How to monitor and when to control the early abundance of thrips on soybeans fields?

Raul Villanueva, Extension Entomologist, University of Kentucky

Insect Description and Damage 
While monitoring an experimental soybean field in Princeton, I have not noticed major insect pest problems during the earlier stages of soybean growth, with the exception of thrips. Thrips are tiny, slender insects (less than 1/16 inch) with characteristic fringed or bristled wings; they have rasping and sucking mouth parts. During feeding, mouth parts scrape the epidermis of the soybean leaf (it can damage flower, bud, or fruit on other plant species) and then suck plant fluids. In addition to these plant feeding thrips, there are beneficial thrip species that prey upon small insects and spider mites. 

Warning, Armyworms Spotted in Pastures!

Doug Johnson, Extension Entomologist, University of Kentucky

Fig. 1. Armyworm

Capture of armyworm (AW) in the IPM pheromone baited traps still remains below average. Nevertheless, this does NOT mean that there are no AWs around. While economically important populations of AW are not (yet) a wide spread problem this year, the fact remains there certainly are infested fields. The question becomes which fields are infested with an economically important population size? There is only one way to know that, and that is to scout. We do know that AW feeding on pasture grass has been reported from Butler Co. and I expect, that if one looks, infested fields will be found in other areas.

Fig. 2. Fall Armyworm

Do not confuse armyworm with fall armyworm or for that matter beet armyworm, army cutworm etc. These common names can be misleading as they sound similar but represent completely different insect species, whose ’ common features are only that they often move in large masses (hence the descriptor “Army” worm) and they feed on similar plants,generally grasses such as pastures, and large grasses such as wheat, corn, sorghum, and millet.

Most often confused in Kentucky are armyworm and fall armyworm. Armyworm also called “True armyworm” is a spring pest for Kentucky and most of the eastern U.S. It overwinters as far north as Tennessee and probably southern Kentucky, then migrates northward in the warm months. Fall armyworm (FAW) is a late summer to fall pest in Kentucky. This is due to its’ inability to tolerate cold weather, requiring it to overwinter in Texas, usually south Texas, then migrate to Kentucky and northward in the warmer months. During our current time of year armyworm is the threat to pastures, wheat and corn.

Armyworm Moth Flight Increases in Princeton and Lexington Traps.

Doug Johnson, Extension Entomologist

The capture of armyworm moths in the UK-IPM traps increased significantly in both the Lexington and Princeton traps for the trap week ending Friday May 3^rd. See the Graphics at:

http://www.uky.edu/Ag/IPMPrinceton/counts/taw/tawgraph.htm


In both cases the increase is large and is probably related to the warm weather over this period. Nevertheless, these captures will just bring us back to about average (Lexington) and a bit above average at Princeton. It is too soon to know if these increases point us to an outbreak population.


Even though trap captures have been reduced, and late this year compared to last, we need to remember that these pests are out and about. Just because the trap captures are low and late does not mean that there will not be a problem in some fields. Corn planting and growth are behind as well, and we are (at this writing Fri 5/3/13) about to enter another wet cool period. This type of weather will once again slow down planting and corn growth, and tends to favor armyworm development. Even though the risk is not above average, there is some risk just the same, and corn and wheat should be scouted for this pest.

I have had one report from far west KY that sound like armyworm on struggling 1-2 leaf corn though the diagnosis is not definitive. Just the same, it is best to remain alert for this pest.

Armyworm & Cutworm Moth Flights Rather Ordinary

Doug Johnson, Extension Entomologist, University of Kentucky

Black cutworm moth

Capture of both armyworm and cutworm moths have decreased during the previous trap week. At present the data indicate that neither pest is set for a big outbreak. Of course this can change especially if we get a sustained week of good weather. This does not mean that there are no pests around, there certainly are. Nevertheless, flight patterns compared to the rolling five year average do not show any sign of an elevated risk of outbreak.


 

Armyworm moth

Even though we have a good outlook for the short term we still need to remember that “only about 15 percent of corn has been planted which is well behind last year’s 73 percent and the five year average of 32 percent” (KY Weekly Crop & Weather Report Apr. 22, 2013). Remember, both black cutworm and armyworm are migrating to KY from more southern states, and the timing of their migrations are dependent upon temperature just as are planting and corn development. So it is still very possible that larger populations of either or both of these pests could show up in the early vegetative stages of corn development.So, for the moment things look good, but one best pay attention to future developments.

Tracking moth flights isn’t your only preparation option. With both insects but black cutworm in particular providing a weed free seed bed for at least two weeks prior to planting can make a big difference. Early preplant herbicide programs have shown a positive impact in the prevention of cutworm and common stalk borer infestations. Removing weeds especially grass weeds by whatever mechanism, ahead of planning is a good strategy for these early arriving insects.

Armyworm Flight Begins

Doug Johnson, Extension Entomologist

 

  Figure 1. Armyworm moth Spring must really be here as armyworm (aka true armyworm) moths have taken flight. Only a few moths have been captured thus far, but it does signal the beginning of insect season in the field crops and the current year’s capture is in line with the outbreak year of 2008. It is still too early to get real excited but important enough to be aware.

In Kentucky, armyworm can be an important pest of corn and wheat. Corn products that contain a Bt trait that provides protection from caterpillar feeding (See: Insecticide recommendations for corn:   http://pest.ca.uky.edu/EXT/Recs/ENT16-Field%20corn.pdf, pages 6-7) will likely be protected. However, non-Bt types including field corn refuge, popcorn, food-grade corns, and sweetcorn along with wheat will be at risk.

We are several weeks from any damage caused by armyworm as the adult moth is not the damaging stage. Monitoring this stage just gives us a “biofix” or heads-up that the pest is about. It is the caterpillar in which we are interested. You may want to check the flight graphs each week for the progress in this population. These may be found at:  http://www.uky.edu/Ag/IPM/ipm.htm. It only takes a few seconds to check and this can give you an idea of the relative risk of this pest for this season. On the graph you can see displayed the current year’s capture (green), the rolling five-year average (blue), and known populations that have resulted in outbreaks (red and/or black) This will give you a rough estimate of the current year’s relative risk. As these graphs represent moth flight, the relative population size can be seen before the damaging stage, the caterpillar, develops.

If populations appear to be indicating an elevated risk, I will use a temperature-based model to predict when the caterpillar stage will appear. This model will NOT predict which fields will be infested. One must scout fields to know if the armyworm is present, but the model will provide an estimate of when the field should be scouted. Remember, the model predictions will be based on the capture and temperatures at the UK-REC in Princeton (Caldwell Co.) KY. In areas to the south and southwest of the UK-REC caterpillar development will be ahead and areas to the north and northeast of the UK-REC will be a bit behind.  I will post, and you may review, the results of these model runs each week in this publication. So, if you are the pest manager for wheat or corn this spring, keep yourself tuned to this outlet for “Early Warnings” about this pest.

Fall Armyworm- Follow-up on the Fall 2012 Infestation.

Doug Johnson, Extension Entomologist and Patty Lucas, IPM Specialist

Fall armyworm moths.

We know a number of you had to deal with the large infestation of fall armyworm we saw this past September and October. Infestations were reported in grass hay, & pasture, newly established or renovated forage grasses, wheat and rye cover crops, as well as in late maturing soybean and early planted wheat for grain. This was an unusual event, perhaps the largest population of FAW in recent memory.

We would like to gauge the spread and impact of this pest in Kentucky. To aid us in this we have prepared a short survey on the Survey Monkey web site. This is a short survey and will not take you more than a few minutes to complete. We would appreciate it very much if you would provide us with your experience. You can reach the site at:

https://www.surveymonkey.com/s/VCGX5QL

This may not be a clickable link in the blog. If you cannot click on the address then please copy and paste  the address into your browser.

No information that will identify you will be collected by the site. There is one location in the survey where you may leave an email address to follow up if you so choose. Those addresses will be held in strict confidence. They will NOT be shared with anyone else, and will be stored offline.

We thank you in advance for taking just a few minutes to help us understand the impact, and distribution this insect had in 2012.



Fall Armyworm in the Near Term.

Doug Johnson, Extension Entomologist


I am still receiving calls about fall armyworm (FAW) primarily as they affect pastures and especially reestablishment of grass fields and waterways. Most people are able to get control relatively easily, once the infestation is found; and by now quite a few folks are looking!

We have a few pieces of good news. The capture of moths in the UK-IPM trap at Princeton, KY has decreased significantly to 69 moths / trap-week. Additionally, we have a forecast of very cool temperatures and perhaps some significant frost. Both of these will have a generally debilitating effect on the FAW population.

It is quite reasonable to assume that FAW populations will decrease over the next week or so. Nevertheless, it is impossible to predict what will occur in a specific field or portion of a field. That is all completely dependent on how cold it gets and for how long that cold lasts. This is especially important for producers pushing up against the planting date window for newly seeded grasses. If you must plant / renovate in the near term then be sure that: 1.) There is no uncontrolled FAW infestation in your field. 2.) Make sure you begin checking your newly seeded grasses as soon as they begin to emerge for the presence of a new infestation.

For those producers planting winter wheat, waiting until after the Hessian fly free date, which from the date of this writing (Fri. 10/5/12) would be another week to 10 days, depending upon where you are located, could reduce your risk substantially. Again, this is almost completely dependent upon the weather, especially temperature, during this time frame.

Temperature forecast over the next ten days is about normal. There is a chance of frost on Sat. 10/6 and Sun. 10/7 but after that the temperatures will moderate once again. This weather is certainly not preferential for FAW growth and development and I would expect a continual decrease in the population size. However, I don’t see any immediate event in the next ten days that will remedy the problem for the season. So, for the time being, those with susceptible crops (all small grasses) should keep checking for the presence of this pest.

Fall Armyworm Moth Flight Up-tick…. But why?

Doug Johnson, Extension Entomologist

After a drop last week to 487 moths/trap-week from the peak capture of 675 moths/trap-week, capture of fall armyworm (FAW) moths in the UK-IPM pheromone baited trap has increased  to 605 moths/trap-week (See Figure 2.). This indicates a continued and elevated risk of infestation by this pest for the next several weeks. This up-tick in moths captured does not indicate another generation. It is more likely that the cool weather in the previous week reduced the number of moths flying and the warm up has done just the opposite. If this is the case, then last week’s moth capture should have been a bit larger and this week’s a bit lower, making the curve appear a bit more normal.

Figure 2. 2012 FAW Capture.

 This spiky appearance to the graph is just due to a small number of data points and a wide span of time (a week) between data points. What is most important is the fact that there are still a great many moths flying and females will still be laying eggs for several more weeks unless there is a drastic change in temperatures. Caterpillars resulting from the egg lay of the current moth flight have already begun to appear.  I expect that egg lay resulting from the moths represented by this week’s data point will continue into the first week of October. Caterpillars resulting from the current egg lay could be active through the entire month of October. This is, of course, completely dependent upon temperature.

We would normally expect for the threat from FAW to end on or about the first killing frost. Certainly we have eggs and caterpillars, in various stages of growth, currently in the environment that can last past the average first killing frost date. This does not even account for the moths that are currently flying, mating and laying eggs.

Thus, small grass crops will remain at risk to infestation by FAW until the weather changes enough to stop the cycle.  This usually occurs with a “killing” frost.  Looking at Mr. Tom Priddy’s short-term forecast, this should be about the normal Oct. 22 date.

 FAW is a tropical insect and cold weather will solve the problem. Nevertheless, experience has shown me that light frost will not do the trick, even with air temps near or at freezing.  It’s because at the soil / air level, especially in no-till fields, temperatures may remain above freezing. This is certainly true for clear sunny days, when the soil litter can obtain heat from sunlight.

Our current change in weather to rainy cool temperatures will slow this insect down. In addition these conditions will select in favor of the cool season grass that have recently been planted. You will need to continue scouting of these new stands, but weather is looking more favorable.

At risk crops remain the same, with the possible exception of soybeans. Most of these should be beyond the stage that leaf damage will be important. Sowing or renovating pastures, waterways, and cover crops with any small grass needs to be scouted for FAW.  Sowing wheat earlier than the Hessian Fly free date will increase the risk of FAW problems. Even sowing on or after the Hessian Fly free day may not provide control if the normal killing frost is late. 

Having talked to many producers, consultants, and farm service personnel, it is apparent that the problem remains in detecting the infestation. Control, once the infestation has been spotted, does not seem to be a problem.

Several common questions continue to come up:

Q.  If I spray for the FAW now, will that prevent a future infestation?

A.  No. You will probably get some residual activity from your insecticide, but if the weather stays warm, the insect’s life cycle will outlast the residual. As the weather grows cold, the application will be unneeded.

Q. If I treat my wheat seed with an insecticide, will that control FAW?

A. No, the rates we use on wheat in KY are meant to control very small sucking insects like aphids and Hessian flies. Think how much more massive a FAW caterpillar is than an aphid. This is a rate problem, not whether or not the insecticide would kill FAW.

Q. My pasture is mowed off. Has FAW killed my pasture?

A. No, it is very unlikely that FAW will kill an established stand. You will lose your yield, e.g., hay, stockpile grazing, etc.  There is little difference in FAW and cattle feeding; FAW just have smaller feet!

Q. FAW has eaten up my newly sown pasture / waterway / wheat; has it killed my seedlings?

A.  This is impossible to answer without waiting & watching for re-growth. FAW does not usually kill established grasses. However, if the root system is not well established, some seedlings may die.  My experience with wheat tells me you should be careful about reseeding.  I have seen FAW graze off a field, making it look dead, then the producer reseeding as soon as possible and ending up with a “double seeding”.  This results in many problems in the spring.

Fall Armyworm Moth Flight – Has begun to drop, but still plenty around!

Doug Johnson, Extension Entomologist

Figure 1. 2012 Capture of FAW

The second flight of fall armyworm (FAW) has begun to drop as indexed by the UK-IPM pheromone baited trap in Princeton, KY. Nevertheless, the capture for the trap-week ending Sept. 20, 2012, is still greater than the peak capture during the outbreak of 2007. (See Figure 1.) So, hopefully, we are on the downhill side of this problem, but there will still be plenty of moths to lay eggs over the next couple of weeks.

Producers, consultants and farm service personnel are still calling to report infestations and ask questions. There does not seem to be much problem with obtaining control once an infestation is found, but many folks are still not finding the infestations until considerable damage has already been done. Certainly, most callers are interested in what is coming next. Although the moth capture gives us a heads up and an indication of the level of risk, they will never tell us what is happening in a given field.

Our current weather may tend to extend the time the caterpillars are present. Our cooling temperatures are not cool enough to hamper the worms, but their development may slow down, increasing the days they will be in the damaging stage.

The crops at risk remain the same. Grass crops (pasture, hay, lawns) still remain in danger. Still, soybean problems appear to be coming from the caterpillars “marching” out of grasses in to the beans. Don’t neglect to check a field interior now and again. FAW will lay their eggs in soybeans, but grasses are by far the preferred egg laying site.

Anyone planning to plant wheat, rye, or renovate / restore any “small” grass pasture or hay field should give strong consideration to waiting for a while longer to seed. Experience tells me FAW caterpillars will be around until frost, even if not in the large numbers present now.

Fall Armyworm Moth Counts Continue to Climb!

Doug Johnson, Extension Entomologist

Capture of fall armyworm (FAW) moths has increased for the second week in a row, and this week by a huge margin (Figure 1.). Not only has an unprecedented second distinct FAW flight begun, it has surpassed this year’s previous peak in size. The August flight which reached 549 moths / trap-week for the trap-week ending Thur., Aug 16th, now stands at 675 moths / trap-week for trap-week ending Sept 13, 2012. Will it go higher? Only time will tell.

In addition to the numbers of FAW moths being captured, there is a second situation that gives me pause. This 2nd flight peak will be earlier in the season than we normally see, if one occurs. If the current numbers turn out to be the largest capture, then the peak will be approximately two weeks earlier than we would normally expect. Putting this in perspective, if we have an average frost date of Oct 22nd , this flight has approximately 5 ½ weeks for the caterpillars to develop and feed on our crops as opposed to a more normal 3 weeks. If frost is late this interval could be even longer.

Remember, the graph above represents MOTH flight. Moths are not the damaging stage of this insect. These moths were captured because they were seeking female mates. Once mating and egg lay has occurred, we will begin to see very small FAW caterpillars. This is the beginning of the damaging stage. This will likely take a week, perhaps two, depending on temperatures. Of course, further south and west (toward the upper Mississippi River bottoms) caterpillars will appear sooner. Further north and east (in the western 1/3rd of KY), caterpillars will take longer to appear. Fortunately, the traps in Lexington have just this week captured FAW for the 1st time this year; and the numbers are small. I doubt that there is any unusual risk in central and eastern portions of our field crop / pasture-hay production area.

Remember, as well, that these trap counts will NOT predict what will happen in an individual field. There is really no easy way to detect the presence of this pest. One must go to the field and look for their presence / activity. I would start by sweeping in grasses that have received enough rainfall to start re-growth. This will be a preferred egg laying location. FAW will lay eggs in soybeans, but they are not the preferred host. If this generation acts like the last, most soybean infestations will start with worms moving from grass waterways, roadsides & pasture/hay fields.

Crops primarily at risk will be newly planted wheat, pasture / hay production and very late maturing soybeans.

There is really only one thing that can bring this cycle to a halt….cold weather. FAW is a tropical insect that cannot overwinter in KY. In fact, under historic conditions, FAW cannot overwinter outside the gulf coast areas. So, vigilance will be needed until a hard frost stops their northward migration. Certainly, this is not the year for early planting of wheat.

Also, see Kentucky Pest News No. 1318, Sept. 11, 2012 at:

http://www.ca.uky.edu/agcollege/plantpathology/extension/kpn/current.html

and the Wheat Science News Vol.16, No.5, Sept. 7, 2012 at:

http://www2.ca.uky.edu/wheatscience-files/Sept_6_2012_Wheat_Newsletter.pdf

for the article: “The Effect of Insects on Wheat Planting Decisions” for a more complete look at FAW and other arthropod pests on our upcoming wheat planting season.

Fall Armyworm Moth Flight Numbers Begin to Rise Again.

Doug Johnson, Extension Entomologist


The number of reports of fall armyworm (FAW) infested fields has slacked off for the present. Unfortunately, I do not think this problem is over for the year. I believe our IPM pheromone- baited traps are supporting this notion with an up-tick in captures this week.

Notice up-tick in green line.

If we look at the FAW moth captures for the year so far (Figure 1.), we can see three telltale signs. All three of these may be found in the relationship of the 2012 flight (Green line) to the 2007 outbreak population (Red line) and the rolling five-year average (Blue line). The 2012 flight of moths is: 1. much earlier, 2. much larger, and 3. appears to be starting to climb, indicating a second moth flight. None of these is absolutely definitive that we will experience a second economically important worm population, but they certainly indicate that we should be watching for one. That certainly seems to be the opinion of my colleagues in states to the south of us, and they experience FAW more often than do we.

We will not know until we see the moth flight numbers for the trap week ending Thursday, Sept 13th, or perhaps even the trap week ending Sept. 20th whether or not we have a second and threatening population. To my knowledge, there is no precedence for this in KY. Certainly we have seen FAW linger until frost, but we have not seen them do this in widespread large numbers.

When viewing these graphs, please remember that you are looking at moth capture. Moths are not the damaging stage in this insect. Moths (adults) are simply responsible for reproduction, dispersal, and egg lay. The resulting worms (damaging stage) will appear after a 1-2 week delay from the moth flight.

See the article: The Affect of Insect on Wheat Planting Decisions, in Kentucky Pest News at:
http://www.ca.uky.edu/agcollege/plantpathology/extension/kpnindex.htm
 for a look at the possible impact of insects, including FAW, and mites on the 2012 wheat crop.

Also see the Wheat Science News Letter at:

http://www2.ca.uky.edu/wheatscience-files/Sept_6_2012_Wheat_Newsletter.pdf

for Insect & other pest considerations and agronomic information related to the 2012 planting season.

Capture of corn earworm moths in IPM pheromone baited traps at UK-REC, Princeton (Caldwell Co.) Ky in 2012.

Doug Johnson, Extension Entomologist

CEW caterpillar and damge on soybean.

Corn ear worm (CEW), also known as soybean podworm, are currently active in soybeans. This is a direct damage pest as it feeds on pods, seeds, & petioles. You are unlikely to detect this pest by checking for defoliation because it does not feed much on leaves. There is no sure way to detect this pest in your soybean crop except to scout for it. This means sweeping or direct visual examination of the pods.

CEW may occur in many color phases. It sometimes appears very dark, almost black, to brown to red and green. The green color phase is most often seen when feeding in soybeans. When fully grown, the larvae are about 1 ½“ long. They are marked by alternating light and dark stripes running the entire length of the body. These stripes are not always the same from one caterpillar to another. Usually a double dark stripe will run down the middle of the back.

You can certainly look for direct damage feeding on the pods to see if they are causing damage. In rows narrower than 30”, sweeping with a 15” sweep net is about the only way to measure this pest. The threshold is 9 worms per 25 sweeps.

Capture of CEW moths at UKREC 2012

We do know that corn earworm moth flight has been increasing and populations are greater than we normally see. Moth capture in our IPM pheromone baited traps at the UK-REC in Princeton is shown in Figure 2. Remember, these are moth counts and moths are NOT the damaging stage. Caterpillars will appear about a week after the moth flight. In 2012, moth numbers (green line) are greater than the rolling five- year average (blue line) so we are at an elevated risk of damage from this pest compared to most years. However, trap captures will NOT tell you what will happen in an individual field. Only field sampling will help you establish whether or not a threshold has been met. Moth flight numbers will give you a week or two heads up on what might happen.

If insecticide control is warranted, you may find products listed for control of CEW in soybeans online at: http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html or from your County Extension Office. Be wary of spraying too early, you may kill the predatory insects that are providing some natural control and miss the actual pest.

Cutting soybeans for Forage? Consider some Insects!

Doug Johnson and Lee Townsend, Extension Entomologists.

Margined blister beete on soybean.

Some folks have been asking about cutting soybeans to be baled and used for forage. In general most insects in soybean are not a problem. However, blister beetles can be. Blister beetles are commonly found in soybeans thought not in large numbers. In my plots this year the black margined blister beetle has been the most common, though others will occur.

This insect and its close relatives the ash gray and striped blister beetles are infamous as a contaminant of alfalfa hay for their effect on animals, particularly horses. They are found in soybean for the same reason as alfalfa, they are attracted to and feed on blooming weeds.

Green Cloverworms Appearing in Large Numbers in Soybeans.

Doug Johnson, Extension Entomologist

There are some unusually large populations of green cloverworms on soybeans scattered around the state. This is a very common insect in soybeans which always has the potential for economic damage, but very rarely causes economic damage. The populations I have seen thus far are not at the economic threshold, but were much larger than I am used to seeing. It makes sense to look at your soybeans, especially late planted or slow developing beans.

Green cloverworm caterpillar on soybean stem.

Green cloverworm is easy to find and easy to identify. These worms are light green with two thin white stripes along each side of the body. When fully grown, these slender worms are 1” to 1-1/2“ long. They have only three pair of prologs in the center of their body. Most of the other caterpillars in KY grown soybeans have either 4 or 2 pair of prolegs. Green cloverworm will become very active, wiggling and looping when disturbed.

These pests are foliage feeders. They will strip the leaf tissue from between the veins leaving the veins, petioles and stems behind like a skeleton.

It takes a great many of these caterpillars to cause an economic problem. Economic threshold (ET) depends not only upon the number of green cloverworms, but also on the stage of the plants, the value of the beans, and the cost of treatments. ETs may be found in:

IPM-3, KY IPM Manual for Soybeans at: http://www.uky.edu/Ag/IPM/manuals.htm and

ENT- 13, Insecticide Recommendations for Soybeans at: http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html

These insects are not very hard to kill. It is most important to detect them before they reach threshold and determine if control is needed. If you find them only after the damage has been done, you can kill them, but you can’t put the foliage back on the plants!

Fall Armyworm Moth Flight Increases, worms sited!

Doug Johnson, Extension Entomologist


Capture of fall armyworm (FAW) moths in UK-IPM pheromone-baited traps has increased substantially over the last week. Until recently, there had been no FAW moths captured at the UK-REC in Princeton (Caldwell Co.) and only small numbers in Cam Kenimer’s trap line in Fulton Co., KY. In the trap week ending 9 Aug. 12, the capture increased from zero to 131 moths / week at the UK-REC, though the Fulton Co. trap counts remain low.

It is difficult to know what the increase at the REC might mean, however, a producer in Caldwell Co. (the county in which the REC is located) has seen a small number of FAW crossing a road. Additionally, reports from counties further east and south report FAW infestations in pastures (they must have gotten some rain!!!). Add to this reports from our colleagues in states to the south, indicating increases in FAW activity in areas that have received recent rains; and I think this adds up to checking to make sure they are not present in your fields.

At this time of year FAW are primarily a risk to soybeans and pasture / grass hay fields. They would also attack corn, but we are too far along for this to happen in our major corn growing area. Nevertheless, this insect can be quite voracious so producers of soybean and pasture / grass hay are encouraged to check your fields to look for this critter.

FAW is a migratory pest in KY and is only an occasional pest of soybeans; but it can cause serious damage if infestations are large. Soybean is not a preferred host crop, but it may be infested especially in years when grass crops are not available. Given our unprecedented drought that is certainly the case this year. This is primarily a defoliating pest but can feed on pods as well.



FAW on corn leaf.



Newly hatched FAW are white with a black head, but the body darkens as it grows. Full-grown larvae are up to 1 1/4“ long, have black bumps, and may be light tan to dark green. The black head will have a distinct inverted “Y”.

Thresholds for this pest in soybean are not well established in KY. Like corn earworm, if sampling in wide row beans with a 3’ shake cloth, the threshold would be an average of 2 worms per row-foot. If sweeping narrow rows with a 15” sweep net, an average of 9 larvae per 25 sweeps would indicate a need for control.

Thresholds for FAW in pastures / grass hay fields are also not established. Clearly the insect can do great damage in some situations. In states further to the south of us 4-6 or 5-7 worms per square foot are used as the economic threshold. Though the season would be earlier and the grass variety different, that is probably as good as starting place as any.

If insecticidal control is required check ENT-13 (for soybeans) or ENT-17 (for pasture / grass hay) for a listing of registered insecticides. These publications may be obtained from your county extension office or on the web at:

                  http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html

Corn Earworm Moth Counts Increasing Significantly.

Author: Doug Johnson, Extension Entomologist

Capture of corn earworm moths in IPM pheromone-baited traps in Princeton, (Caldwell Co.) KY and in Fulton Co. KY have taken a significant increase over the past two to three weeks. This follows on the heels of warnings of corn earworm problems in states south of KY.

The counts in Cam Kenimer’s Fulton Co. traps are by far the largest, with a capture of 547 moths on 8/5/12 and 486 on 8/12/12. Numbers are increasing in Princeton, too, with 200 captured during the trap week ending 8/2/12 and 206 for the week ending 8/9/12. This is a substantial increase compared to the rest of the year. The increase also came earlier in the year by several weeks and is much larger when compared to the rolling five year average. ( See:

http://www.uky.edu/Ag/IPMPrinceton/counts/cew/cewgraph.htm)

These insects are likely coming out of corn that is maturing and will be looking for another host, probably soybean on which to lay their eggs. The moths are not the damaging stage, but in a couple of weeks, their offspring will appear in the form of caterpillars.

The first really big jump in capture was in Fulton Co. on July 22, but that capture is only about 1/3 of the most recent capture. Using July 22 as a starting date, small larvae to medium larvae could already be present. Larvae from moths caught over the last couple of weeks should come in a steady stream.

With corn maturing and being harvested in most western KY areas, soybeans are the most likely field crop target for this pest. Of course these counts cannot predict what will happen in a particular field. Conversely, the captures are certainly above the rolling five year average so represent an increased level of risk. Areas in the south and west will be impacted sooner and areas in the north and east somewhat later. You should be scouting your soybeans NOW!

Newly hatched CEW larvae are translucent yellowish-white, but larger larvae have considerable color variation. When feeding on soybeans they tend to be light reddish- brown and large larvae are often green, yellowish or black with distinct cream colored bands running their length and their heads are usually orange.

CEW can consume foliage, flowers and pods of both full-season and double-crop soybeans. Economic threshold in wide row (30”) beans sampled using the 3’ shake-cloth method would be two worms per row foot. If sweeping (15” sweep net) narrow row beans the threshold would be an average of 9 caterpillars per 25 sweeps.

If insecticidal control is warranted, suggested insecticides may be found in ENT- 13 which you may obtain from your county extension office or on line at: http://pest.ca.uky.edu/EXT/Recs/welcomerecs.html