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Researcher offers tips for legume diseases




By MATTHEW WEAVER


Capital Press


MOSCOW, Idaho -- A Pacific Northwest researcher is keeping an eye out for several potential grain legume diseases in the coming year.


Weidong Chen, USDA Agricultural Research Service plant pathologist, found a widespread yellowing of chickpeas in 2012 was most likely bean leaf roll virus and pea enation mosaic virus.


Aphids transmit the viruses, which do not spread from plant to plant.


Aphid control methods are not available for chickpea producers, Chen said.


"There's nothing we can do," he said, noting resistant varieties would help, but aren't expected. He will continue to keep an eye on the situation, he said.


Chen said growers first noticed the yellowing in 2010, then it resurfaced in 2012.


The yellowing occurred all over the Palouse, with severity highest in southern fields, likely as aphids entered the region from the southwest.


Chen also found stemphylium blight on two lentil fields south of Moscow, Idaho, in 2012.


The fungus has had a devastating effect in Bangladesh and India and has been observed in Canada and North Dakota.


The blight is a warm-weather disease, 75 degrees Fahrenheit or more, that requires moisture to progress.


Chen said that fungus spores began on the tips of the lower leaves of the lentil plant, but healthy green leaves remained on top, either emerging as new growth or because the fungus missed the moisture period.


The USDA ARS lentil variety Morena showed the most susceptibility to the blight. But Chen did not find the fungus with further testing on the seeds harvested from the field in question.


Infected seeds did not transfer the disease onto the seedlings, Chen said.


"The seed we harvested from that field is still good seed," he said.


It's not sure whether the disease will occur again, Chen said. Morena grew in other fields and turned out all right.


Chen recommends growers use one application of fungicide if they see early signs of the disease around late June or early July. But that seems unlikely, since it has not been a large problem, he said.


"I'm reluctant to say 'You should spray,' because you may not have the disease," he said.


If farmers choose to plant the lentil Morena, they should use clean lentil seeds and their normal seed treatments and rotate their fields with a cereal crop.


Most lentil cultivars are resistant to the blight, Chen said.


Chen recently provided an update on his research during the Western Pea and Lentil Growers association conference in Moscow, Idaho.




Information


Contact Chen at 509-335--9178 or weidong.chen@ars.usda.gov





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