By Kay Ledbetter
Texas A&M AgriLife Research in Amarillo will participate in a $3.3 million grant to look at wheat diseases caused by mite-vectored viruses, according to Dr. Charlie Rush, plant pathologist.
The project, “A Predictive Model to Increase Adoption of IPM of a Mite-Virus Disease Complex in Wheat,” is a Coordinated Agricultural Project, or CAP, funded by the U.S. Department of Agriculture’s National Institute of Food and Agriculture.
Rush and two others in his plant pathology unit – Dr. Fekede Workneh and Jacob Price – will be part of a 22-member team from Texas, Oklahoma, Kansas, Colorado, Nebraska, Montana and North Dakota universities and the U.S. Department of Agriculture-Agricultural Research Service.
According to the study outline, the Great Plains region of the U.S. from Montana south to Texas produces more than 1 billion bushels of wheat annually or 50 percent of U.S. wheat production. In the southern half of the region, the use of wheat to supplement forage for livestock adds significantly to the importance of the crop and the economic vitality of the region. And stakeholders have identified wheat viruses as a major priority that constrains wheat production.
Wheat streak mosaic virus will be the primary focus, Rush said, along with Triticum mosaic virus and High Plains virus. All three viruses are vectored by the wheat curl mite and cause similar disease symptoms on infected wheat plants. The mite can’t fly but is carried by the wind from plant to plant, and there is no chemical control at this time.
“To control the diseases caused by these viruses, we really have to learn to control the mite,” he said.
Dr. Gary Hein, a University of Nebraska entomologist, is the program director. Rush said he and Hines have been talking for years about this project and have finally pulled everything together.
The scientists plan to determine the impact of environmental conditions, alternate hosts and management tactics on mite populations and disease incidence, as well as the risk in geographically and environmentally diverse production regions across the Great Plains.
They will identify the primary interactions that occur in this wheat-mite-virus complex across the region and increase producer implementation of integrated management principles for managing the complex across the Great Plains, Rush said.
“We plan to develop an accurate forecasting model that will improve growers’ ability to anticipate and take action,” Rush said. “We plan to deploy that model through Extension and educational curricula.”
Wheat streak commonly starts at the edge of a field and then the mite, which is carrying the virus, will move on the wind across the field, he said. When the mite begins feeding on a plant, the virus is transmitted and the plant becomes infected. Once the plant is infected, it takes about a week or two, depending on temperature, for the disease symptoms to appear.
One of the things the AgriLife Research scientists will study is the disease threshold for management purposes.
“We know in March and April that you can tell if wheat streak is in the field and how widespread it might be,” Rush said. “At that time, we can determine if the producer needs to discontinue fertilizing and watering, which he might be applying extra of, if he thinks the field is yellow due to reasons other than wheat streak.”
If it is yellow due to wheat streak, he said, it will not get better no matter how much water and fertilizer are added, so the producer is just wasting money on those inputs.
“Once wheat streak gets going in a field, there’s really nothing a producer can do,” Rush said. “We want to look at management practices that might keep it from getting that bad. We know planting date is a key factor. Planting late breaks the cycle, but in this region, dual-purpose wheat is the norm and leaves fields open to early infestation by the wheat curl mite.”
Rush said this study will allow them to look at the problem from a Great Plains’ perspective, instead of the state view previously used.
“We want to first understand the common areas, and once we understand the primary factors, we can develop a disease risk assessment model,” he said.
This grant will take advantage of existing facilities and personnel, such as those associated with the Great Plains Diagnostic Network, which is already set up in all these states, Rush said. That group already coordinates diagnostics of diseases and trains first detectors.
“Being able to access those scientists’ expertise made it simple to pull together a strong team to work on this issue,” he said.
The team will replicate the same work from Texas to Montana, Rush said, planting and monitoring a common susceptible control wheat variety; varieties such as Ron L, Mace and TAM 112, each of which offers a different type of resistance; and local cultivars from each state.
“We will record weather data, cultural practices and even hail storms,” Rush said. “Hail plays an important role on volunteer and wheat streak the following year. In our area and in Oklahoma, we will focus to a high degree on native pasture and Conservation Reserve Program grasses, because we think those are important to the vector and disease carryover.”
Scientists will do individual studies and then group studies so the entire project will provide a tremendous amount of information over the five years of the grant, Rush said.
Helping guide the study will be a program advisory board made up of growers, industry and commodity representatives from each state who will help identify the areas that impact them the most.
“With their help, we will be able to identify the most important aspects of wheat diseases caused by mite-vectored viruses and get something that is useful and valuable to the producers,” Rush said.
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