Development, Maturity
Over the past week, rainfall across the state has ranged from 0.01" (Darlington & Horry Cty), 0.2 to 0.3" (Calhoun/Latta), ~0.83" (Blackville/Orangeburg), to 1.5" (Hampton Cty). Where rain did come in, most of this was earlier during last week where fields are starting to get dry again, with little rain in the forecast for the week ahead. Temperatures ahead are poised to favor continued maturity development. Most of the crop is between 130 days (planted April 20) and 82 days old (planted June 7) today. Worms and moths (mostly corn earworm/tobacco budworm or velvetbean caterpillar) are being seen in limited amounts, but populations recently have been low enough so as not to require treatment. These will be good to continue to keep an eye out for, particularly if conditions stay dry. As maturity sampling increases, taking samples from different spots helps to take into account field variability. It is not uncommon for a maturity sample to vary by 10% or more between different spots, and this can be more common in dryland fields, particularly dry sandy spots.
Leaf Spot, White Mold
Leaf spot and white mold have started expressing more symptoms in a few fields, particularly those with previous histories of elevated disease pressure. TSW infections ranging from spotting to stunting to dead plants are also being seen — but with TSW, we no longer have management options available to us other than making notes for next year. If a canopy is clean from LLS (or has a few spots low in the canopy) and will be dug in 3 weeks, in most cases it will be fine without another fungicide treatment if canopy health is currently good. At the other end of the spectrum, our cutoff for Virginias starting to be defoliated from leaf spot is 40% defoliation, and 50% for runners even if they are not at optimal maturity. If defoliation is just getting started at around 5%, it typically takes about 3 weeks to then get to 40% defoliation (without management). An additional 2 weeks from there would bring it to 80% defoliation. Bravo/chlorothalonil is an excellent treatment for leaf spot and is often beneficial near the end of the season due to its multi-site mode of action, but it only has preventative activity and is not systemic. This can reduce effective canopy penetration; higher spray volumes up to 20 GPA can help, but this is less attractive since it comes with more time spent refilling. Provost Silver has been a reliable fungicide that has provided effective activity during an ongoing LLS epidemic. Lucento has worked well in our trials as well. Depending on the price, Revytek may be another option. In a similar vein with white mold management, if a field had already received two applications of Elatus or of Excalia, with teb as a rotation partner, an application of Convoy or Umbra can be helpful for management by switching active ingredients. Depending on the planting date, PHIs may reduce this fungicide option for earlier planted fields.
Next week:
The 2025 Peanut, Cotton, Vegetable & Fruit Field Day will be held next week on Thursday, September 4 at the Edisto REC.
2025 Peanut Cotton Vegetable Fruit Field Day Schedule
Dan Anco
Extension Peanut Specialist and Associate Professor
Department of Plant and Environmental Sciences
Clemson University – Edisto Research and Education Center
64 Research Road
Blackville, SC 29817
630-207-4926 cell
danco@clemson.edu