Stripe rust resistance may soon make the list of considerations when Texas Panhandle producers select wheat varieties, says a Texas Cooperative Extension agronomist. Fortunately, those varieties have tested well in this region.
Brent Bean, Extension agronomist in Amarillo, says stripe rust is not expected to be a constant problem, but was significant this year.
“It is unlikely we'll experience again anytime soon the widespread infection levels that we saw in 2005,” Bean says. “However, I believe stripe rust is here to stay and we will likely be able to find it in the Panhandle at some level every year.
“For it to be a significant problem, we will have to have the weather conditions (prolonged cool, wet weather in the spring) to cause it to spread rapidly.”
Stripe rust is new to the Panhandle, first showing up three years ago. It is now the dominant rust in the area.
It looks similar to leaf rust, except the rust pustules tend to line up between the leaf veins, giving it a striped appearance. Stripe rust thrives in temperatures from 46 degrees to 58 degrees when moisture is present, while leaf rust prefers warmer conditions and thrives in 70 degrees temperatures.
In field trials this year, those with the highest stripe rust infection level suffered yield reductions of around 20 bushels under both dryland and irrigated conditions.
“When comparing stripe rust tolerant varieties TAM 111 and Jagger to the susceptible variety TAM 110, yield dropped 37 percent in dryland trials and 23 percent in irrigated trials by stripe rust,” Bean says.
Varieties with stripe rust tolerance were the stars in 2005. The most tolerant varieties include TAM 111, AgriPro 4342, Overley and Fannin. These were followed by Cutter, Jagger, 2145, Deliver, Jagalene, HG-9 and T 81, with moderate to moderately susceptible tolerance.
In irrigated trials, TAM 111 was the best variety for the second year, Bean says. TAM 111 had the highest yield average across locations by more than eight bushels, while yielding in the top 20 percent in five of six locations.
TAM 111 is one of the newest varieties to be released by Texas A&M and is marketed by AgriPro. This relatively tall variety has good straw strength. Seed should be available this fall, but growers should book seed early, Bean says.
Other varieties yielding in the top 20 percent of at least three of the six locations were T 81, Texas A&M experimental TX01D3232, AgriPro 4342 (experimental), Overley, Jagger and Jagalene.
T 81, a variety from Trio Seed in Colorado with TAM 107 in its background, was tested for the first time this year. The two experimental varieties will not be available for at least two years.
Jagger and Jagalene have performed well in area trials for several years, he said. Overley was released by Kansas State University in 2003 and has both Jagger and TAM 107 in its pedigree. In 2004, irrigated Overley yields were only average, Bean says.
Varieties with stripe rust tolerance also tended to yield best under dryland situations. Varieties yielding in the top 20 percent in at least three of the six locations were AgriPro 4342, Overley, TAM 111, T 81, Cutter, Fannin and the A&M experimental TX00V1117.
Fannin is an AgriPro release with reported excellent fall forage production, he says. This is the second year for widespread testing. In 2004, Fannin yield was only average. Overley has been in trials for the last two years and was in the top 20 percent of dryland varieties in both years.
While stripe rust was the limiting yield factor this year, each year is different and all varieties have positive and negative characteristics, Bean says. Many rust-resistant varieties are susceptible to leaf rust and none are resistant to greenbugs.
In addition, he says, just because a variety was stripe rust tolerant in 2005, does not mean it will remain tolerant in 2006. For a brief discussion of each variety in this year's trials, go to http://amarillo.tamu.edu/programs/agronomy/publications/Wheat/index.htm.