–by Jeff Whitworth — Field Crop Entomology
Sorghum is really struggling across north and south-central Kansas, due to the hot dry conditions. Much is, or just has, started to head out and because of these hot /dry conditions we are seeing quite a lot of incomplete or nonuniform development, even within fields. This makes management decisions for “headworms” even more difficult– but fortunately, at least so far, “headworm” populations have not been much of a problem. Remember, sorghum is vulnerable to “headworm” feeding mainly between flowering and soft dough. We are continuing to see sorghum aphids (sugarcane aphids) migrate into Kansas, as EVERY field monitored in the last 7 days had various levels of infestation, from winged females just starting to produce nymphs (see fig. 1), to fields which have been infested for a week or two (see fig. 2), to a few fields that have substantial populations (see fig. 3 by Marvin Pipes). So far, beneficials seem to be helping to keep most of these aphid populations below treatment thresholds. However, monitoring should continue as these aphids will continue migrating into the state until the advent of much cooler weather.
Figure 1: Winged female sugarcane aphid + nymphs
Figure 2: Sugarcane aphid non-winged adults and nymphs
Figure 3: Substantial sugarcane aphid infestation