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Extension Entomology

Tag: ovipositing

Sunflower Update – Gray and Red Seed Weevils

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Double-cropped sunflowers are highly susceptible to both gray and red sunflower seed weevils.  Most double-cropped sunflowers sampled in the past week, just reaching the bud stage, were significantly infested with both seed weevils, i.e. more than two of each species/plant.

 

 

 

These weevils are, and will be ovipositing and the small grub-like larvae will consume or otherwise destroy the seed.  This damage can significantly reduce yield if enough seeds are destroyed.  For more information on sunflower insect pest management, please refer to the KSU Sunflower Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/mf814.pdf

 

 

Chinch Bugs

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

 

Chinch bugs are numerous and very active throughout north central Kansas, and have been for at least the last month.  The overwintering adults deposited eggs in wheat and oats, as far as our agricultural crops are concerned, and apparently the overwintering survival was relatively high because there have been huge numbers of chinch bugs migrating from these two crops.  Fortunately, most of the corn and sorghum have developed enough to be able to withstand relatively large numbers of chinch bugs as they suck plant nutrients.  Chinch bug populations sampled this past week consisted of 90% nymphs (both the very small reddish orange and larger gray nymphs, both of which have a transverse white stripe).

 

 

These nymphs, for the most part, are around the base of the plants feeding behind the leaf sheaths.  These bugs will feed and develop for approximately another couple of weeks, then mature into adults.  Mating and oviposition then will start another generation of chinch bugs that will continue to feed in corn and/or sorghum fields.  With good growing conditions, most of this feeding will go unnoticed and have little effect on yield.  However, if growing conditions deteriorate but bugs continue feeding, they can cause stalk lodging, which makes harvesting much more difficult.  Spraying for chinch bugs at this stage of crop development is usually not effective as most bugs are relatively inaccessible to insecticides at ground level behind leaf sheaths.

 

Soybean Pest Update

— by Dr. Jeff Whitworth and Dr. Holly Schwarting

Green Cloverworms in Soybeans

Remember a few weeks ago when there was considerable concern relative to all the green cloverworms causing irregular holes in leaves? Even skeletonizing some areas of some fields until treated with an insecticide and/or and entomopathogenic fungus started decimating the larval populations?   Well, the surviving larvae pupated and now are annoying little aerodynamically shaped dark brown moths flying around lights at night or trying to get in through doors and windows.

gcw-close

gcw-defol

gcw-fungus

gcw-adult

These moths will mate and then begin ovipositing in soybean and/or alfalfa fields.  Eggs hatch in approximately 10-14 days and the larvae will again start feeding on leaves of either crop.  By this time of year, the larval feeding is usually of little consequence relative to yield.  However, really late planted soybeans, and all alfalfa fields, should be closely monitored to ensure leaf feeding in either crop does not affect pod fill in soybeans or leaf area in alfalfa.

 

Soybean Podworms

These insect pests seem to be on about the same developmental schedule as green cloverworms.  So, late planted soybeans may be at risk for bean feeding within the pods.

cew-adult

cew-pod-damage

 

Adult bean leaf beetles, while probably not as numerous as in past years, may still be feeding on the pods themselves.  This can cause yield reductions.  For more information on bean leaf beetle biology and control, please visit: https://www.bookstore.ksre.ksu.edu/pubs/MF2824.pdf

blb-adult

blb-feeding-pod

Woollybear Larvae

Another leaf feeder that can cause concern this time of year is woollybear caterpillars.  There are several different species but all are foliage feeders although they rarely cause any economic problems.

woollybear-white

woollybear-orange

 

Stink Bugs

Hopefully, most soybeans are past the stages that are succulent enough for stink bugs to be feeding on.  However, there are still some late planted beans setting pods with seeds that may be vulnerable to stink bug feeding.  So, until pods are turning yellow or brown, fields probably should continue to be monitored for soybean podworms, adult bean leaf beetles, and stink bugs.

green-stink-bug

Soybean Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

We are still not finding any pests at threatening levels in soybeans, yet.  Dectes stem borer adults are actively ovipositing in petioles and larvae are/will be hatching and tunneling into stems for the next 4-6 weeks.  For more information please see the KSRE publication Dectes Stem Borer: https://www.bookstore.ksre.ksu.edu/pubs/MF2581.pdf.

Dectes

There has been some concern about white flies in soybeans.  They do seem to be plentiful but they will not cause any problems relative to yield.

 

whitefly soybean

white fly close

Sorghum Pest Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

The majority of the double cropped sorghum seems to be past flowering and almost to the soft dough stage.  This means much of this crop is almost past the susceptible stage relative to corn earworms (a.k.a. sorghum headworms), which is about soft dough.  Later planted sorghum still needs to be monitored though as earworm moths are still ovipositing in sorghum heads.  Sugarcane aphids (SCA) are still very active in north central Kansas, as are their natural enemies, and thus these populations should also continue to be monitored.  The insecticides registered for sugarcane aphids have performed really well at controlling these aphids, as have the products used for controlling headworms.  Just remember, gallonage is extremely important for SCA applications.

Blister Beetles

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Blister beetles are aggregating in many different fields throughout north central Kansas. These swarms are causing much concern.  Blister beetles can be controlled, if needed, however they usually do not cause widespread defoliation field-wide.  They normally aggregate in large numbers in localized areas for a week to 10 days.  These swarms can occur in soybean fields (see photo), alfalfa fields, and/or on pigweeds adjacent to these fields (see photo).  These swarms will soon disperse so the females can start ovipositing and thus will not cause as much concern in crop fields.

blister beetle soybeans

 

blister beetle pigweed

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