Weeds and Herbicide Application
Bluegrass (aka Poa) and broadleaf winter annuals like henbit have caused serious yield loss in some wheat fields the last several years. In cases where these weeds were a problem, they became established before or with the wheat. If Poa or henbit becomes established with the wheat, it can deter tillering and readily compete for nitrogen. One way to manage these weeds is to apply Sencor at 3 to 4 oz/a postemergence over the wheat that is at 2 to 41f. This timing of a Sencor application has been a very inexpensive way to manage bluegrass and broadleaf weeds like henbit. Unfortunately, through the years, some wheat varieties have been prone to injury from a Sencor application. The Sencor label contains a list of sensitive wheat varieties. However, it is dated and not one variety on the current Sencor label is grown in Tennessee. More worrisome is that no wheat variety currently grown has been tested for sensitivity to Sencor by the seed companies. As a result, over the past two years we went to the county wheat trials and sprayed a 10-foot boom width of 4 and 16 oz/A Sencor across the back side. We then rated the varieties in the test for tolerance to Sencor. This work was conducted in Tennessee and Arkansas.
The Sencor tolerance ratings are listed as T = tolerant, MT = moderately tolerant, MS = moderately susceptible and S = susceptible. The next column on the chart lists the number of observations. The more number of observations, the more confident a producer should be in the rating. Varieties that have less than four observations should be read with caution. In general, varieties listed with a T or MT have shown good tolerance to Sencor. Growers should be cautious about using Sencor on varieties rated with a MS grown on coarse soil types. Wheat growers should avoid using Sencor on varieties rated S for Sencor tolerance.
"W213 Sencor™ Tolerance Ratings for Selected Wheat Varieties," The University of Tennessee Agricultural Extension Service, 09-0164 W213, http://trace.tennessee.edu/utk_agexcrop/116