Peanut Pest Update

Our peanuts have been lapping for a few weeks now. They are looking good so far. We are more or less 60 days old now. Seeds are developing inside pods, and growers are starting another round of fungicides. Here is some information from specialists concerning insects and disease:

Insects

Here is an update from UGA Extension Entomologist Dr. Mark Abney:

There continues to be lesser cornstalk borers (LCB) in Georgia peanut fields, and I do not see any reason that should change over the next few weeks. Interestingly, most of the heavy pressure has not been in the Southwest but in the middle and eastern portions of South GA. I expect that some of the infestations we were seeing in irrigated fields prior to the vines covering the row middles will be diminishing as irrigation water is applied with greater frequency.

I have not received a call about two spotted spider mite on peanut in 2016, but I am betting it is coming soon. Mites have been hanging around on cotton now for several weeks, and with continued hot, dry conditions I think we will be seeing mites move into peanut fields. If this happens, it is going to create a lot of headaches for growers, Extension agents, and crop consultants. 

1. We need to catch mite infestations early to have any chance of getting good control. 
2. With the one miticide available for use in peanut (Comite), we need to use a minimum of 20 gallons of water per acre, and two applications may be needed because egg mortality is low.
3. The yield potential of some of our non-irrigated peanut acres is rapidly deteriorating; knowing when to pull the plug on inputs in these fields is going to be difficult, and most growers will be reluctant to “give up” on the crop. When making treatment decisions, we need to be realistic about the crop we already have set and our potential to add harvestable pods to it.
4. I say this a lot, but we need to be sure to avoid pyrethroid insecticides in fields where spider mites are present or in fields at high risk for mites (hot and dry) in areas where mites have been found in surrounding fields. There are a couple pyrethroids that will suppress mites, but “suppression followed by resurgence” is a better description of what usually happens.

Rain tends to be the best treatment for LCB and spider mites, but a single rainfall event will not eliminate either of these pests once they are established in a field.

I have not heard of damage from potato leaf hopper, but have seen threecorned alfalfa hopper. Here is a picture of their damage. Immatures girdle the stem, and sometimes adventitious roots will grow.

Three-cornered Alfalfa Leaf Hopper damage

Disease

Tomato Spotted Wilt Virus

This week we saw some spotted wilt, and there are other reports of spotted wilt – especially early planted peanuts.We are having the right conditions for white mold with the heat and afternoon rain showers. Only timely fungicides will protect us during this time. Here is a link to the 2016-PeanutRxwithVariousFungicidePrograms for the companies that provide them (BASF, Bayer, DuPont, Nichino, & Syngenta). We watch for white mold outbreaks now.

Brooks County Ag Agent Stephanie Hollifield makes a good point, that “If you have missed the afternoon thunderstorms and are experiencing the other extreme of dry weather, keep in mind that white mold control can be more difficult during drought. This is due to the fact that, dry weather prevents the ease of movement of the fungicide product from leaves of peanut plant to our target application spot in the crown of plant. To ensure white mold control products get down to crown/ground; irrigate if possible or apply white mold control fungicides with presence of dew on peanut plant and/or while leaves are still closed up.”

I’ve also had questions of mixing other products now. We should use caution with tank mix applications, especially during extreme hot and dry weather. The likelihood of plant burn can increase with any product, with the increase in environmental temperatures and tank mix partners.