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Extension Entomology

Month: July 2016

Sorghum Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Chinch bugs are really common in sorghum fields throughout north central Kansas.  Their feeding will weaken stalks if dry conditions are prevalent.

Green lacewing eggs were present, indicating the presence of future beneficials to help with control of potential future aphid populations.

lacewing egg

chinch bug nymps2

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

Alfalfa Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Swathing seems to have interrupted the potato leafhopper increases that were seen prior to cutting.  All the fields sampled prior to swathing in north central Kansas exceeded the treatment thresholds.  Conversely, all the fields sampled post-swathing had potato leafhopper population well below economic injury levels, i.e. 20 potato leafhoppers per 20 sweeps pre-swathing vs. two per 20 sweeps post-swathing.  Continued monitoring would be prudent as these pests may stray around until October and continue to produce offspring.

 

Spotted alfalfa aphids are still present in alfalfa fields but at relatively insignificant infestation levels.  These aphids seem to do very well in mid-summer’s hot, dry conditions but usually don’t reach densities heavy enough to cause yield-reducing stress.

spotted alfalfa aphid

Alfalfa Pests

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Fields sampled three weeks ago had relatively large numbers of potato leafhoppers, i.e. 20+/20 sweeps.  These fields were swathed approximately two weeks ago and averaged 2 potato leafhoppers/20 sweeps, below the treatment threshold. Thus, timely swathing can be very beneficial in managing potato leafhoppers, without use of an insecticide application.

 

Corn Pests

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Most corn pests have come and gone throughout north central and south central Kansas, with a few exceptions.  Japanese beetle adults have been causing concern in north eastern KS, from about Topeka to the Nebraska border and east to the Missouri border.

Japanese Beetle

Green june beetle

 

These beetles are attracted to green silks and can feed so voraciously that they eat into the husks and damage some of the kernels on the tip.  These populations usually do not occur in such numbers to affect pollination over a large area of many fields.  However, in small areas they can cause concern but are relatively well controlled if a foliar insecticide is justified.  Some adult green June beetles are also feeding on corn silks and/or ‘naked ears’ and have been mistaken for Japanese beetles.  Japanese beetles usually migrate to soybean fields to feed on pollen when fields start pollinating but probably not to the extent that they affect yield.

 

First report of sugarcane aphid in Kansas sorghum for 2016

—by the KSRE Field Crop Extension Entomology Team

Our team has been actively scouting sorghum fields the past few weeks for any infestations of sugarcane aphid, which is a relatively new pest affecting Kansas sorghum. We received a report from Jill Zimmerman (KSRE Extension Agent, Cowley County, KS) on July 18, 2016 of a potential infestation in a commercial field near the Sumner/Cowley County border; the report was confirmed in two fields this morning by a state specialist. Based on the size of the aphid populations observed, which included several plants that were producing winged aphids (i.e., alates), this field was first infested approximately 3-4 weeks ago. A significant number of natural enemies were observed feeding on aphids, which can help to slow aphid growth.

Photo Jul 19, 12 53 01 PM

Sugarcane aphid populations have been slow to build in Texas and Oklahoma this growing season. This record is approximately 10 days sooner than when we found aphids in 2015. Aphid densities are well below threshold, but those with sorghum fields are encouraged to scout fields now.

Photo Jul 19, 11 41 42 AM

Report all new infestations by contacting your county extension agent. For myFields.info users, submit reports using the Pest Sampler module (https://www.myfields.info/pest_sampler). To receive pest alerts about sugarcane aphid, create an account (https://www.myfields.info/user/register) and include your state and county information to receive notifications specific to your area.

For more information on sampling procedures, action thresholds, or effective insecticides, visit https://www.myfields.info/sca.

Scout early, scout often, and know before you spray.

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