Peanut Injury Update (Prostko)

In the past 2 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 (Figure 1).  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 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) (Figure 2 + 3).

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 plants/ft (single row) or 3.0 plants/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 4).  Many other factors can cause j-rooting including individual seedling vigor, environmental conditions (cold/wet), and soil compaction. 

Figure 1.  Valor Injury in Peanut

Figure 2. Peanut Yield Response to Valor - 2009

Figure 3.  Peanut Yield Response to Valor - 2013

Figure 4.  J-rooted peanuts not treated with any herbicide.