The following update was prepared by Clemson Peanut Specialist Dan Anco.
While some of this year’s peanuts are right at 45 days old, others were planted about 60 days ago. Classically, 60 DAP marks the beginning of the critical period to manage white mold in SC. With regards to leaf spots, 60 DAP is also when we typically would start supplementing our fungicide programs with chemistries beyond chlorothalonil and tebuconazole (Bravo + Folicur). We have lots of products to choose from, and the production guide lists relative efficacies of the majority of available chemistry products (page 52).
As a reminder to help reduce the effect of possible strobilurin resistance in late leaf spot populations, when applying azoxystrobin (Abound) or pyraclostrobin (Headline) we can buffer ourselves by mixing these with different chemistries, in addition to limiting our total strobilurin application to a max of 2 per season per field. Elatus and Priaxor are jug mixes of these individual group 11 strobilurins in combination with a group 7 carboxamide: benzovindiflupyr + azoxystrobin in the case of Elatus and fluxapyroxad + pyraclostrobin in the case of Priaxor. Convoy (flutolanil) has been an excellent product for white mold, but it needs to be tank mixed with products that have foliar disease activity (e.g., 1 pt Bravo + 5.5 fl oz Alto) to also manage leaf spots. As an added boost in managing high white mold disease risk situations, we can apply fungicides at night when the peanut leaves are folded up. This helps get more active ingredient closer to their action site in the soil for white mold, particularly when canopies are larger. If we do spray at night or in the early morning before the leaves unfold, we’ll need a systemic product to cover the bases for leaf spot (page 48 to 51). While the chlorothalonil in Bravo is not systemic, many other options are.
Leafhoppers are also becoming more noticeable in some fields. Below is a picture of the yellow V-shaped hopperburn they leave on the tips of leaflets after they feed. This burn doesn’t typically appear until about a week or so after the actual feeding.
The threshold for treating leafhoppers is 15 to 20% hopperburn across the entire field, with adult leafhoppers still present. The adults are about 3 to 5 mm long and are light green to yellow.
Leafhoppers are one of several pests (spider mites included) that typically start on the edge of a field and then move inwards. This is good to keep in mind when evaluating each field so that we don’t pull the trigger too soon. Currently labeled options for leafhoppers are broad spectrum chemistries (page 55). This warrants caution and reserve to prevent flaring spider mites, particularly in and around dry spells.