Early August Insect Update

It has been a number of days since we last reported on Alabama insects. So what has been happening? First of all, August has been dominated early-on with little insect activity other than the bug complex in cotton. Second has been the weather, we had sun yesterday, August 19, for the first time in about 10 days. During this period, rainfall has been measured in inches varying from low single figures to double digits, depending on the location. Up to 4 inches in a 24 hour period has been common. This has resulted in bridges and roadways being washed out and public schools closing during the beginning of the fall term. Agriculturally wise, sprayers have been unable to get into fields and aerial applicators are over booked. Fortunately, insects have overall been low with just a few exceptions. The bug complex has been over threshold in many but not all cotton fields. In the past few days the caterpillar complex has built to damaging levels in soybeans. Some fields have been sprayed by plane for the lep complex, primarily loopers and velvetbean caterpillars. The heaviest infested fields are those where growers just preventatively added a pyrethroid when they were applying a fungicide.

It has been my experience in research plots that an application of a pyrethroid just prior to an infestation of foliage feeding caterpillars is like throwing gasoline on a fire. We usually see much higher numbers of soybean loopers where a pyrethroid application has been made within the previous 10-14 days. My advice to growers is that if they feel they must add something to their fungicide, just add 2 or 3 ounces of a product like Dimilin which does not disrupt the beneficial insects.

Once we have a damaging level of foliage feeders the first thing we need to do is to quantify the species present and the numbers. Five to seven caterpillars per foot of row will usually result in 30% or more foliage loss and therefore require controls. Treatment thresholds for sweep nets on drill beans are not quite as well defined. However, 2 to 5 per sweep would likely require controls. As to species, velvetbean, green cloverworms, corn earworms (podworms) and stink bugs can all be controlled with a pyrethroid. However, if many soybean loopers are in the mix, then one of the newer lep materials will be required. These are, in chemical alphabetical order: Belt, at 2-3 oz.; Steward at 7 oz.; Intrepid at 4-6 oz.; Prevathon at 18-20 oz.; tracer or Blackhawk at 1.5-2 oz. per acre.

One additional thing should be added about soybean looper control, especially if application is by air. Looper eggs are deposited on the lower leaves of the plant, therefore they infest the plant deep within the canopy. As the larvae mature they feed upward through the canopy. In order for any of the newer chemistry to be effective, the leaf containing the droplet has to be eaten. Therefore, it may take several days to fully suppress a looper population. It has been my experience that the surviving  larvae behind application will be early instar larvae found lower in the canopy. Most of these looper insecticides are very rainfast and have long residual on the leaves, so don’t panic if you see a few small loopers behind an application.

I will be on research farms for the next several days and will get back soon if we see or hear of damaging levels of insects developing.

Kudzu Bug Q&A

by Xing Ping Hu, Extension Entomologist, Auburn University

What is a Kudzu bug?
The Kudzu bug is a small yellowish green lady-beetle-like insect. However, they are not a beetle, but a true stink bug with sucking mouths that sip the juice from plants.

They like to aggregate in clusters and release a very strong, foul odor that you can smell several feet away.

Kudzu bugs are also called lablab bugs, bean bugs, globular stink bugs, and bean plataspids.

Are they a new pest and where did they come from?
Yes, the Kudzu bug is a new pest for us in the United States. Many new people are being introduced to it every day. We will all have to learn the best ways to deal with it.

The Kudzu bug is native to Asia. Genetic markers indicate this bug was likely introduced from Japan.

When did they get here and how widely spread are they now?
It was first reported in Georgia in 2009 and spread to Alabama in October 2010. Since then, it has been spreading like wildfire. By the end of June, it has been confirmed in more than 430 counties across 9 Southern Region States. They are in all but 53 counties in Alabama right now.

How do they spread so rapidly?
Many factors aid in their fast dispersal:

• Hitchhiking on vehicles, airplanes, shipments of products and equipment, and even humans
• They are strong flyers themselves, capable of flying at least a couple of miles
• They are attracted to white and lightly-colored surfaces
• Propensity to migrate
• Diverse and flexible life history and rapid population growth rate
• Availability of primary hosts – kudzu plants and soybean crops
• Most interestingly, the new finding in my lab shows a majority of the adult females become fertilized before overwintering. A single pregnant female can lay egg masses in a new location without the presence of male.

What plants do they infest?
Kudzu bugs are leguminous plant feeders. Their primary host is kudzu plants; that is how they got their name. Of the other leguminous crops, they prefer soybeans to vegetable beans and wisteria vine.

However, they must feed on kudzu or soybeans to be able to reproduce. It is common to see them aggregate and feed on non-legume plants in early spring and late fall when leguminous plants are not available.

If they have been in AL since 2010, why the sudden population outbreak in soybean crops this year?
During the first year of invasion, the population was basically limited to kudzu patches. However, because of the exponential growth, overcrowding populations started to move into soybean fields in 2012 and reached peak outbreak this year.

What is the pest status of kudzu bugs?
They were first considered a nuisance pest in residential areas, but are posing much greater threat than previously thought. In Asian countries, it is a serious pest of soybean and vegetable beans. Here in the United States, besides yield loss of soybeans, it poses threats to international trade of agricultural products to Central America, and is an urban nuisance.

What damages do they cause in soybean crops?
They are slow feeders, sucking plant juice and gradually drawing down a plant’s vigor. They do not eat holes in leaves and do not take bites from pods or seed.

When do kudzu bugs move onto soybean plants and how long they stay in soybean field?
It depends on whether you have early, middle, or later soybean crops and the climate. In 2013, we observed adults of an overwinter generation move to lay egg masses on early-planted soybean crops when they are about 1 ft tall. Nymphs appeared in late May and by the middle of June, nymph population had peaked across the entire soybean field. This was also the optimal time for control treatment.

You will see Kudzu bugs in the field until the soybean plants become unsuitable (not enough juice). Last year’s research showed that Kudzu bug population was greater in early-planted soybeans rather than later-planted soybeans. We are monitoring Kudzu bug population dynamics this year.

Insect and Crop Update for the Week of June 23

After going weeks with light to moderate thrips pressure, damage was heavy on 4-7 leaf cotton in early June, especially in SW Alabama.

Cotton was growing rapidly but thrips damage on true leaves was showing heavy damage from about the 4^th to 7^th true leaf. (Peanuts also were taking heavy damage during this same period.)

The thrips window is over now and we need to shift our focus to spider mites, aphids and the plant bug complex which includes tarnished plant bugs, fleahoppers and an occasional clouded plant bug.

Mites are primarily found in the TN Valley region of North Alabama and some treatments were being applied last week.

I noticed the first aphids on April planted cotton in central Alabama last Friday (June 21).

Plant bug numbers (adults) were down last week but nymphs are beginning to appear in our earliest planted cotton (mid-April). I would suggest using a sweep net to sample adults for the next 2-3 weeks, depending on the age of the cotton. As we approach first bloom I would switch to a drop cloth and concentrate on the presence of immature plant bugs.

Also, field men should now be looking at pinhead square set. Fields surveyed on June 21 were setting about 90% of the fruit. However, some plants had up to 30% square loss at that point. I believe you will find that migrating adult tarnished plant bugs will seek out the earliest planted and most lush cotton fields. My thought is that this cotton provides the best shade from the 95 degree temperatures, and is the best host for plant bugs.

While looking for pinhead square set I noticed a number of white eggs, likely tobacco budworms. They would not be a concern now, but in the old days it would have created a real predicament. Spraying for plant bugs during a budworm moth flight would have been expensive and also put the grower on a treatment treadmill for the remainder of the season. Sometimes we forget how well we have it compared to the pre-Bollgard years.

On another insect – a few stink bugs are already present in cotton. Normally we do not worry about stink bugs until about the third week of bloom, when we have bolls that are 10-12 days old. However, when stink bugs are present at bloom they will attack thumb sized bolls as soon as the bloom tag sheds. Any feeding to bolls this size will cause the boll to abort. Therefore, fieldmen need to be alert for adult stink bugs in early bloom cotton as they monitor for plant bugs with a sweepnet. Stink bugs will not damage squares or blooms but will seek out these first small bolls.

Since some of our corn was planted later than desired, stink bugs will likely remain with that host until the post roasting ear stage when the kernels become hard. At that time we may have a large movement into other crops such as cotton, soybeans and peanuts.

One word about Kudzu bugs on soybeans. Numbers of adults are out of site on many of our April planted beans. In fact, adult numbers are beginning to decrease in some fields now but numerous immatures are present, which is the trigger we use to treat the field. Fieldmen who have not experienced this insect may overlook these immatures when they are small. They will be a clear to greenish color and very small after hatching.

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

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.

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.

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

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.

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.

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.

Announcing Alabama Scouting Schools

Announcement: Alabama Cotton Scouting Shortcourses Meeting Sites and Dates

• June 12^th (Tuesday) 2012; Autaugaville, Alabama- County Agricultural Center
• June 13^th (Wednesday) 2012; Headland, Alabama- Wiregrass Research Center
• June 19^th (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?

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

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



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).

Bollworm
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.

Aphids
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.

Weather and Insects Affect Late Season Cotton, Soybean and Peanuts

The greatest impact on cotton during the past two weeks has been the lack of rainfall. Drought and intense heat has resulted in the shed of all fruit less than 10 day old bolls from the terminals of plants. This will tend to shorten additional boll production by 2 to 3 weeks and will likely reduce the “top crop” by 200 or so pounds of lint in many fields. Rainfall in the next 7 days would still help fill top bolls that are not mature.

As the result of the above conditions, the insect control season, especially stink bugs, is about over. A few southern green stink bugs can be found in late maturing fields or “swag” areas that remain green in more mature cotton fields. Thresholds for these would be 30-50% internal boll damage on 10-12 day old bolls. A few fields would still profit from stink bug controls.

Tobacco budworms have been extremely low all season but field observations and pheromone traps indicate an increase in the past week or two. Also, bollworm moths are abundant this week in the southern counties of the state.

Soybean Insects- Soybean loopers are at economic levels of 5 or more per row foot in some Gulf Coast area soybeans. Chemical choices (in no particular order) are: Intrepid, Steward, Belt, Tracer and Besiege (Coragen and Karate). Dimilin will give good suppression and long residual. On cotton, the same can be said for Diamond.

Peanut Insects- Scouts reported a mixture of foliage feeding worms in peanuts in Monroe County (S.W. Alabama) about 10 days ago. Many of these were controlled or either they have cycled out by now. This mixture was dominated by bollworm and fall armyworm (grass strain) species. Also in the mix were a few green cloverworms, loopers, and granulate cutworms. Pyrethroids gave nice control of this mix.

Aphid numbers continue to build, while most insects numbers remain at moderate levels

Insect conditions have not changed greatly in the past week or so. Aphids have continued to build in more fields. All other insects are low to moderate levels (mostly sub-threshold). These include plant bugs (including a few clouded plant bugs coming into the mix), bollworms, tobacco budworms and stink bugs. Most growers do not have enough of a single species to apply controls for. The two biggest surprises at this point in the season are the low number of bollworms and the low number of stink bugs in most fields. Numerous fields of conventional cotton still have less than 2 bollworms per 100 plants. Boll damage to stink bugs is less than 10% in most fields.

Most of the state has had abundant thunderstorms for several consecutive weeks. Cotton yield prospects have improved greatly and, if conditions continue, numerous fields have two bale plus potential. The two biggest limitations we now have are fields with “skippy” stands and too much late maturing cotton.

Later than normal aphid buildup may require more proactive treatments

More fields were reported with aphid infestations last week. Due to this later than normal aphid buildup, growers may want to be more proactive in applying treatments. Stress from aphids, where they are occurring in 2011, is overlapping early to mid boll set. We need to set all the fruit possible in the next two weeks.


Both the brown and Southern stink green stink bug species are present at some level in many fields. Cotton planted in April and up to mid May is already into the third to sixth week of bloom. This means that we should be using a low (10%) internal damaged boll threshold for stink bugs. Growers who chose to treat for aphids should consider stink bugs when selecting their chemicals or tank mixtures.

The flight of corn earworms from corn to cotton usually occurs the week of July 20 in central Alabama. This egg lay may occur up to 7 days earlier in south Alabama and 7 days later in the northern counties. This budworm flight will only be meaningful to those who have planted conventional cotton varieties. Older larvae observed last week were likely from budworm moths that occurred 1 to 2 weeks ago.