–by Dr. Jeff Whitworth and Dr. Holly Schwarting
Just another reminder that all volunteer wheat (and there seems to plenty around north central Kansas) should be destroyed at least 2 weeks prior to germination of the planted wheat to mitigate infestation/infection by insects, mites, and/or pathogens.
–by Dr. Jeff Whitworth and Dr. Holly Schwarting
Please remember the absolute best way to help mitigate most wheat pests, including insects, mites, and pathogens is to control all volunteer wheat. Volunteer wheat, at the very least, should be killed at least two weeks prior to the planted crop germination.
–by Dr. Jeff Whitworth and Dr. Holly Schwarting
An update on a Hessian fly infested wheat field. Last winter, Mr. Arlan Newby, a consultant in southeast Kansas, discovered a wheat field that had a significant Hessian fly infestation (photos 1 & 2), to the point where many of the plants were actually killed or weakened enough that they were not able to withstand any other stress. Most of the field was therefore plowed under to allow for planting a spring crop. However, a small portion was allowed to remain so we could determine the Hessian flies’ impact in spring (photo 3) and just prior to harvest (photo 4). As seen in these photos, it was apparent that many plants survived into spring and actually looked as though they may tiller out sufficiently to compensate for the Hessian fly infestation. However, as seen in this most recent photo, the remaining plant stand was significantly reduced and there is already considerable lodging. This entire field could have ended up like this little corner if it were not for the keen observations of Mr. Newby. This situation serves as a reminder for how devastating this wheat pest can be. For more information on the biology and management of Hessian fly, please visit: http://www.ksre.ksu.edu/bookstore/pubs/MF2866.pdf
–Dr. Jeff Whitworth and Dr. Holly Schwarting
Corn
Plants in north central and south central parts of the state are finally starting to grow. All the cloudy, wet conditions have not been the best for corn development and many fields are a little more chlorotic looking than usual for this time of year. This stalled development usually allows pests more time to feed and thus cause damage. Seed treatments only provide protection for 3 to 4 weeks (check label) from planting, so most of that protection has dissipated. However, we have not seen nor heard about much pest activity yet. A few thin stands have been noted which can be caused by many different pests, probably most common so far has been wireworms. Generally, however, most fields are past seedling damage.
We have received a few calls about armyworm activity in wheat and sorghum, so when these larvae pupate and then emerge as adults to lay eggs, most corn will be in the whorl stage so there may be some whorl-stage leaf feeding which is always highly visible but causes very little actual impact on yield.
Wheat
We have not seen any “worms” in wheat, but have received several calls about armyworms feeding on leaf tissue. Armyworms should move to another grass host, i.e. corn, sorghum, brome, etc. as the wheat begins to senesce. They actually devour leaf tissue and thus are not actually feeding on the grain.
If there are thin, light green or tan worms feeding on the wheat head they are probably wheat head armyworms (see photo). They can and will actually feed on the grain whereas the armyworm feeds on the foliage around the grain – not the grain itself.
If you decide to treat either pest, please refer to the Wheat Insect Management Guide, 2015: http://www.ksre.ksu.edu/bookstore/pubs/MF745.pdf and make sure to check the label for the preharvest interval (PHI) if spraying wheat this close to harvest.
—by Dr. Jeff Whitworth – Dr. Holly Schwarting – J.R. Ewing and Salehe Abbar & Dr. Brian McCornack
Wheat aphids, primarily greenbugs, but bird cherry oat and English grain aphids as well, continue to migrate into wheat fields all over the state. However, there are increasing numbers of lady beetles and parasitic wasps (see photo of mummy). Hopefully these beneficials will keep these aphids well below treatment thresholds.
More information about greenbug identification, current management recommendations, or their natural enemies can be found on the myFields.info website (www.myfields.info).
—by Dr. Jeff Whitworth and Dr. Holly Schwarting
Aphids, mainly bird cherry oat and greenbugs continue to migrate into wheat fields throughout north central and south central KS (see photos). When temperatures are warmer and winds are from the south, these aphids are migrating/blowing in, in significant numbers. However, we did note some mummies (parasitized aphids) in these fields so these little wasps are active and will probably help control these pests if insecticides are not used in these fields.
