Web posted
Monday, March 10, 2008
New virus striking wheat plants
By MIKE CORN
Hays Daily News
HAYS, Kan. (AP) -- Outside, the fledgling wheat plants are just starting to stir, taking advantage of the warm days to prepare for a growing spurt as spring approaches.
Inside, wheat breeder Joe Martin is hoping to learn more about a virus that is no more than a few years old, fully identified just two years ago by plant pathologist Dallas Seifers. Martin and Seifers are based at the Kansas State University Agricultural Research Center.
The virus -- Triticum mosaic virus, TriMV for short -- is one to be reckoned with.
It rarely, if ever, appears by itself, generally showing up in conjunction with wheat streak mosaic, itself a virus of concern.
''It acts almost like wheat streak mosaic,'' Martin said. ''Once the two viruses get together, it very quickly kills the plant.''
Both viruses are spread by the wheat curl mite.
On its own, wheat streak has the ability to reduce yields in a field. But wheat varieties have been developed that are resistant to that virus.
When TriMV enters the picture, it has the apparent ability to sidestep a wheat variety's wheat streak resistance.
When that happens, the combination generally kills a wheat field. And in quick order, Martin said, sometimes as short as 30 days.
TriMV was a disease of significance in 2006 when wheat fields inexplicably started dying off. That's when Seifers was able to isolate the disease, differentiating it from wheat streak and a host of other ailments.
Today, Martin and assistant Clayton Seaman were gearing up to process plants that had been exposed to wheat curl mites that came from a field south of Schoenchen. That field ultimately was destroyed and replanted because it had both wheat streak mosaic and TriMV.
The plants, sitting on benches in the center's greenhouse, will be potted, dropped in growth chambers for a couple weeks and then will be tested by Seifers to determine if the disease is present.
Several wheat plants in the greenhouse have gone through similar processes, have tested positive and some have died.
Martin is looking for answers.
''There's a whole lot we don't know,'' Martin said of the disease this morning.
They don't know how much of a threat it might pose to the state's wheat crop or how to stop it, once it has become established.
What he does know is that practices that halt wheat streak also can halt TriMV. Generally, destroying volunteer wheat -- a haven for wheat curl mites -- is the leading method of ensuring wheat streak mosaic doesn't carry into newly planted fields.
With the frequent rains last fall, the use of herbicides was the only surefire way to kill volunteer stands of wheat.
So far, there has been no progress in developing a variety resistant to TriMV.
Martin also knows the virus is deadly.
A field south of Ellis last year, Martin said, was decimated by the disease. Virtually none of it lasted long enough to even head out.
Plants in the field south of Schoenchen already were dying last fall before it was killed off and replanted.
Martin is concerned the mites from the field last fall could have spread to other nearby fields.
Although the virus only was identified two years ago, Martin suspects it could have been around for as long as five years.
That's when he first started seeing wheat streak-resistant varieties dying off in test plots.
What he isn't sure of yet is how much of an economic effect TriMV could have on the state's wheat crop.
''It's going to be important to western Kansas,'' he said, ''because wheat streak is important to western Kansas.''
Many wheat varieties -- such as top varieties Jagger and Jagalene -- have built-in resistance to wheat streak.
''I don't know how widespread it's going to be this year,'' Martin said. ''We have a tough time determining how bad wheat streak will be.''
For now, Martin is running his tests and learning more about the virus.
In the meantime, Martin said he's expecting to see some winterkill, something that hasn't been seen in several years.
But he doesn't expect to see much of it.
Leaf rust, with its severe yield-robbing potential, could be the biggest threat for this year's crop, considering it has the potential for a bumper crop.
''They're a rich man's disease,'' Martin said of the leaf and stripe rusts that threaten wheat fields when moisture is available. ''If you've got a poor crop coming on, it doesn't show up.''
------
Information from: The Hays Daily News, http://www.hdnews.net
|
