Glory Herbicide (metribuzin) Receives Special Local Need Label for Control of ALS-Resistant Chickweed in Pennsylvania
Posted: March 5, 2013
The manufacturers of Glory Herbicide (Makhteshim Agan of North America, Inc.) which contains 75% metribuzin have received a FIFRA 24 (c) Special Local Need label for control of ALS-resistant chickweed in winter wheat and winter barely in Pennsylvania. This herbicide is not currently labeled for wheat and barley in other Mid-Atlantic states, but is labeled in Ohio and some states to the West. Other brands of metribuzin do not have this special use in Pennsylvania. Specifically, Glory should be applied to winter wheat or barley at 2 to 4 oz/acre after the crop is beyond the 3-tiller stage but before jointing. This is a relatively low rate of metribuzin that is specifically targeting chickweed but it will also suppress other winter annual broadleaves. We are not labeling above the 4 oz rate because there is some concern for crop injury and especially at higher rates. In our trails last year, 2 to 4 oz/acre applied in the spring did an excellent job controlling common chickweed; metribuzin alone or in combination provided greater than 90% chickweed control. In general, fall-applied herbicide generally provided more consistent control of common chickweed, but spring metribuzin treatments were adequate as well. For best results, apply metribuzin when chickweed is small (4-6 inches in diameter). Glory can be tank-mixed with other herbicides such as Harmony Extra, 2,4-D, and Banvel to broaden the spectrum of control. We have not tested combining Glory with fluid fertilizer, but this would certainly increase the potential for crop injury, especially if a surfactant is also added. Some wheat and barley varieties are known to be sensitive to metribuzin and a list of known tolerant varieties is provided on the Glory label. You can find the Glory 24 (c) label at CDMS.net.
Starane (fluroxypyr) is also labeled for wheat and barley and is another herbicide that has provided control of ALS-resistant chickweed in Penn State trials. Starane will generally need to be tank-mixed with Harmony Extra or a similar product to broaden the spectrum of control. Currently, the ALS-resistant chickweed populations are not yet widespread in Pennsylvania and primarily located in southeastern Pennsylvania, but have been documented in neighboring states to the south, so keep a watch for this problem in your area. Crop rotation and the use of other weed control tactics including different herbicide programs and modes of action provides the most reliable means of controlling ALS-resistant common chickweed. As we learn more about this problem and about other management tactics for this weed, we will keep you posted.