Update for the Week of August 4, 2014

The most significant insect event in the past week was the reports of plant bug tolerance to all labeled or recommended insecticides in the Tennessee Valley of North Alabama. Several of our most experienced consultants are reporting that all classes of chemistry are suppressing plant bugs but their presence and damage behind applications are still above threshold levels. This has required repeated sprays and now tank mixtures with two recommended insecticides. Under these conditions, input costs for cotton insects, particularly plant bugs, make cotton an unattractive crop option going into the 2015 season. Some areas of the mid-south have been dealing with this problem for several years. At this point, the Alabama situation appears to be confined to the Tennessee Valley area.

It has been my experience that once plant bugs get embedded in rank cotton in July, they have always been difficult to control, requiring multiple applications. So now, we have insecticide tolerance in addition to a coverage issue. Looking ahead I see a larger role for the IGR Diamond during the early bloom period in future years.

Now to a quick oversight of other insect problems on cotton and other crops; stink bugs, primarily brown, are requiring controls in some cotton fields. However, overall they are not as heavy and widespread as expected. Aphids are showing back up in some fields requiring controls. Spider mites are present in many fields. It seems like we get more calls about mite control following weeks of high temperature and dry conditions.

In soybeans we are beginning to see loopers as far north as Montgomery in older beans. So far they are only at about a third of a threshold level. Scouts are reporting an occasional corn earworm and velvetbean caterpillar in the soybean mix. The same holds true for peanuts.

Fall armyworms (grass strain) are on about every crop except cotton now. Hay, grasses, peanuts, soybeans are all experiencing the need for repeated applications for FAW. We could safely say that FAW’s have about worn out their welcome, even though they are easy to control. It seems like their preferred row crop is soybeans planted in wheat stubble. Some fields are now on their third infestation and replanting has been required due to near 100% defoliation.

In many ways, 2014 has been like “old times” to Extension entomologists with numerous phone calls about when to treat and what chemical to choose. We don’t feel like step-children to the weed resistance and disease issues this season.

Scouting crops is the first step in all insect management and control programs.

Final Insect Update of the Season

The Alabama row crop insect control season is rapidly winding down. The few areas that still need attention for a few more weeks are as follows. We need to protect bolls on June planted cotton from stink bug injury until the bolls are approximately 25 days old. We still have plenty of time left in the season to mature small bolls that are present from blooms the last week of August. On soybeans, stink bugs continue to reproduce and feed on pods. Late planted, June to early July, soybeans will be susceptible to stink bug feeding for several more weeks. Stink bug adults will leave other crops when they mature and seek out late planted soybeans as their last host before heading for overwintering sites. I expect to see high numbers of stink bugs in many of these late maturing soybean fields. The good thing is that one application to economic levels of stink bugs in both cotton and soybeans made now should hold populations below damaging levels for the remainder of the season. Stink bug populations currently contain both the brown and southern green species. A high rate of most pyrethroids on soybeans should give adequate suppression. Kudzu bug adults are still present in many soybean fields but they are not as numerous in most fields as they were back a month or so ago. Their numbers seemed to have peaked in April and May planted beans back in the late June to early August window.

Overall 2013 has been a light insect year in Alabama for most species. A summary of what I have observed is the following. For cotton, thrips were moderate to heavy. However, their movement from wild hosts to cotton occurred in May instead of April. Therefore, their damage period coincided with our mid-planting period cotton instead of the earliest planted as happens most seasons. Plant bugs, aphids and spider mites were very light overall. Bollworms and tobacco budworms were low to nonexistent, even in fields of conventional cotton. I have conventional cotton on three research stations spread across the central and southern areas of Alabama. One had to search very hard all season to find a single larva or damaged fruit. Stink bugs were the only cotton insect that occurred at damaging levels in most fields in-season.

In soybeans, Kudzu bugs were extremely heavy in many early planted soybean fields. This was the first year that many soybean growers have had to deal with the Kudzu bug. Others will likely have their first experience in 2014. When all is said and done, I believe we will be able to handle this insect with one, or at most two, well timed sprays. Late maturing beans will likely still see a big buildup of stink bugs in coming weeks as other crops mature and dry down. The foliage feeding complex of green cloverworms, velvetbean caterpillars and soybean loopers have been very light in 2013. This follows the most widespread infestations of the past 40 years last season. Podworms have been very light in soybeans for the past two seasons.

This has been a very unusual year rainfall wise. This may be the only season during my 41 years here as our Extension Entomologist where we had too much rain.

With these comments we will end our in season blogs unless something unusual shows up. I hope my comments have been helpful to those of you that are receiving them. Hopefully we can continue this blog, the Syngenta Insect Hotline, and our tweets during the 2014 season.

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.

Stink Bugs Showing Up in Fields

Based on calls from consultants during the past seven days, most insect attention on cotton in Alabama has now shifted to the stink bug complex. This appears to be the appropriate thing to do since no other widespread destructive insect is being reported and a high number of stink bugs are being reported from all the major row crops. This began with wheat during the spring months. Stink bug numbers later shifted to corn. High numbers have been reported in recent weeks in peanuts, with increasing numbers being reported in both cotton and soybeans.

If we back up and review the situation since the end of the 2012 season, this is as expected. Stink bugs built high numbers on soybeans late last season resulting in a high level entering overwintering sites. This past winter was mild and we did not have the excessive high temperatures or extended drought this spring to limit a 2013 population build up.

This complex included both the brown and the southern green species. In the more southern counties within Alabama, the leaf footed bug is also in the mix. Leaf footed bug damage is identical to stink bug damage to cotton bolls. The important thing here is that, control wise, they are more like the brown stink bug. Phosphide insecticides do a much better job in controlling brown stink bugs and leaf footed bugs than do pyrethroids. Growers will need to keep this in mind as they select their chemical for treatment decisions. In Alabama, escape bollworms on Bollgard and Widestrike cotton varieties have not presented a big enough problem to select a pyrethroid over a phosphate for stink bug control. Field monitoring between July 20 and August 10 will determine if that trend holds true for the 2013 season.

In a few weeks, as we begin to make more stink bug control decisions in soybeans, we will have to work more with the pyrethroid chemistry to suppress the brown stink bugs in the complex. Research trials across the south point to bifenthrin as their superior pyrethroid for brown stink bugs in soybeans. We can improve the percent control by using the higher labeled rates.

Back to cotton, here is how we suggest making treatment decisions. First, select a minimum of 25 ten to twelve day old bolls that are still soft to the touch and can be crushed by hand. Select more bolls from at least two locations from larger fields. Crush these bolls and observe for internal injury. Note, it may make this process faster by first separating the bolls with external feeding signs from those that have none. First, crush the bolls with external feeding only and determine the percent that have internal injury. If a threshold is reached, then the remainder of the bolls with no external feeding signs will not need to be crushed. Internal damage may consist of one or more warts on the inside of the boll wall, damaged seed or stained lint. Second, the decision maker needs to know how long that particular field has been in the blooming stage. Most stink bug injury and loss is coming during weeks three though five or six of bloom. This is the period when most harvestable bolls are being set.

In Alabama, I suggest using a 10% internal damage threshold during weeks three though six of bloom. An insecticide application will usually suppress stink bug numbers for seven to ten days unless a field borders another untreated crop with high numbers of stink bugs. If has been my experience that stink bugs do not move rapidly across fields like plant bugs as they reinfest. The first four to ten rows adjacent to corn or peanuts seem to get most of the migration initially.

In our heaviest stink bugs years, cotton in the coastal plains of the southeast have required up to four applications. Under most conditions however, only two or three sprays may be warranted.

One last thing I will mention today is that, in the past, stink bugs seem to cause more internal boll damage in wet seasons than in dry seasons. That being the case, and unless the weather changes, we need to be extra cautious of stink bug damage to cotton in 2013.

Update for the First Week of July

The Alabama cotton crop is growing rapidly resulting from abundant rainfall from multiple thunderstorms that have occurred during the last 10-14 days.

Insect wise things have been rather quiet on cotton but not the case with soybeans which I will discuss later.

Tarnished plant bug numbers have not increased as rapidly as expected in fields that I have observed. An occasional adult and or nymph can be found, depending on the age of the cotton. Migrating adults went to the earlier planted cotton first and have had time to now produce offspring. Cotton planted on April 10 is now blooming in Autauga County, Alabama.

To my surprise, I’m finding as many adult southern green stink bugs as I am adult plant bugs. We need to begin watching stink bugs in early bloom cotton. As I have stated before, these stink bugs will feed on thumb size bolls as soon as the dried bloom sheds. A huge stink bug population is waiting in corn. These adults will migrate to cotton, soybeans and peanuts as corn begins to dry down. This may be the largest population in corn that I have ever observed. There seems to be mating pairs in every corn plant at our research farms in Shorter and Prattville, Alabama this week. Most are the southern green species with an occasional brown in the mix. That will be to our advantage in a few weeks since the pyrethroid chemistry does a nice job controlling the green species.

The other insect that is building on cotton is aphids. They are clumped in terminals on occasional plants in numerous fields at present. These clumps will spread field wide before natural diseases wipe out the population. I would project that aphid population decline will not occur until around July 20.

The most intense insect pressure at present is Kudzu bug populations on soybeans in select fields throughout the state. Ten to 50 adults and over 200 immatures per plant can be found in many April planted beans. More adult Kudzu bugs are moving into beans from Kudzu daily. Beans will have to be scouted weekly for the remainder of this and future seasons. One to three sprays may be needed to protect beans this season. This will open the door to pod and foliage feeding caterpillars for the remainder of the season.

Information on the management and control of the Kudzu bug in soybeans has been posted in blog entries previous to this one and also on the Alabama Crops website (alabamacrops.com).

Kudzu Bugs Infesting Soybeans

Kudzu bugs (adults and immatures) infesting April planted soybeans on Auburn University research farm, Auburn, AL.

Immatures

 

Immatures

Adults

Adults

June 2013 Scouting Schools

2013 Alabama Scouting Shortcourses Announced

 

The following cotton scouting shortcourses will be conducted by Auburn Extension staff:

 

June 11: Autaugaville, Alabama, County Ag Center, Highway 14, for central and west Alabama

 

June 12: Headland, Alabama, Wiregrass Research and Extension Center, for southeast Alabama

 

June 18: Belle Mina, Alabama, Tennessee Valley Research and Extension Center, for northern Alabama

 

Cotton and soybean insects (description, recognition, life history and damage), seasonal occurrence, management recommendations and threshold levels will be discussed. Identification and scouting for cotton diseases will also be covered.

 

At the Headland and Belle Mina locations a special section will also focus on managing glyphosphate resistant weeds.

 

Commercial pesticide applicator recertification points will be awarded. Each program begins at 8:30 AM and will conclude after lunch with in-field visits.

 



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.

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.

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.

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.

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 15^th, 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.

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.

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.

Soybeans

Older beans mature and shedding leaves. Younger (wheat) beans filled pods rapidly during the past 2 weeks.

Soybeans

- Looper populations seemed to have peaked out. In most instances defoliation was between 5 and 20% where no controls were applied. Therefore, populations were below threshold level in most fields.

- Velvetbean caterpillars were found at damaging levels in one field of late maturing beans (R-4/5) in Baldwin county on September 12th. Velvetbean caterpillars are much more economic to control than loopers since pyrethroids do a nice job on VBC.

Soybeans

Loopers are the dominant soybean insect, up to 30% defoliation and damaging levels in some fields. A few velvetbean caterpillar and green cloverworms are in the mix. The “grass” strain of the fall armyworm does not appear to feed to a significant degree on soybeans. And, stink bug populations are not as high as anticipated.

Red banded stink bugs were discovered on the Wiregrass Research Farm, Headland, AL (Henry Co.) this week. Since they were found about 180 miles west of Headland last month, they likely may be present in other locations across south Alabama.

Soybeans

Economic levels of soybean loopers, fall armyworms (FAW) and velvetbean caterpillars (VBC) are as far north as Marion Junction in Dallas county and FAWs are occurring near Prattville in Autauga county. Soybean loopers, usually a southern latitude insect are occurring at all points within the state. Both VBC and FAW can be controlled with less expensive chemistry than can the loopers.