Sorghum Tips

For Texas High Plains, Headworms are Here, Complicating Sugarcane Aphid Control

This tip was provided by:

Calvin Trostle, Extension Agronomy, Lubbock, 806-746-6101, ctrostle@ag.tamu.edu

High Plains

For Texas High Plains, Headworms are Here, Complicating Sugarcane Aphid Control

As much as I would like to talk about something else in this Sorghum Tip, last week I cautioned High Plains growers to guard against complacency regarding sugarcane aphid.  If you are a sorghum grower downstate, bear with us we try to reduce the possibility of train wreck in some High Plains fields.  Any field that I have looked at that was treated with either Transform or Sivanto has had excellent control (to my knowledge almost all were by ground rig).  I have noticed, however, a higher than normal number of winged SCA in several fields.  These have to be watched as they can lead to colonies.  Furthermore, SCA counts in our AgriLife Lubbock Center SCA tolerance test was completed on Sept. 2, but I was back in the field on Sept. 6 and there was a 10-fold increase in the amount of honeydew in just five days.

So keep scouting sugarcane aphid in the High Plains… especially as AgriLife Extension entomologists are reporting significant numbers of headworms in some fields.  You may have fields where they were active down in the whorl; when those leaves unfurled they were a mess.  But as long as worms don’t feed deeply in the whorl and damage the developing head, this is only cosmetic.  Now the headworm complex is moving into the head and in numbers and worm size that is above threshold.  This is a combination of sorghum headworm (cotton bollworm on cotton, or corn earworm on corn) and fall army worm.

If these worms are present at or above threshold in your field it will potentially complicate SCA control.  This is because you may have to go to a pyrethroid and/or Lorsban to get control.  And though this can also reduce SCA, you are likely eliminating your beneficial insects that fight SCA (adult lady beetles and lady beetle larvae; green lacewings; and syrphid flies, which I learned this week some locals call hover flies, or even ‘hoover flies).  This could make SCA even worse.

For further information on control of SCA as well as headworms (and also sorghum midge, if present) read about the control strategies in the Aug. 26 & Sept. 1 newsletters from Texas A&M AgriLife entomology’s “Focus on Entomology” newsletter at http://focusonagriculture.blogspot.com/

Two further thoughts:  1) Some growers are report receiving advice to include Lorsban in their SCA sprays of Sivanto or Transform—DON’T DO IT!  You could make things worse; 2) I watched an airplane sprayer treat SCA in southwest Hale County Wednesday:  I cringed to see the drift, the inability to cover the ends of the field due to power lines, etc.  There is just no way the farmer will get uniform SCA control.  What I saw would increase my resolve to use a ground rig with high carrier volume to spray every possible acre that needs treatment.  If you are now faced with spraying for SCA if you can cover even some of your acres with a ground rig, I encourage you to do so.