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Tag: soft dough

Sorghum Update – ‘Ragworms’, ‘Headworms’, and Aphids

–by Dr. Jeff Whitworth and Dr. Holly Davis

Late planted sorghum is still causing considerable concern throughout north central Kansas as the leaves grow out of the whorl and are significantly ‘chewed up’ looking.  These ‘ragworms’, primarily corn earworms and fall armyworms but also a few cattail caterpillars, are still active in younger plants.

 

As these plants reach reproductive stages, i.e. flowering, there will be a high probability of having ‘headworms’ (corn earworms and fall armyworms) infesting the kernels.  Sorghum heads are the most vulnerable between flowering and soft dough.  There are currently significant infestations of these headworms throughout north central Kansas with worms in various stages of development.  Headworms cause approximately 5% loss per worm, per head.

 

There are large numbers of corn leaf aphids, greenbugs, and even a few yellow sugarcane aphids around north central Kansas.  The first report of a sugarcane aphid colony from Saline Co. was made on 16 August. These aphids are attracting, and providing food for, large numbers of beneficials which seem to be keeping aphids relatively well controlled.  Insecticide applications have not been needed for aphids. More information on sugarcane aphids in Kansas can be found at My Fields: https://www.myfields.info/pests/sugarcane-aphid

 

For more information regarding sorghum insect pest management please refer to the KSU 2018 Sorghum Insect Management Guide: https://www.bookstore.ksre.ksu.edu/pubs/mf742.pdf

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

–by Dr.  Jeff Whitworth and Dr. Holly Schwarting

Sorghum is in various stages of development around NC Kansas. The late planted, which seems to be just in the whorl stage- to soft dough, or even farther along. Corn earworms (often called sorghum headworms/soybean podworms etc., depending upon the crop infested) are causing significant infestations and therefore concern because of the highly visible whorl feeding and subsequent “ragged”-looking leaves as they expand from the whorl. This feeding probably will have no effect on yield, and by the time the damage is noticed the worms are mostly finished feeding anyway. Therefore, treatment is rarely justified. Feeding on the kernels however which is the marketable product is a different story. Sampling for head-feeding worms is really relatively easy. Just take a small white bucket, bend the head over into the bucket and vigorously shake it against the sides of the bucket which dislodges the larvae. Then count the worms and divide into the number of heads sampled.

Sorghum headworms_small

Rule of thumb: kernel-feeding larvae cause 5% loss/worm/head. Sorghum heads are most vulnerable from flowering to soft dough. These larvae are relatively susceptible to insecticides so efficacy is usually pretty good. However, these insecticides will reduce beneficial insect populations which can help later if any aphid populations develop.

Sorghum hedworm_single

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