Crop Scene Investigation - 50 Solved: What caused Roman's soybeans to struggle?

Tuesday, March 4, 2014

Roman's glyphosate-tolerant (GT) soybeans were suffering from dicamba injury.

"Glyphosate is a great weed killer, but it's also a great soap," explains Syngenta agronomist Shawn Brenneman.

Although Roman had cleaned his sprayer properly, the glyphosate he left in the tank worked as a cleaner while the sprayer was parked for three days and pulled out enough residual dicamba herbicide from the sprayer lining to damage his crop.

Roman had sprayed dicamba on his corn and done a good job cleaning out the sprayer before moving into GT soybeans. But when rain caused him to quit spraying his soybeans, the remaining glyphosate left in the tank effectively scrubbed dicamba residue from the liner.

When Roman started spraying again, the dicamba in the glyphosate caused the cupping and crinkling of newer soybean leaves and the twisting of stems and petioles – typical injury associated with these plant growth regulator herbicides.

Brenneman says growers can't always prepare for every situation, especially when application windows are closing during spraying. "But it's important to make sure you really are cleaning out that tank in between crops as best as you can.

"The best approach is to only mix up enough spray for that day. Try to avoid having chemicals sit in the spray tank for any longer than the time it takes to spray it out," adds Brenneman.

We were overwhelmed with correct solutions for this one. Congratulations to Dennis Driedger, Wheatley, for his correct answer. Dennis notes: "We had this happen with Eragon residue." BF