In the past two days, I have received numerous phone calls, texts, smoke signals, homing pigeons and e-mails about peanut injury caused by Valor.  Peanut fields planted the week of May 5 that were hit by the heavy rains on May 14-15 are likely to have some level of injury. 

Here are a few thoughts to consider:

  1. Valor injury should not be a surprise to anybody since this phenomenon has been observed for 13 years.  Cracking peanuts (+1-2 weeks) treated with Valor that receive heavy rainfall will be injured almost all the time!!!
  2. There is a good amount of University of Georgia data to suggest that, in most cases, the peanuts will recover from this injury without yield loss even at a 2X rate (i. e. 6 oz/A).
  3. Recent UGA research conducted by Dr. Jason Sarver and Dr. Scott Tubbs would suggest that there is no yield or economic benefit to replanting a peanut field if populations are at least 2.5 plant/ft (single row) or 3 plant/ft (twin row). I would not worry too much about Valor injury unless plant populations fall below these levels (assuming the stand is uniform and not skippy). 
  4. Contrary to older dogma, peanut j-rooting is not always caused by herbicides such as Dual or Warrant. I found numerous peanut plants in my untreated plots (i.e. no herbicides) that are exhibiting this symptom.  Many other factors can cause j-rooting including individual seedling vigor, environmental conditions (cold/wet), and soil compaction.

Prostko is a weed specialist with UGA Extension.