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Extension Entomology

Month: September 2015

Soybean Pest Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Soybean pests, in general, remain relatively sparse.  There are a few green cloverworms and stink bugs, but apparently not in overwhelming numbers.  Many double cropped soybeans are in the most susceptible reproductive stages, so any pests that quickly increase in numbers may cause some yield reductions and therefore these fields need to continue to be monitored.

Sugarcane Aphids

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Sugarcane aphids are also still causing much concern throughout KS.  Dr. Bob Bowling, Extension Entomologist TAMU, has conducted research on these aphids for a couple of years in Texas and answered a couple of the most common questions about this aphid.  According to Dr. Bowling, these aphids will not infest corn or wheat, only plants in the sorghum family, i.e., sorghum, Johnsongrass, shattercane, etc.  They are a tropical or sub-tropical insect so probably will not overwinter in KS, or even continue to thrive and increase in numbers as the weather becomes cooler with lower humidity.  Also, and maybe most importantly, the honeydew breaks down within a few days after the colony is gone (or at least is no longer producing honeydew).  The products registered in Kansas for treating these aphids (Transform and Sivanto) both seemed to provide good control in the TAMU efficacy trials when used with at least 15 gal./acre of water (carrier).

sugarcane aphid colony

Chinch Bugs

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Chinch bug populations continue to cause concern in north central and south central Kansas.  Occasionally, in past years when rainfall was plentiful and humidity high, chinch bugs were controlled by an entomophagous fungus.  However, this always occurred during the ‘walking migration’, when the nymphs were aggregating in wheat and started moving out as the wheat senesced, to feed on nearby seedling sorghum and/or corn if adjacent to wheat.  The chinch bugs are now more dispersed around sorghum fields and therefore the fungus may infect a few bugs but will probably not help control these populations which are increasing and therefore need to be monitored.  For more information on chinch bug biology in Kansas, please visit: http://www.bookstore.ksre.ksu.edu/pubs/MF3107.pdf

Volunteer Wheat

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Please remember the absolute best way to help mitigate most wheat pests, including insects, mites, and pathogens is to control all volunteer wheat.  Volunteer wheat, at the very least, should be killed at least two weeks prior to the planted crop germination.

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

 

Soybean Pest Update

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Soybean aphids are still relatively common throughout north central Kansas.  Their numbers don’t seem to be increasing but they are easy to find in most fields. Thus, please be vigilant as these are aphids and populations can increase quickly under the right conditions.

Numerous defoliators are present in soybeans including green cloverworms, soybean loopers, a few bean leaf beetle adults, a few soybean podworms (corn earworms), the occasional thistle caterpillar, and some grasshoppers (see pics).

soybean defoliators

Sorghum headworms…plus sugarcane aphid – What to do?

–by J.P. Michaud

With sustained southerly winds continuing for the next 4-5 days, sugarcane aphids (SCA) are moving north. New detections this week include Barton, Ellsworth and Riley counties, with other in-between counties likely infested and only awaiting detection. Given the heavy populations of headworms this year (fall armyworm and corn earworm), I have been getting questions about how best to obtain control of both pests simultaneously. A lot of these worms are getting too big to treat and will pupate soon, so do not consider treatment if a majority (>50%) are more than 1.0-1.25 inches long.

Products of choice for SCA control are Transform® (sulfoxaflor, Dow Agro.) and Sivanto® (flupyradifurone, Bayer) that block aphid feeding and have good absorption into leaves (translaminar activity). However they will not control the headworms.

SCApanicle

Sugarcane aphids moving from flag leaves into panicles

Products of choice for headworms are diamides such as Prevathon® (chlorantraniliprole, Dupont) and Belt® (flubendiamide, Bayer). They provide excellent control of caterpillars and require consumption by the insect to be activated, so they tend to be more selective for beneficial insects and pollinators. Labels on all these products contain instructions indicating their general compatibility with other products in tank mixes.

This morning I mixed up a blend of Transform and Prevathon in 200 ml of water and it seemed to form a nice ‘milk’ – I did not see any adverse reactions such as formation of a precipitate. The Transform is a wettable granule formulation, so add the granules first and agitate well before adding an emulsifiable concentrate or other liquid formulation. It is always a good idea to check a small mix in a jar first if you haven’t combined particular products before.   Finally, I recommend avoiding the use of all pyrethroid materials in sorghum because of their potential to kill of beneficials and make the aphid problems even worse.

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