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Week of April 17 – Questions and Answers (Prostko)

Here are some questions (and my answers) that I received this week from various county agents and other clients.

1) If Zidua 4.17SC (pyroxasulfone) is applied postemergence for the residual control of pigweed, annual grasses, and tropical spiderwort, what are the labeled stages of growth for application in field corn, soybean, and peanut?

field corn = spiking up to V8 (this is later than what is currently listed in the 2023 UGA Pest Control Handbook)

soybean = cracking up to V6 (Personally, I would prefer after the soybeans have fully emerged and are growing well)

peanut = cracking up to beginning pod development (R3)

2) How do non-Liberty (glufosinate) tolerant field corn hybrids respond to off-target movement of Liberty?

ASC and and I both think that drift rates are likely around 1/100X and lower.  I do not have any local data from Georgia but check out the following information from LSU.  These data suggest that Liberty rates ≤ 1/50X will cause less than 5% yield losses.

Here is a picture of Liberty injury on field corn.

3) Where can I get information about soybean variety tolerance to metribuzin?

The following table is listed in the 2023 UGA Pest Control Handbook (page 280):

For additional soybean cultivar/metribuzin tolerance information, check out the following from the University of Arkansas:


When considering using metribuzin on soybean, cultivar tolerance is very important but there are other factors to consider as well including application rate, soil texture, OM, pH, and planting depth.  Growers should read metribuzin labels very carefully prior to use.  Here is a list of soybean herbicides than contain metribuzin.

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