Many cost-conscious cotton producers rolled the dice each of the last three years and left off an in-furrow fungicide at planting. Fortunately, they got a break from the weather and experienced little or no problems with seedling disease. But is this the year they get burned?
Research indicates that favorable weather at planting has led to a three-year decline in losses to seedling disease in west Tennessee, according to University of Tennessee plant pathologist Melvin Newman. “In 1997, we lost 9.5 percent of our crop to seedling disease; in 1998, 7 percent; 1999, 5 percent; and 2000, 4 percent.”
That trend extends across the Mid-South, where seedling disease losses are down from what they were in the late 1980s and early 1990s. “The greatest reduction in losses has been in the Mid-South,” said Don Blasingame, group coordinator for the National Cotton Council's (NCC) Root Health Work Group. “Some of the reduction may be attributed to better-quality seed, but environmental conditions at planting have also played a role.”
The problem is that declining losses may have given producers a false sense of security, according to Blasingame. But he stresses, “Every year is a new ballgame. Just because a grower didn't benefit greatly from an in-furrow fungicide last year is no bet he won't need one this year.”
One thing to consider is that during the last three years, much of North America was under the influence of an El Niño-La Niña weather cycle. El Niño-La Niña produced mostly warm springs in the Delta.
Most meteorologists are now saying that the phenomenon is dying and that the continent's weather patterns should soon return to normal.
Whether or not this could mean wetter, cooler weather this spring is anybody's guess. But if it's cooler — not necessarily wetter — this could be a year when an in-furrow fungicide contributes significantly to your bottom line.
Newman noted that in Jackson, Tenn., in 1997 (the year that almost 10 percent of west Tennessee's crop was lost to seedling disease), the minimum daily May temperature regularly dipped down into the 40s. In 1998, 1999 and 2000, it was much warmer because of El Niño-La Niña.
Newman stressed that 1997 was a dry year, while the following three years were rainy during May. “So it really isn't so much the rain that leads to an high incidence of seedling disease. It's the cold weather, the cold soils. If it's cold, you're going to have seedling disease.”
Newman noted that in 1997, his research indicated that an in-furrow fungicide provided an average of 217 more pounds per acre than untreated plots. Stand counts were also improved in most of the treatments in which an in-furrow fungicide was used.
In 1998, a warm, wet year, there was very little difference in yield or stand count between treated and untreated plots, according to Newman. “In 1999 and 2000, we had similar results. The treatments were not much different from the checks.”
Many growers wonder if the occasional benefit from using an in-furrow fungicide is worth the cost of doing it every year? According to a 12-year study of the practice conducted by Newman, it is. “The fungicides made a $100 per acre clear profit on the average each year. That's $1,200 over the 12 years. If you had 1,000 acres, that's $1.2 million. So it adds up.”
All cotton seed used for planting is treated with at least one fungicide, many times two. But under conditions favorable for severe seedling disease, seed treatments do not provide adequate protection, according to Patrick Colyer, plant pathologist with Louisiana State University. “Under those circumstance, an in-furrow fungicide provides the best level of protection.”
Planter or hopper box treatments are the least effective of the supplemental treatments, but are better than no additional treatment beyond the standard seed treatment. In-furrow fungicides are also very important when an in-furrow insecticide is used.
According to a 1999 Auburn University study by plant pathologists William Gazaway and Kathy McLean, an in-furrow fungicide with an average cost of $16.70 per acre generated additional lint valued at $64.80, giving the grower a return on his investment of $48.10.
“Using an in-furrow fungicide is cheap insurance for the grower,” Gazaway said. “Our research has clearly shown that most years, it not only protects against economic loss, it actually makes the grower more money than trying to get by without one.”
Alabama's annual loss to seedling disease is about 6 percent.
Newman stresses that another option for growers is to wait until temperatures warm up before planting. “The best tool for a producer may be a soil thermometer.”
The downside of that alternative is that it narrows the window for planting considerably, he added.
The common pathogens in the Mid-South are rhizoctonia, thielaviopsis, fusarium and pythium. Common names include seed rot, seedling rot, root rots, soreshin and damping off.
Pathogenic activity from these diseases can continue to impact the seedling until emergence from the soil. If the seedling survives, root damage can continue and the taproot may be affected. While the plant will try to compensate by producing secondary roots, the damage will continue to impact the plant throughout the season.
The NCC has been tracking seedling disease since 1952. During that period, growers lost an average 2.8 percent of their crop annually to seedling diseases. In 1999, the value of bales lost totaled more than $2 million across the Cotton Belt.