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Extension Entomology

Tag: greenbugs

Volunteer Wheat

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Frequent rain over the last few weeks has played havoc with volunteer wheat control.  Each rain seems to bring another flush of volunteer.

volunteer-wheat

 

This is an ideal situation for most wheat pests, i.e. Hessian flies, winter grain mites, wheat curl mite, and the wheat aphids (mainly greenbugs, bird cherry oat and English grain) as well as the pathogens they may vector.  Thus, please remember to destroy all volunteer at least 2 weeks prior to planting to help manage these pests.

Sorghum Pest Update

— by Dr. Jeff Whitworth, Dr. Holly Schwarting and J.R. Ewing

Much sorghum throughout north central Kansas is at least in the soft dough stage and thus has passed through the most susceptible stages for sorghum headworm infestations.  However, any sorghum yet to head out will still be susceptible to these headworms as there will still be at least one more generation.

All four aphids species, corn leaf, greenbugs, sugarcane, and yellow sugarcane, are still in every sorghum field we sampled throughout north central Kansas.  All populations seem to be increasing but there are relatively healthy populations of beneficials present as well.

SCAwLB

Sorghum Pests Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Double cropped sorghum may still have some ragworm feeding during the whorl stage (see photo).  In addition, there will probably be at least one more generation of headworms and thus later planted sorghum needs to be monitored for headworms between flowering and soft dough when it is vulnerable.  Also, continue monitoring for aphids as there still seems to be a pretty good mixture of greenbugs, corn leaf, yellow sugarcane, and sugarcane aphids.  Some of the fields treated for headworms have reduced numbers of beneficials so they may not be there in sufficient numbers to help control these aphids.  However, some of the fields sampled this week that were sprayed for headworms at least 2 weeks ago had pretty good populations of beneficials already building back up.

sorghum headwormsfall armyworm_sorghum

 

 

Sorghum Pest Update

— by Dr. Jeff Whitworth and Dr. Holly Schwarting

The situation seems about the same throughout north central Kansas with regard to insect pests.  Still finding mixed populations of aphids (greenbugs, corn leaf, yellow sugarcane, and sugarcane) but beneficial insect populations (mainly green lacewings, lady beetles, parasitic wasps, and occasionally syrphid fly larvae) still remain plentiful.  Headworms are also plentiful in just about every field that is not yet at soft dough.  Remember, expect 5% loss/worm/head between flowering and soft dough.  Chinch bugs, both adults and nymphs, are also plentiful at the base of most plants but can also be found feeding on young developing berries in the heads.

Sorghum Update

–by Jeff Whitworth and Holly Schwarting

Double cropped sorghum in north central KS seems to have a significant infestation of “ragworms”.  The larvae are a combination of fall armyworms and corn earworms and are of various sizes.

corn earworm_ragworm

windowpane ragwormfall armyworm_ragworm

 

Leaf feeding in the whorl by either species is highly visible but should not have a significant effect on the plants or yield.

windowpane ragworm

ragworm feeding

Also, most fields in north central KS are infested with aphids.  Corn leaf aphids can produce a great deal of honeydew but mostly in the whorls.  This honeydew may retard head extension but usually does not affect many plants over a large area.

corn leaf aphids

greenbugs

Yellow sugarcane aphids

Also found greenbugs and yellow sugarcane aphids.  None of the invasive sugarcane aphids were detected in north central Kansas.  However, many beneficials are, and will continue to be, present in sorghum fields as evidenced by the numerous green lacewing eggs and lady beetle eggs.

lacewing eggs

Volunteer Wheat

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Wheat harvest is completed, or at least real close, across the State. So, it is time to start thinking volunteer wheat control. As wheat producers know, volunteer wheat is very persistent. Every time it rains or the fields are irrigated, another flush or crop of volunteer wheat germinates. Thus, control needs to be just as persistent. Volunteer wheat can be a harborage for most wheat pests, especially bird cherry-oat aphids, Brown wheat mites, English grain aphids, greenbugs, Hessian flies, wheat curl mites, and many of the more common pathogens. Season-long control is always best, but rarely practical. So, volunteer wheat eradication at least 2 weeks prior to planting is the next best management practice.

 

Wheat Update

–Dr. Jeff Whitworth and Dr. Holly Schwarting

Last week wheat aphid populations were active and had increased considerably from the previous couple of weeks in north central Kansas.  Populations of bird cherry-oat aphids, English grain aphids, and greenbugs were all reproducing and still migrating in.  This week however, in fields we sampled in north central Kansas, the aphid populations had decreased drastically and the beneficials, especially lady beetles, had increased greatly.

Lady beetle larva 2

lady beetle adult

Last week these English grain aphids were inadvertently identified as greenbugs.

English grain aphids

Wheat Aphids

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Wheat aphids, primarily bird cherry-oat and greenbugs, continue to migrate into Kansas on southern winds.

GB adult and nymphs

BCOA nymphs

The most common question this last week then is whether to add insecticide to a fungicide application to kill the aphids.  First of all, we do not recommend pesticide applications unless justified, and the mere presence of aphids in wheat does not justify an insecticide application.  Aphids need to be at densities of 20+ aphids/tiller when wheat is in the boot to heading stages before aphids begin to impact wheat simply due to their feeding.  Even then, their feeding is more impactful on plants that are already stressed by less than ideal growing conditions and when there are few beneficials present, i.e. lady beetles, lacewings, parasitic wasps, etc.  Recent rains seem to have really helped alleviate the previous dry conditions- so growing conditions are not stressing the wheat.  When an insecticide is added to a justified fungicide application, the insecticide will kill the aphids, as well as all the beneficials.  The aphids will continue to migrate into the state but the beneficials will be gone and much slower to re-populate.  Foliar insecticide applications made to control aphids with the aim of reducing the transmission of Barley yellow dwarf viruses has not been proven and thus is not recommended.  At the present time there seem to be good populations of lady beetles and parasitic wasps in wheat fields to help mitigate aphid populations.

lady beetle larva

aphid mummy

Wheat Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Received a report from north central Kansas about a small wheat field infested with ca. 20 aphids/tiller, but the aphids weren’t identified.  All wheat fields we visited in the last week had aphids, including bird cherry-oat, English grain, and/or greenbugs.  However, we were only finding about 1/10 plants or less and beneficials (lady beetles, lacewings, and parasitic wasp activity) were present in all of these fields.  Most wheat averaged Feekes 6-8 and no other pests really have been noted.

Sorghum Pest Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Aphids are becoming easier to find in sorghum fields throughout south central and north central Kansas.  However, they are a mixture of greenbugs, corn leaf aphids, yellow sugarcane aphids and the new-to-Kansas sugarcane aphid.

aphid species

Probably the easiest way to find aphids is to look for the shiny/wet looking leaves and then examine the undersides of the leaves immediately above the ‘wet’ leaves.  This is the honeydew produced by a colony of aphids.

honeydew

 

Headworms are still very common throughout north central and south central Kansas.  There are all stages present, but remember the sorghum is vulnerable from flowering to soft dough.  These headworms may cause up to 5% loss/worm/head throughout the approximately two weeks that they are feeding directly on the grain.

sorghum headworm in berry

 

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