The following update was prepared by Clemson peanut specialist Dan Anco.
For peanuts that were planted May 1, we are coming up on the 105 DAP mark. We’ve been getting some decent rain recently that should help with pod fill for peanuts that we dry earlier. Hopefully we get what we need there and then get enough dry weather when it comes time for digging and combining.
Seeing Spots: This is a good time to take a close look at how much leaf spot we might have in different parts of the field. The best way to do this is to bend the plants back to be able to see all the way down to the bottom of the canopy. Often times late leaf spot gets started down in the bottom and works its way up from there.
Late leaf spot typically shows up dark brown, with the best indication that it is late leaf spot being the presence of tiny raised bumps (spores) within the spot on the underside of the leaf. A hand lens helps make it easier to see. Chemical burn can show up differently, and one of the ways it shows up is a spot with a lighter gray/brown center. Chemical burn spots do not have raised spores.
Always a good idea to look at all the varieties, even Bailey. If we start seeing disease buildup, this time of year when the canopy is bigger it may be good to think about using a product with systemic activity (most premium products have systemic activity, check the Production Guide for more details). This helps when complete surface coverage might be difficult in thick canopies. If maturity and weather cooperate, the 105 DAP spray may be the last one for Virginia types. Runner types typically will have at least one more. When possible, it can be a good idea to include Bravo (chlorothalonil) in the last spray of the season. This can help reduce fungicide-resistant populations from surviving over into the next year. Here are some more leaf spot photos: Leaf spot pictures
Foliar Feeding: When seeing signs of feeding on peanut leaves, a lot can look similar. Because of this, it is always best to be able to get a positive identification on an insect pest before we spend time and money putting out an insecticide that may or may not be best for each individual situation. That being said, sometimes we can get a hint at what might be going on by taking a look at the damage on a leaf. If we see feeding damage at random places on the leaf, that doesn’t tell us much. However, if the feeding damage looks like it is symmetrical (damage looks like the same shape to the left and right of the main mid-vein of each leaflet, see attached pictures), that is an indication that the feeding took place at night when the leaves are folded.
The granulate cutworm likes to feed at night (when the leaves are folded) and hide in soil or under fallen leaves and plant litter on the ground during the day. This doesn’t mean granulate cutworm is always to blame when we see symmetrical damage, but it does give us a possible clue about where we also need to be looking. Again, always best to get a positive ID on what is causing the damage before selecting a product to use. See the Production Guide for product recommendations. Typical feeding defoliation thresholds are about 20 – 25% defoliation.