Wheat streak mosaic, volunteer issues to be highlighted at May 17 field day

Writer: Kay Ledbetter, 806-677-5608, skledbetter@ag.tamu.edu
Contact: Dr. Charlie Rush, 806-354-5804, crush@ag.tamu.edu

AMARILLO – During the May 17 Wheat Field Day, Texas A&M AgriLife Research will highlight a “real-life” research study that will provide a firsthand look at what happens when volunteer wheat is not controlled.

The field day will begin in the Porter Wheat Building at the AgriLife Research farm west of Bushland with registration at 8:30 a.m. and tours at 9 a.m. After two hours of tours, attendees will be welcomed to visit several booths and posters before a noon lunch and program.

“I’m really excited about the field day, I think we have some things planned that will be a little bit different this year,” said Dr. Charlie Rush, AgriLife Research plant pathologist. “But from my perspective, this one stop is going to be a great demonstration of how bad not controlling your volunteer wheat can be on the grain crop you plant, even if you plant late.”

Rush said a corner of an irrigation circle where pesticide studies focused on chemical efficacies on wheat curl mite last year was left alone last summer and in July and August the volunteer wheat began to grow.

On the other side of the road, Dr. Qingwu Xue, AgriLife Research plant physiologist in Amarillo, planted a wheat study looking at the impact of different irrigation regimes on different cultivars.

“Because of the proximity of the test this year to the volunteer wheat and all the disease we had out there, a lot of the wheat curl mites carrying wheat streak mosaic virus and other mite-vectored viruses in the volunteer blew downwind into this other research field,” Rush said.

This is exactly what happens to farmers when they don’t control their volunteer wheat, he said.

“So, although it is not something Dr. Xue had intended for his study, it has worked out very well for us, because there are just tremendous differences in the susceptibility of the different cultivars that he has in that test.”

Xue has about 20 different cultivars in the study each planted under three irrigation regimes: 100 percent, 75 percent and 50 percent evapotranspiration – but they are different distances from the source of infection.

Rush said as the mites blow, they land in the 100 percent irrigation plots first and then they have to blow another 1,000 feet until they get to the other areas of the field where the irrigation rate is less.

“So what I think we will see, and we will be able to verify at harvest whether it is true or not, is the far side of the field getting the least pressure of wheat streak mosaic – even at 50 percent irrigation – will end up yielding better than the 100 percent irrigation plots closer to the corner with all the volunteer wheat on the susceptible varieties,” he said.

“There are some wheat cultivars showing high resistance to wheat streak and the wheat curl mite and those in the 100 percent plots are going to have the highest yields, but the ones that are much more susceptible to the disease are going to probably do better in the drier plots further away that don’t have so much disease pressure,” Rush said.

“It’s really remarkable the progress the breeders have made. Some of the wheat lines like TAM 112 and TAM 204 look amazingly good out there, but the proof will come at harvest time.

“I just hope everybody can come out to the field day and actually see this,” Rush said.

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