Taking the bite out of cotton root rot

Cotton root rot has been a nemesis to cotton more than 100 years. Now researchers are combining even more muscle aiming to stop the dreaded disease.

Texas A&M specialists started looking at flutriafol to control phymatotrichopsis root rot, or PRR, in 2008. Since that time, they have found flutriafol can sharply reduce PRR at low concentrates of just 0.125 pound per acre.

Key Points

Some of the best scientific minds are working to control cotton root rot.

Flutriafol could become available with a Section 18 label by next year.

Both aerial and ground technology is being used to monitor the disease.

Tom Isakeit, AgriLife Extension plant pathologist, College Station, says after three growing seasons of flutriafol applications through 2010, researchers observed:

Liquid treatments with flutriafol at planting appeared to work best on controlling PRR.

Granular applications just didn’t seem to be as effective in 2010.

Putting down flutriafol as a preplant also would not be recommended.

Isakeit says root rot is not as prevalent in East Texas because the sclerotia do not survive in that region’s more acidic soils. Likewise, the fungus is not as bad up on the High Plains of Texas because the colder soil temperatures there make it more difficult for it to survive over winter.

But the vast Rolling Plains with warmer soil temperatures and typically alkaline soil is highly susceptible to PRR, he notes. In fact, cotton root rot was just terrible in many parts of the Rolling Plains in 2010.

While Isakeit, as a pure scientist, tends to be highly conservative in his comments, he says the three years of work with cotton root rot has left him impressed with flutriafol.

“This fungicide is pretty persistent compared to the fungicides I’ve looked at over the years against the fungus,” Isakeit allows.

So in 2011, Isakeit and other specialists will be looking at in-row application for cotton root rot with flutriafol. This in-furrow treatment will involve getting flutriafol on the seed as well as soil near the seed.

Isakeit praises John and Doug Wilde, San Angelo, Texas, cotton growers, for their cooperation in field trials with flutriafol each year since the work began. He also lauds Rick Minzenmayer, Integrated Pest Management agent, Texas AgriLife Extension Service for Runnels and Tom Green counties, for being instrumental in the research from the start, and David Drake, Extension agronomist, for his work.

Bob Nichols, Cotton Incorporated senior director, Cary, N.C., says the several years of work clearly shows flutriafol has great promise in controlling cotton root rot. He hopes the teamwork by Isakeit, Minzenmayer and others will give additional valuable data.

The team’s eventual goal is that after this year of field research, growers can obtain a Section 18 to use flutriafol on cotton in 2012.

Aerial monitoring

Gary Odvody, Texas AgriLife Extension plant pathologist, Corpus Christi, says he feels aerial imaging and mapping of cotton root rot is valuable in showing its presence and a field’s risk of root rot. He says this can show the disease progression — whether it is spreading or staying at a specific location.

Chenghai Yang, agricultural engineer, USDA Agricultural Research Service, Weslaco, Texas, says remote sensing imagery can help pinpoint the specific infested part of a field. That’s important, he notes, as chemical application can be too costly for blanket treatment of an entire field.

Using airborne multi-spectral imagery to detect and monitor root rot progression, the imagery showed that during a growing season, root rot can spread rapidly. In one field, root rot was present at 15% infestation during the middle of the season, but by harvesttime, the field was 40% infested. Another field was so bad that infestation went from 50% to 71% during the season.

Ground-based technology

Alex Thomasson, Texas AgriLife Extension agricultural engineer, College Station, uses a thermal infrared camera on the ground for color infrared imagery. He also takes leaf samples, which must be packed in ice and analyzed quickly.

Thomasson notes cotton root rot prohibits transport of water from the roots to the leaves. In fact, the temperature of the leaves will increase.

He scouts fields from San Angelo to the Thrall area in Texas, looking at how time and moisture play a role in the severity of root rot infestation throughout the year.

All together, some of the best minds in science are working on cotton root rot, but even if flutriafol soon becomes available to growers — perhaps next year — and is effective against root rot, Isakeit cautions growers not to use that as an excuse to turn to monoculture farming of cotton.

Isakeit strongly suggests farmers still use crop rotation. Otherwise, monoculture farming soon could bring them other problems like reniform nematodes.


GET IT OUT: Rick Minzenmayer, Texas AgriLife Extension IPM coordinator (left) of Ballinger, and David Drake, Texas AgriLife Extension agronomist, San Angelo, check boxes and lines on a John Deere MaxEmerge Plus planter while laying down different seed treatments, both liquid and granular, for cotton root rot research on the John and Doug Wilde farm at San Angelo. Work will continue through this year.

This article published in the May, 2011 edition of THE FARMER-STOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2011.