What's Up This Week (Prostko)

A couple of interesting things to share with you this week:

1) Check out the following picture sent to me by Dr. Alan York (NCSU).  On day 1, Mr. Peanut Grower mixed 2,4-DB and dry manganese sulfate in 700-800 gallons of water with no problems.  On day 2, Mr. Peanut Grower mixed the same combo with only 100 gals of water and OH NO!!!!.  A great advertisement for pre-slurrying dry formulations prior to mixing in a big tank.

2)  Much ado in the the Mid-South about off-target movement of dicamba.  We have experienced a few problems in GA but nothing compared to what's going on there.  Just recently, I was asked how non-dicamba soybean yields could be affected by off-target movement of dicamba.  Although soybeans are very sensitive to dicamba and low rates will cause leaf cupping and epinasty, vapor drift rates (1/1000th X) and particle drift rates (1/100th X) will likely cause yield losses of < 9% depending upon the soybean stage of growth.

3) Current list of dicamba tolerances (i.e. how much residue in a crop is legal) can be obtained at the following web-site:

https://www.law.cornell.edu/cfr/text/40/180.227

Recent Tank-Mix Issues (Prostko)

Last week, I received a few calls and pictures from some folks about tank-mixes and peanut injury (Figures 1 and 2).  I will remind you that there is nobody on the planet that can assure any peanut grower that a tank-mix will be 100% safe and 100% effective all the time. There are too many variables to consider including the number of products in the spray tank, GPA, air temperature, humidity, leaf wetness, overall peanut plant health, and time of day.   I think part of the problem last week was our higher than normal temperatures (Figure 3).  A few tips for growers considering spraying untested tank-mixes:

a) Limit the number of products that are put in a spray tank.  Bite the bullet and make separate applications when practical.
b) Spray early in the morning when air temperatures are lower and the peanut plants have not been baking in the sun all day.
c) Increase water volumes from 10 GPA  to 15 GPA (less concentrated spray droplets).

Figure 1.  Peanut response to Convoy + Alto + Bifenthrin fb Select + COC
 1 hour later (i.e. really a 5 way tank-mix)

Figure 2.  Peanut response to Propulse + 2,4-DB (i.e. really a 3 way tank-mix)

Figure 3.  Maximum air temperatures, Attapulgus (GA), June 30 to July 7, 2015, 2016, 2017
(Source:  UGA Automated Weather Network)