It’s September 24 and we hit 98 degrees yesterday and today here at the research station, and still no rain. A hot, dry wind is blowing across the fields and for all it’s worth, it feels like Arizona, not Virginia. Populations of spider mites which thrive in this kind of environment are exploding in peanut fields across the region. Populations are so large that they are forming pencil eraser sized balls of solid mites on the tips of the upper branches of the peanut plants. Their feeding has extracted the last bit of moisture, what little was left, from already struggling plants. The ONLY solution is to DIG THOSE PEANUTS. We are very close to the normal peanut digging window for Virginia and with the dry conditions, there is no advantage to waiting. In normal years with normal soil moisture, we encourage growers to wait as long as possible to begin digging. By waiting, you allow nuts to gain more ‘meat’ content which improves the grade and value. Not so this year. In the near total absence of soil moisture, peanuts have essentially stopped maturing. What you have is it and you might as well dig. Some are waiting to dig until they get some moisture which will improve digging conditions. Fields with heavier natured ‘tight’ soils will be almost impossible to dig efficiently unless it rains. But I still do not recommend treating for mites. Their feeding has not compromised vine strength, which is the biggest concern late in the season. Where late season plant diseases can cause vines to deteriorate which causes them to shed pods during the digging process, spider mite feeding is not having the same effect. Even in fields with the heaviest infestations, vine strength has not been compromised. My advice, just dig them as soon as you can. But be prepared, after the vines are inverted, mites will move to the exposed tap roots. It will look bad, but it is of no economic importance.

It is not surprising that we are getting reports of spider mite build-ups in peanut fields. There are areas that have been fighting this dry weather pest for several weeks. These newer outbreaks are particularly bothersome as they are coming so close to the end of the season. D. Rick Brandenburg (NCSU) and I have done a lot of work on how to achieve the best control of spider mites in peanuts. There are several limiting factors, not the least of which is the limited number of products registered for spider mite control in peanut. There are only three products currently labeled, Danitol, Brigade and Comite. For reasons that must have to do with marketing, Comite has not been readily available to Virginia growers for the last 3 or 4 years. That leaves Danitol and Brigade (= Capture) which are both pyrethroids. These products if applied with high spray volume (15 + gpa) will provide good knockdown of adult and immature mites. But, neither kills the eggs so if applications are made to fields where there are a lot of eggs, these hatch in 2 or 3 days and the infestation begins again. Our work showed that the only way to make these products work well was to make two sequential applications about 5 to 7 days apart. The first application knocks down the adults and immatures, and the second gets the new hatchlings, thus breaking the cycle. But, this late in the season when digging will begin soon, we are recommending that if mites are doing a lot of damage and need to be controlled, make a single application using the highest labeled rate, knock them back, and hope for the best.