August 11, 2014 Peanut Scouting and Crop Report
Sclerotinia has been very active this summer due to several spells of cool wet weather. Regrettably, similar weather patterns are predicted. Additionally, reports indicate that the fungicide commonly used to control this disease, Omega, is in short supply. Options to consider include are:
1) Endura at 8-10 oz/acre is effective against Sclerotinia blight. In NCSU trials, Endura has performed as well as the 1.5 pt/a rate of Omega. It does not persist quite as long as Omega, lasting 14-21 days vs. 21-28 days
2) Reduce the rate of Omega. For less challenging situations, one can stretch the Omega supply by using 1 pt/a instead of 1.5 pt./acre. However, there is a noticeable decrease in control at this lower rate under high disease pressure.
3) A high rate of Fontelis (applied at 1.5 pt/acre) will give statistically the same control as 1 pt/a Omega. However, observation of disease incidence, especially in high disease pressure situations, may not be quite as good as desired. Fontelis will provide leaf spot and stem rot control in addition to controlling Sclerotinia blight.
For all applications of products for Sclerotinia Blight, use a higher volume application (20 gal/acre). Complete coverage of the fungicide to the plant is very important. Many infections start on or spread to leaves and to areas of the stem away from the crown. Use hollow cone nozzles for best coverage. Remember too that evidence shows that utilization of Bravo will aggravate Sclerotinia Blight and should be avoided if possible.
LEAF SPOTS, LEAF SCORCH AND OTHER LEAF INJURY
Leaf spots, leaf burns, chemical injury to leaves and other similar symptoms are more common to peanuts than other crops. As noted in tobacco and soybean posts, leaf spots or scorch has been a common problem this year due to ideal climatic conditions. Too, producers often tank mix a variety of products within a single application. Yet, impacts of this application may not be visible for several weeks. The bottom line is that peanut crops often have unexplained leaf spots complicating management decisions. Do not assume that a leaf spot is necessarily the onset of disease. Many are simply slight injury from pesticide applications that will not impact yield. Positive identification of any potential disease is the first step in management. Also, keep in mind that not only are we to protect the crop against yield or quality loss, we need to protect fungicide products against potential fungicide resistance. This limits the number of applications some products may be applied. If in doubt, contact the N.C. Cooperative Extension for assistance.
Follow the author, Mike Carroll on Twitter at @mcarroll_craven
The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by the N.C. Cooperative Extension Service nor discrimination against similar products or services not mentioned. Individuals who use agricultural chemicals are responsible for ensuring that the intended use complies with current regulations and conform to the product label. Be sure to examine a current product label before applying any product.