Welcome Idaho rains also raise crop disease risk

Wheat in Aberdeen, Idaho, begins to yellow due to recent frost damage amid a stretch of cool, moist weather. University of Idaho Extension cereals pathologist Juliet Marshall believes the conditions could heighten disease pressure, though the rain has been otherwise welcome following a dry spring.

ABERDEEN, Idaho — Crop experts warn a May shift toward cool and wet weather that’s dramatically improved the irrigation outlook has also heightened the risk of disease and created other challenges for Southern Idaho farmers.

The recent string of storms dumped 4 to 6 inches of rain throughout Southern and Eastern Idaho as of May 26, with more storms in the forecast, said Ron Abramovich, water supply specialist with USDA’s Natural Resources Conservation Service.

Though the rain has been timely following three months of dry and unseasonably warm weather, it’s created ideal conditions for stripe rust to spread in wheat, said University of Idaho Extension cereals pathologist Juliet Marshall. In barley, Marshall said scald, net blotch and the spot form of net blotch have been developing in the cool, moist conditions.

She said stripe rust has been reported in Weiser, Parma, Twin Falls, Hansen and at the Tetonia Research and Extension Center, and should soon begin surfacing in Eastern Idaho fields.

She’s advised grain growers to spray full rates of fungicides with their herbicides. She said a second application of fungicides may be necessary, especially on spring grains, and growers should carefully scout their fields.

“(Stripe rust) definitely has great conditions for a flareup,” Marshall said. “We’re seeing problems everywhere with some of the diseases.”

Cooler temperatures have also taken a toll on crops. Throughout the Aberdeen area, Marshall has seen widespread yellowing in barley, which she attributes to damage caused by frost on May 10.

Declo grower Mark Darrington has seen stripe rust spores in his sage brush, but his wheat fields have thus far been protected by fungicides he applied with his herbicides. He’s waiting to see if a second fungicide application is necessary.

In potatoes, Mike Larsen, manager with 4D Farms in Rupert, said weeds are emerging where rains have diluted herbicides. He’s concerned herbicides may have leached into the spud root zone, which could potentially cause crop damage. Furthermore, his corn planting has fallen behind schedule.

Aberdeen grower Kim Whalen believes moist conditions may have elevated the risk of rhizoctonia in spuds and sugar beets. Jerome County grower Randy Grant said the rains have replenished soil moisture, but he’s also got 1,000 acres of hay past its prime and awaiting cutting and dry beans that need to be planted, once dry weather returns.

In Raft River, some of the moisture fell as hail, damaging patches of sugar beets in grower Mike Wheeler’s fields. He said hail forced one of his neighbors to replant some of his beet acres.

Nonetheless, the growers agree they’re better off for having the rain.

“The rain was a huge blessing to water users, absolutely a huge, huge blessing,” Darrington said. “The question is, when does a blessing become a curse?”

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