
  2. Most effective scouting is to examine 10-12 day old bolls for internal injury
  3. Use “dynamic” or sliding threshold which considers the number of bolls at risk at a given week of bloom
  4. Possible Reasons for Low Stink Bug Pressure in 2011
    • Winter temperatures (colder than recent winters)
      • Southern green stink bug is very sensitive to cold weather
    • Impact of hot, dry spring on wild host/corn—may have reduced numbers of brown stink bug species
  5.  New Stink Bugs
    • Brown Marmorated Stink Bug
    • Kudzu Bug (soybeans)
    • Red-Banded Stink Bug (soybeans)  

Brown Marmorated Stink Bug

Red Banded Stink Bug
Kudzu Bug

VIII. New Products and Technology

  1. Sulfoxaflor (Transform)- Dow
    • Effective on plant bugs and aphids
  2. Beseige (combination of Karate + Coragen)
    • Effective on broad spectrum of caterpillars (loopers, fall armyworms), plus would have green stink bug activity
  3. Endigo (combination of Karate + Centric)
    • Effective on certain caterpillars, plant bugs, aphids and green stink bugs
  4. Belay- in market place for past two seasons for plant bug/stink bug control
    • Still need more University research to get a good handle on effectiveness
  5. Prevathon (Dupont)
    • One of most active caterpillar insecticides ever developed
    • Excellent residual, depending on rate
    • Very rainfast
    • Should be targeted at egg stage or small larvae
  6. Bayer Twin-Link
    • Contains multiple Bt genes
    • Performs somewhere between WideStrike and Bollgard II for caterpillar control
  7. Bollgard III
    • Under development
    • Third gene is not a Bt so it has multiple modes of action for worms
    • Reduces escapes over Bollgard II and will provide long term resistance management for the genetic technology
  8. Poncho/Votivo Seed Treatment
    • Insecticide + biological nematicide
    • Looked at it in one trial on cotton and could see growth response and earliness, even under low nematode pressure

Friday, January 20, 2012

Overview of 2011 Cotton Insect Season

Early Season Pests
Thrips were extremely heavy from about April 15 to May 20. A major contributor to this heavy migration of thrips from wild hosts and wheat into cotton was the extreme drought conditions and absence of rainfall events during this period.

Plant Bugs
One peak movement of adult TPB into cotton occurred between June 20 and July 1. The majority of this infestation only happened in the earlier planted fields (most mature cotton). One insecticide application was targeted to these adult TPB’s when they were detected. Few immatures were detected in these fields in the coming weeks, so no in-field generation occurred. This may have been influenced by the extreme temperatures that occurred during this period (98-102⁰F).

Subeconomic numbers of bollworms occurred over an extended period from about July 15 to August 10. Few fields ever reached treatment threshold. 2011 was like the lowest bollworm pressure year on record. End-of-season damage boll counts on untreated genetic cotton were less than one boll per 10 feet.

Tobacco Budworm
Budworm numbers were non-detectable to extremely light all season long. Budworm larvae were too low to detect on conventional cotton and even on attractive crops such as tobacco when used as a sentinel crop.

Aphid numbers were very slow to build in 2011 but also slow to crash due to naturally occurring diseases. The fungal disease was slow to develop which left aphids in the system much later than normal. Aphids normally peak and crash prior to, or at, the early boll set stage but this did not happen in 2011. Also, observations indicated a resurgence of aphids in the mid canopy area of the plants in late season as opposed to the terminal area.

Stink Bugs
Stink bugs in 2011 were fewest in number and damage of any year since the boll weevil was eradicated. This was likely due to the colder than normal winter temperature effect on the southern green species and the extreme spring heat and drought effect on the brown species. The majority of the few stink bugs observed in 2011 was the brown species.

Fall Armyworms
The “rice or grass” strain of the fall armyworm was abundant over much of the season in pastures, hay, and grasses. This strain will feed on peanuts but not on corn or cotton. They are easy to control on pastures with pyrethroids and numerous other labeled agricultural insecticides.

Impact of Alabama Cotton Commission Research Support for Cotton Insect Management-30 Year Overview 1986-2011

Thirty years of cotton insect research in Alabama— from boll weevils to boll weevil eradication– to beet armyworms and pyrethroid resistant tobacco budworms– to genetically altered varieties– to boll feeding bugs (stink bugs). On the chemical arsenal side– from Azodrin, EPN + methyl parathion, Lannate, Bolstar, Curacron, Galecron, and Fundal and the original pyrethroids (Ambush, Pounce, and Pydrin) to generics of the third generation pyrethroids.
What an evolution and what a ride. Thanks to support by the Alabama Cotton Commission, we have survived and are better for it.

One could argue that the past 30 years have been the “worst of times and the best of times” in cotton insect control. I consider it to be the most exciting and revolutionary period in cotton insect control history. The worst of times was the period of 1987 to 1995 with uncontrollable beet armyworm outbreaks and the development of pyrethroid resistance to the tobacco budworm. The best of times was made possible by the eradication of the boll weevil and the introduction of genetically altered cotton varieties. The “best of the best” times were experienced by many growers in 2011, with one of the statewide highest yielding years in history, the best market prices in my career and the lowest insect loss year in history. Both Alabama and the U.S. reported total losses to insects in 2011 as 2-3%, the lowest ever recorded.
Two of the most important events in cotton insect control in the past 100 years happened during the past 30 years: boll weevil eradication and the introduction of genetically altered varieties. In 1996, the first year of Bollgard cotton, Alabama lead the cotton belt by planting 77% of our acreage to the new technology. I feel certain that this set a record in the adoption of new technology. This was the result of two factors, one much more significant than the other. The overriding factor was the pressure and damage by the tobacco budworm in 1994 and 1995. A secondary factor was impacted by funding by the ACC which allowed us to work with the Bt technology for four years before it was introduced. We felt very comfortable in recommended Bollgard varieties to growers based on four years of research experience.
Looking back at this 30 year period, we can see where research support by the ACC was involved at every turn and event during this historical period.
Let us look back now at some of the major insect events and advancements that happened during the past 30 years and discuss briefly how ACC projects gave answers to the most significant concerns and questions during this era. I will attempt to present these in chronological order.

A. Beet Armyworm Outbreaks
  • No effective chemistry available
  • Parasites and predators, if present, gave effective control-- but not possible during active eradication
  • Experimental insecticide, Pirate, highly effective but not approved by the EPA for emergency use until too late (August 1995)
  • The original efficacy work on BAW control with Pirate was done at Prattville Experimental Field with ACC support
  • Meeting with EPA in Senator Heflin’s office- Washington D.C.
B. Pyrethroid Resistant Tobacco Budworms
  •  Pyrethroid Resistant Tobacco Budworms
  • No effective chemistry available
  • 1994-1995 highest numbers in history, up to 5 larvae per plant
  • Yield losses astronomical
  • ACC funded research showed that a combination of Lannate + Larvin on 5-7 day schedule gave suppression

C. Transition from In-furrow to Seed Treatments for Thrips Control
  • Grower adoption rapid due to convenience and safety
  • Initially Cruiser and Gaucho
  • Transition to complete-pak with nematode suppression, Avicta and Aeris
  • ACC research showed that seed treatments were not as consistent as in-furrow, and often needed a supplemental foliar spray, especially if planting in the early season window. Also, that seed treatments were less effective than Temik for nematode and spider mite suppression
D. Introduction of New Caterpillar Chemistry
  • First- Tracer (Spinosad)- soft on beneficials, great on Tobacco Budworm
  • Later- Steward (indoxacarb), Prevathon (rynaxypyr)- long residual and rain fastness, Belt (flubendiamide)
  • All much more effective on small worms and require good coverage (ground application superior to air)
E. Evolution of Genetically Altered Technology
  • Bollgard
    • Single gene
    • Weak concentration of Bt in blooming zone of plant leading to mid season bollworm escapes under bloom tag
    • Benefits of pyrethroids overspray in mid-late July for sub threshold level of multiple pests
  • WideStrike
    • Two gene
    • Second gene effective on fall armywor
    • Weak concentration of Bt in terminal (original work Beltwide was at Prattville
    • Scouting technique must be different than Bollgar
    • Under pressure, WideStrike required overspray with pyrethroid
  • Bollgard II
    • Two gene
    • Reduced bollworm escapes by about 80-90% over Bollgar
    • Broaden caterpillar spectrum over single gen
    • Second gene has long term benefit in resistance managemen
    • No refuge requirement
  • Bayer Twin Link
    • Two Bt insect genes and
    • Caterpillar effectiveness between WideStrike and BGII
  • Bollgard III
    • Contains third insect gen
    • Third gene not Bt so has different mode of actio
    • Should provide long term caterpillar resistance managemen
  • Lygus Genetics
    • Early stages of developmen
    • Evaluated 40 lines of genetically altered cotton for lygus in 2011, Prattville
F. New Generations of Pyrethroid Chemistry
  • Early 1990’s documented that not all equal for fall armyworm control. Karate, bifenthrin (Capture) superior
  • More recently developing data to show that bifenthrin not as effective on bollworm species
  • Pyrethroids not effective on the brown stink bug; however, bifenthrin superior to other pyrethroids
  • Some generic pyrethroids may not be as effective as the “brand” names
G. Evolution of the Shifting Insect Complex Following BWE and Bt Varieties
  • Current low spray environment
  • Development of boll feeding bugs and sucking pests (plant bug and stink bug complex, leaf footed bugs)
  • Role of IGR Diamond for plant bug management
  • Reemergence of spider mites as an economic pest of cotton (influenced by movement from Temik to seed treatments)
H. Stink Bug-Dominant Insect of Alabama Cotton

  • Work to develop best scouting technique
  • Now sample 10-12 day old bolls for internal injury
  • Worked with other southeastern states to develop a “dynamic” threshold for stink bugs. One that considered the number of bolls at risk at a given point in the season
J. Insect Management in Conventional Cotton Systems
  • Conducted research on which new insecticides provide the best caterpillar control
  • How to best manage beneficials, plant bugs, and early mid-season pests
  • Trials indicate that weed control costs similar in both conventional and generic systems
  • Tobacco budworms are the budget buster in a conventional system
  • Can make only one TBW spray per season with the savings from no insect technology fee
  • Discovered role of fire ants in both conventional and generic systems
K. Role of Fire Ants in Cotton
  • Are the dominant beneficial in Alabama cotton today
  • Not only important in conventional systems but also reduces escapes in Bollgard and WideStrike (Example: Mississippi consultants spray BGII on % egg lay)
  • Some chemicals suppress fire ants more than others (Centric, Steward, pyrethroids, imidacloprid)
  • Dr. Tim Reed and I conducted a project at Prattville last season (Poster Presentation)
  • Results show less boll damage on both conventional and genetic cotton with fire ants in system as opposed to no fire ants
Numbers on the side represent the number of worm damaged bolls per 45 feet.
Impact of Fire Ants On Bollworm
Damage in Alabama Cotton
L. Emergence of Sporatic Pests

  • Grasshoppers have increased in importance in reduced tillage environment
  • Pose risk to stands
  • $$$ greater investment in front end of season production cost now compared to old days
  • Immature G.H. easy to control, adults difficult
  • Ideal timing is when “burning down” in early spring
  • Most all labeled chemicals, including the IGR (Dimlin), work on immature at low labeled rates
M. Study of Bollworm Resistance to Bt

  • Lab studies conducted by Dr. Bill Moar, who has since moved onto the Monsanto resistance management team
  • His findings indicate that bollworms have the ability to develop resistance to Bt in the lab– but they usually are unfit for survival when they do so.
In Summary
The ACC did not fund all of every project completed over the past 20-30 years. However, your support often made it possible to be in a learning situation on insect outbreaks; new emerging pests/problems and on projects/trials that were not directly funded. Some of you may remember that my grants in earlier years were entitled “To look at New Chemistry and Technology and Determine Where They Best Fit in Alabama Cotton Production”. This allowed us to know more about the strengths and weaknesses of new chemistry/technology than even the companies bringing them to the market. Cotton insect research is unlike most of the other disciplines in that it requires much more hands on involvement. Often times, support from multiple sources had to be pooled to provide the labor and travel to conduct cotton insect trials. Fifteen to 20 trips to a research site are often required between planting and harvest. This is especially true with the genetic technology under development.

A final point I would like to make is that we in Extension have conducted basically all the cotton insect research since the early 1990’s without an Ag Research station counterpart. We feel that we have kept Alabama growers up-to-date and often ahead of the curve in cotton insect management, when compared to other states. Much of the credit goes to the support we have received from the Alabama Cotton Commission.