The early-planted corn fields should have been sprayed postemergence for later emerging weeds. In later planted fields, morningglories can be a challenge. Glyphosate is quite effective on small morningglories, but when they start to “run” or develop the vining growth habit, glyphosate is not as effective. If morningglories are an issue for your field, you should consider an additional 1.25 to 1.5 lbs of atrazine with your postemergence sprays in order to provide good residual control. However, this requires that applications be made before the corn is 12 inches tall. [Read more…]

Buggy-whipping in corn is a common sight early in the growing season and later under certain environmental conditions. The cause of buggy whipping is the abnormal formation of waxy leaf layers causing leaves to unfurl improperly. Agrichemicals and environment can cause this. [Read more…]

There have been many situations where both fomesafen (active ingredient in Reflex) and glyphosate will complement each other for weed control. Syngenta has a premix of fomesafen plus glyphosate called Flexstar GT. Also, Reflex and glyphosate can be tankmixed, but there have been some situations of these two products not mixing well. The following is an article from Ken Smith from University of Arkansas entitled “Problem Solving Incompatible Tankmixes of Glyphosate and Reflex®”

Some growers have experienced cottage cheese spray mixtures when Reflex® and glyphosate were tankmixed in an effort to burn down existing weeds while applying Reflex® prior to cotton or soybean planting.

If a mistake is made and Reflex® and the potassium salt of glyphosate is mixed and found to be incompatible, it can likely be brought back into solution by adding household ammonia. Start with 1% ammonia and begin agitation. More ammonia may be added if needed.

I have observed a lot of emerged Palmer amaranth seedlings.

Early planted corn should be scouted at 4 weeks after planting to determine if a POST herbicide application is needed. A lot of no-till soybean fields need a burndown herbicide, and if Palmer amaranth is present in those fields, it makes things challenging. If the field was burned down earlier, and weeds have emerged since application, consider using Gramoxone (paraquat) to control emerged Palmer amaranth plants. Residual herbicides containing metribuzin or chlorimuron (unless the field has had history of poor control with ALS herbicides [Group 2]) will provide the greatest amount of help for burndown control of emerged Palmer amaranth in no-till soybean fields.

Available from the UD-REC website are weed management guides for assistance in weed control in corn, soybeans, or forages.
http://extension.udel.edu/ag/weed-science/weed-management-guides/

There is a separate guide for each commodity. The first half of the corn and soybean guides deal with soil-applied herbicides and the second half is for postemergence herbicides. These guides have pre-mixes and what is in the pre-mix, expanded weed control tables, information on application timing, comments for each of the herbicides, and much more. The forage guides cover alfalfa as well as grass forages.

Working with the Delaware Soybean Board and the United Soybean Board, a herbicide classification chart is available at:
http://extension.udel.edu/ag/weed-science/weed-management-guides/

This chart groups herbicides by mode of action and site group numbers that are printed on containers and labels. The chart is designed to help diversify herbicide use by rotating effective herbicides with different sites of action to delay the development of herbicide resistance. The chart provides the number of resistant weed species in the US to each site of action, which highlight those herbicides for which we already have wide-spread resistance.