Peanut Grower Magazine Jordan Column Peanut Notes No. 62 2021
In early June in the Virginia-Carolina area the two most critical pests to control are thrips and weeds. Hopefully most growers were able to get adequate suppression of thrips with systemic insecticides applied in the seed furrow at planting. If not, acephate applied to the foliage in a timely manner is important to protect yield. We generally see our best results when this insecticide is applied three weeks after planting. About 50% of growers are making this application, often in combination with herbicides. To get the most out of this treatment, it is important be make the application before the injury is excessive. June is also a good time to firm up the residual weed control you have in fields. As with systemic insecticides for thrips, hopefully the preplant incorporated or preemergence herbicides used were activated and gave adequate control for the first three or more weeks in the season. Paraquat plus Basagran applied with residual herbicides (metolachlor products, Outlook, Warrant, Zidua, or Anthem Flex) is a good option at this point in time. Paraquat can be applied up to 28 days after peanuts emerge but earlier is better, generally three weeks after planting if possible. The Basagran reduces peanut injury from paraquat. Residual herbicides can increase foliar burn but in most cases it is no more than 20% and is transient and not an issue. Of these residual herbicides, Anthem Flex can cause the most stunting but peanuts recover. Warrant can occasionally stunt peanuts as well but that generally happens only when heavy rain occurs and peanuts absorb a substantial amount of acetochlor at one time. Non-ionic surfactant at 1 pint per 100 gallons should be added. As a note of caution, if thrips injury is excessive (in most cases systemic insecticides keep this from happening) do not apply paraquat. Peanuts can handle thrips injury or paraquat injury but not the combination without a significant yield hit.
Our work in North Carolina shows that paraquat, Basagran, and residual herbicides are compatible with acephate. But if thrips injury is excessive, take care of the thrips first and then apply herbicides after peanuts have recovered. We have less information on combinations of paraquat, Basagran and Anthem Flex applied with acephate, and I am concerned about the impact of Anthem Flex if there is excessive thrips injury. We are working on this potential issue in 2021. Some growers will opt out of paraquat and move to Cobra, Ultra Blazer, Storm or Cadre for weed control. Residual herbicides can be applied with these herbicides as well. The key on all of these herbicides is timing. Don’t cut rates and spray small weeds.
During the last part of June growers with Virginia market types will need to apply gypsum. Try not to be too early on the application (we need peanut foliage present to limit movement of soil and gypsum off of beds if we get heavy rains.) For growers in the upper Virginia-Carolina, region we can run into southern corn rootworm damage under irrigation or on soils that are poorly drained or have a fine texture (these conditions promote survival of larvae that feed on pods.) You can use our risk index to decide if chlorpyrifos is needed in those field. Keep in mind that applying this insecticide under hot and dry conditions in fields are at low risk for southern corn rootworm can flare spider mites. This is where the risk index can help you avoid applications when they are not needed and when they can cause a secondary or induced pest like spider mites to become established.
Finally, in late June you will begin thinking about fungicide sprays for leaf spot and stem rot. Our recommendation is applying fungicides beginning at the R3 stage of growth. Chlorothalonil is an important part of our leaf spot control programs and should be included in the first spray. More on the remaining sprays in your fungicide program in the July column.
Use good stewardship with all of the products I have mentioned for pest control. They all carry risk to the person mixing and making the application and to environment. When handled and applied properly the risk from pesticides is minimal. When pests are present the benefits of pesticide use far exceeds the risk of using them. But this statement carries a major assumption. We need to be diligent in making sure we stay safe when we use them and we need to keep pesticides in the field where they belong. And of course, applying the correct product at the correct time (that are legal for the peanut crop) is essential.