Amarillo, Texas
July 28, 2005
Stripe rust resistance may need to be added to
the list of considerations when producers make wheat variety
selections in the future, said one
Texas Cooperative
Extension agronomist. Fortunately, those varieties have
tested well in this region.
Dr. Brent Bean, Extension agronomist in Amarillo, said stripe
rust is not expected to be a constant problem, but it was
significant this year.
"It is unlikely we'll experience again anytime soon the
widespread infection levels that we saw in 2005," Bean said.
"However, I do 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 again have to have
the weather conditions (prolonged cool, wet weather in the
spring) to cause it to rapidly spread," he said.
Stripe rust is new to the Panhandle, first showing up three
years ago, Bean said. 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 F to 58 F when
moisture is present, while leaf rust prefers warmer conditions
and thrives in 70 F temperatures.
In field trials this year, those with the highest stripe rust
infection level had yield reductions of around 20 bushels under
both dryland and irrigated conditions, he said.
"When comparing stripe rust tolerant varieties TAM 111 and
Jagger to the susceptible variety TAM 110, yield was reduced 37
percent in dryland trials and 23 percent in irrigated trials by
stripe rust," Bean said.
Varieties with stripe rust tolerance were the stars in 2005,
Bean said. The most tolerant varieties were 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 said. 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 being marketed by AgriPro, he said. This relatively
tall variety has good straw strength. Seed should be available
this fall, but growers should book seed early, Bean said.
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 looked at for the first time this year, Bean
said. The two experimental varieties will not be available for
at least a couple of years.
Jagger and Jagalene have performed well in area trials for a
number of 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 said.
Varieties with stripe rust tolerance also tended to yield the
best under dryland situations, Bean said. 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 said. This is the second year of its widespread
testing. In 2004, yield of Fannin 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, Bean said.
While stripe rust was the limiting factor this year on yield,
each year is different and all varieties have positive and
negative characteristics, he said. Many rust-resistant varieties
are susceptible to leaf rust and none are resistant to
greenbugs.
In addition, Bean said, 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.
Writer: Kay Ledbetter |