University of Georgia
Extension Peanut Agronomist
Successful weed management depends upon starting off on the right foot. First, it is essential that a grass herbicide (a pendimethalin product, e.g. Prowl, or an ethalfluralin product, e.g. Sonalan), be used pre-plant incorporated (PPI) or pre-emergence. According to weed scientists, a grass herbicide applied PPI or pre-emerge is the backbone of a herbicide-based weed management program. The second critical factor is to keep fields weed free for the first six weeks of the season. Weeds that emerge after six weeks are not as competitive for water and nutrients. However, letting weeds that emerge after six weeks go uncontrolled could result in those weeds interfering with fungicide applications or with harvest. The third critical factor is to control weeds when they are two inches or shorter. Weeds allowed to exceed two inches in height are much more difficult and costly to control.
Texas A&M University
The most important thing in the first month of a peanut crop is weed control. This early period is when the crop is most susceptible to competition from weeds. Yield loss is at a premium. Control any weeds that escape preplant or pre-emergence programs. There are many good herbicide options for weed control in peanut. Know what weeds you are trying to control and which herbicides control that weed spectrum. Tailor each postemergence herbicide program to the individual field to achieve the most success. You may need to combine herbicides to get the most effective control of all weeds in a particular field. In addition, consider rotation crops to make sure the herbicides fit the overall cropping system. “Weeds of the South,” an excellent resource for helping identify weeds properly, is available through UGA Press and other outlets.
North Carolina State University
As we move into May, there are many key decisions that have to be made quickly. Early season scouting and paying attention to small details can pay major dividends as we move through the season (in the V-C, our growing season is squeezed.) Applying Orthene early postemergence in a timely manner is critical if in-furrow products are ineffective. If you plan to use paraquat, this needs to be applied within the first three weeks after emergence to avoid excessive injury and challenges in peanut recovery. If you have significant thrips damage, go easy on the paraquat as we often see yield reductions with the combination of thrips damage and paraquat injury, irrespective of variety. Avoid letting weed escapes get past you. Yes, it often seems as though we are spending a great deal of money upfront, but trying to clean up pigweed and other broadleaves for the remainder of the season can be just as costly and, in many cases, unsuccessful.
Producers often wonder if paraquat decreases yield potential. Research has shown no yield decrease when using paraquat for early season weed control. However, there are factors to consider, “Do I have any Florida Beggarweed, and are there any small grass escapes from the yellow herbicides?” Having Florida Beggarweed early in the season is the reason I suggest paraquat. If you do not to attack this weed early, after seeing the escapes, you miss a good opportunity to kill it very economically. Also, choosing not to kill beggarweed at this time forces you to wait to until 60 days after emergence to use Classic. This is a lot of time to deal with the weed and increase chances of TSWV from the use of Classic. Remember, you not only get the beggarweed but also the small grass escapes, which are very costly to get later.