–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.
–Dr. Jeff Whitworth and Dr. Holly Schwarting
The first western corn rootworm adults were collected on 17 June from a corn field in north central Kansas. Development is being completed very quickly, which should be expected based upon the temperatures we have been experiencing. However, there are still some larvae feeding on roots.
None of the plants sampled have started tasseling and therefore adults are feeding on leaves. This typical leaf feeding by adults will not impact yield.
Adults will probably start feeding on emerging tassels and then shift to silk feeding when silks start emerging. Remember, corn plants are very efficient pollinators, so as long as a little silk is showing above the husk, the pollen will be successful. There are still many adult tarnished plant bugs in the corn fields and these are quite commonly confused with adult western corn rootworms. However, they will NOT clip silks.
Some leaf feeding is also evident by corn earworms and fall armyworms. Again, these leaves can look ragged, thus the name ragworm, but will not impact yield.