by Thomas Isakeit, Professor and Extension Plant Pathologist, College Station, TX.
Until recently, Topguard Terra (flutriafol), which is used for control of Phymatotrichopsis root rot of cotton (“cotton root rot”), was labeled only for application at the time of planting. There are two at-planting methods: a T-band application or a modified in-furrow application. Now, growers have additional options that allow application before or after planting.
The Texas Department of Agriculture has approved a FIFRA a 2ee supplemental label for additional methods of application. The fungicide can be applied up to 30 days before planting 2-4 inches directly below where the seed is to be planted. The use of equipment with GPS guidance systems may ensure proper placement.
The fungicide can also be applied pre-emergence in a 3-4 inch band behind the planter press wheel, it can be applied over the top to 1-2 leaf cotton, and it can be applied as a directed spray to the base of 2-4 leaf cotton. With these methods, rain or overhead irrigation is needed afterwards to activate the fungicide. Additionally, the Environmental Protection Agency recently approved an amendment of the Section 3 label to allow application through the drip tape. The tape must be directly below the cotton and run in the same direction of the row and should be no deeper than 12 inches below the soil surface.
As this information is recent, at this writing, I have not found the label amendments posted yet to the label websites that I use. Growers should either continue to check the websites, or their dealers, for the label, as they will need to have the amended label when they apply the fungicide with these additional methods.
These alternative methods are intended to minimize the risk of phytotoxicity that sometimes occur when Topguard Terra is applied at planting and are based on field experiments. Growers should consider doing a small trial of their own to compare a new (to them) method of application with the method they currently use, and also leave a small, non-treated area in the field to compare performance.
Detailed information about cotton root rot and its management can be found in a factsheet at cotton.tamu.edu/Nematodes/16_FC010_CRR.pdf.
If you have any questions, contact me at (979) 862-1340 or firstname.lastname@example.org.