JOHN P. BEASLEY, JR.
University of Georgia
Extension Peanut Agronomist
Research clearly indicates weed management is most critical the first six weeks after planting. If a field is kept relatively weed free the first six weeks after planting, weeds that emerge after that time are not as likely to cause a yield reduction. However, weeds emerging after the six-week period following planting can create significant problems by interfering with harvest.
The second factor in effective weed management is controlling weeds before they exceed two inches in height. It doesn’t take long for most weed species to exceed two inches in height. During planting season, it is easy to get caught up with activities and forget to follow up on the first-planted fields. Weeds in those fields can quickly get out of control. Always use a grass herbicide at planting and identify emerging weed species in order to select the most cost-effective herbicide or herbicide combinations.
Texas A&M University
Selecting herbicides and planning a program that will control weeds so peanut yield is not affected and weeds do not cause problems with harvest are important considerations. Select a herbicide program that works in rotational crops and rotates herbicide chemistries and classes in those crops to reduce the potential for weed resistance.
Another factor is herbicide timing. Generally speaking, smaller weeds are easier to control. Often, weather is more favorable and weeds are actively growing, which will ensure that herbicides perform as expected. Consult the label for weeds controlled, weed size and information on additives needed. “Weeds of the South” and/or “Weeds of the Midwestern United States and Central Canada” are excellent resources for identifying weeds and are available through UGA Press and other outlets.
North Carolina State University
Temik’s value for thrips control and nematode suppression is well documented. Options for nematodes are challenging, considering issues associated with fumigation. For thrips, Thimet/Phorate or Orthene in the seed furrow are good alternatives. However, the consistency of performance is often lower than Temik. Be prepared for early season applications of Orthene based on thresholds. Although two applications – in-furrow and postemergence – seem difficult, the cost is no more than one application of Temik. What about injury to peanut from Thimet/Phorate on sandy soils with low organic matter? While the damage is transient, it does look different compared to Temik.
Compatibility of Orthene, an inoculant and Proline has come up. The data indicate these products will work with no major problems, although more data is needed. Growers will have to adopt new approaches in managing thrips.
One of the biggest challenges facing producers today is Palmer amaranth (pigweed). This weed is hard to control not only in cotton, because of its resistance to glyphosate, but also in peanut due to the fact that it grows so fast and furious. It is extremely difficult to get rid of pigweed if you allow it to seed out because it leaves behind thousands of seed. Producers should use a residual herbicide like Valor at planting to help prevent pigweed. Many producers hesitate to use Valor because of the risk of injury. A few points to remember about using Valor are as follows: The recommended rate for peanut is three ounces per acre, spray within two days behind the planter, and, if you have irrigation, apply 0.5 inch after spraying before crop emergence. These points will help reduce the chances of crop injury and also reduce the pigweed population.