Valor is a very important tool in the fight against pigweed in peanuts. Peanut fields that were hit with heavy rainfall at the cracking stage has had some injury this year. Here are some words from UGA Weed Scientists, Dr. Eric Prostko, on Valor injury.
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 UGA 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) (Tables 1 and 2).
3) Recent UGA research conducted by Drs. Jason Sarver and Scott Tubbs would suggest that there is no yield or economic benefit to replanting a peanut field if populations are at least 2.5 seed/ft (single row) or 3.0 seed/ft (twin row). Thus, 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. Today, I found numerous peanut plants in my untreated plots (i.e. no herbicides) that are exhibiting this symptom (Figure 2). Many other factors can cause j-rooting including individual seedling vigor, environmental conditions (cold/wet), and soil compaction.