Fall weed control can give the best weed control but it also can be a poor time. If the noxious weeds were sprayed or clipped earlier this summer and there is good weed growth now, this would be a good time to spray these weeds and get a good kill.
We have received several reports of spider mites showing up in corn throughout South Dakota. The two species of spider mites that may be present in corn are the two-spotted spider mite and the banks grass mite.
Two corn samples submitted to the South Dakota State University Plant Diagnostic Clinic from Turner County were confirmed to have bacterial leaf streak. This is the first report of this disease in South Dakota in 2017.
While scouting corn the last few weeks, we have been noticing several fields containing small populations of aphids. At this point in the season, such aphid populations do not pose a threat to yield. However, this presents an opportunity to discuss when to worry about aphids in corn.
Since corn silage harvest has started to occur throughout the state we have been receiving a lot of questions regarding corn smut and whether or not it is a concern if fed to livestock. Common corn smut is considered a minor disease of economic importance in South Dakota.
Utilizing sound research results to help make decisions on the farm is a wise business practice. It can be confusing, however, when you see two numbers that are clearly not the same labeled as “not significantly different.”
It is close to three years now since the first palmer amaranth (Amaranthus palmeri) was found in South Dakota. Since that time there are about a dozen confirmed sites in the state. Now is the time of year to be looking for palmer.
Southern rust was confirmed in Turner, Union, Lincoln, Minnehaha, and Brookings Counties last week. It is most likely that at this time this rust is wide spread in other counties not yet scouted. Southern rust develops under warm and wet weather which is the reason it is considered a late season disease in South Dakota.
Brome mosaic disease was found in one corn field in Brookings County with just a few plants in the head-rows showing infection. Infected plants were stunted and had chlorotic streaks parallel to the veins.
Cool temperatures over the last couple of weeks have brought a slow down to growing degree day (GDD) accumulation for corn. Up until early August, GDDs for corn were accumulating at approximately the average rate.