Kansas State University

search

Extension Entomology

Tag: north central

Alfalfa Update – Alfalfa caterpillars and Potato leafhoppers

Posted on by Sharon Schroll

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Alfalfa caterpillars are currently active throughout north central Kansas.  These caterpillars are feeding on foliage, and based upon the size of the larvae in fields, will soon be pupating.  In many fields, swathing is currently, or has just been done and this should help lessen alfalfa caterpillar populations.  However, if the timing is such that these larvae are pupating in the soil and thus swathing does not remove/destroy the pupae, the emerging butterflies may lay eggs on recently cut fields and the developing larvae may feed on regrowth.  This may retard regrowth for a couple of weeks until larvae pupate.

Potato leafhoppers are also very numerous throughout north central Kansas in uncut alfalfa fields.  Thus, their characteristic feeding damage, called ‘hopper burn’, is common.  Swathing should reduce potato leafhopper populations significantly and, hopefully, they will not rebound.  Continued monitoring is prudent as alfalfa caterpillar feeding and potato leafhopper damage may lessen the plant’s ability to store reserves in their roots for overwintering.

 

For management decisions for all alfalfa pests, please refer to the 2017 Alfalfa Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/MF809.pdf

 

Corn Update

Posted on by Sharon Schroll

By — Dr. Jeff Whitworth, Dr. Holly Schwarting

Most corn has been planted in SC and NC Kansas, although some has been struggling somewhat with the cooler temperatures, wet soils, etc.  Whatever the case, please remember insecticide seed treatments do a good job of protecting the seed and germinating plants, but not forever.  About 3-4 weeks of protection from the time of planting can be expected but after that, wireworms, white grubs, etc. may affect the seedlings, especially under less than ideal growing conditions.

Wheat Update

Posted on by Sharon Schroll

By — Dr. Jeff Whitworth, Dr. Holly Schwarting

Wheat fields sampled in NC Kansas over the last week have diminishing populations of aphids.  Many fields had to be sampled relatively vigorously to find any aphids.  However, lady beetles are still quite plentiful which should bode well for not allowing the aphid populations to rebound.

Scattered white heads are starting to be easily distinguished in the green wheat.  If the stem pulls out easily, with some apparent feeding in the stem, this is from the wheat stem maggot.

wheat stem maggot

The number of infested stems in always negligible relative to yield loss but often causes concern because of the easily noticed white heads.

Alfalfa Weevil Update

Posted on by Sharon Schroll

–by Dr. Jeff Whitworth and Dr. Holly Schwarting

Alfalfa weevils are still very active throughout north central Kansas.  They also range in development from small 1st instar larvae to relatively mature 3rd instars.

Aw life stages

We have also had reports of pupae in south central and north central Kansas.  Many fields are still showing signs of freeze damage.

freeze damaged field

The freeze did seem to affect the weevils by slowing their development but did not kill them.  However, most larvae in freeze-damaged fields are more yellow than the usual greenish color.  Whether that means they are getting the proper nourishment from the yellowed, freeze-damaged alfalfa tissue or not is unknown.

larvae color difference

Weevil larvae in untreated, non-freeze-damaged fields seem mostly about to pupate within 7-10 days if temperatures stay between 45-80°F.  No other pests have been noted in alfalfa fields we visited over the past week.

Wheat – Aphids

Posted on by kansasbugs

—by Dr. Jeff Whitworth and Dr. Holly Schwarting

Aphids, mainly bird cherry oat and greenbugs continue to migrate into wheat fields throughout north central and south central KS (see photos). When temperatures are warmer and winds are from the south, these aphids are migrating/blowing in, in significant numbers. However, we did note some mummies (parasitized aphids) in these fields so these little wasps are active and will probably help control these pests if insecticides are not used in these fields.

difference between aphid species