Posted on Aug 12, 2020
By Brent Bean, Ph.D., Sorghum Checkoff Agronomy Director
The sorghum crop in the High Plains is progressing nicely. Although there are exceptions, timely rains have improved the outlook for good yields throughout most of the region. August is typically the month for insect issues, but so far these have been minimal.
Sugarcane aphids have been found in a few counties. The furthest north that I am aware of is a small colony of SCA found in a field a few miles northwest of Great Bend, Kansas, discovered a few days ago. Interestingly, this year it seems SCA are showing up in fields that are miles apart rather than gradually migrating north. I am aware of only a couple of fields in the Texas Panhandle that have been sprayed. On the whole, most fields are SCA free or occasionally found at low numbers.
There has been some confusion this year between the corn leaf aphid and SCA. Below are pictures of corn leaf aphid. They can appear in great numbers on a sorghum plant, usually in clusters in a field. They are almost always found in the whorl of the sorghum plant. They are a dark green color with an almost black head and cornicles (tail pipes) and black legs. In contrast, the SCA is more of a yellow color, but does have black tipped legs or black cornicles. The SCA will be found on the bottom side of leaves rather than in the whorl. The confusion comes from the fact that both can produce a lot of honey dew.
Corn leaf aphids are generally considered a good thing because they provide a food source for beneficials that will be needed if SCA infestations occur in the field. There is no established threshold for corn leaf aphid. After talking to several extension and research entomologists, no one had ever recommended spraying for corn leaf aphid.
Headworms also can be found in a few fields, but are in very low numbers so far. For headworm control, I want to mention that Prevathon has now been approved for banded application in KS, OK, TX, CO, NE, NM, SD and AZ. For those that can apply insecticide with ground rig, this offers the potential for significant savings.
Written August 10, 2020