Mild, dry winter poses huge challenges for Idaho farmers

MOSCOW, Idaho — Idaho farmers face a multitude of production challenges — including heavy weed and pest pressure, rampant crop diseases, frost damage and water shortages — following a historically mild and dry winter.

In southern and eastern Idaho, weeds and insects withstood one of the warmest winters on record.

Furthermore, the lack of winter moisture has forced many growers to shift toward planting low-water crops — and, in some cases, leaving entire fields unplanted.

Eastern Idaho

Juliet Marshall, a University of Idaho Extension specialist in cereals and associate director of the Idaho Agricultural Experiment Station, saw unusually large aphid numbers in fields throughout eastern Idaho at planting time, setting the stage for potential insect-related crop damage and the spread of insect-borne diseases. Overwintering conditions allowed insect and mite populations to thrive.

“This spring, we saw fields where the mite pressure was so high that the grower opted for chemical control, which is unusual in irrigated winter grain,” Marshall said.

Many winter cereal fields are showing symptoms of virus infection. James Woodhall, an Extension specialist in plant pathology, has confirmed higher incidences of cereal viruses spread by aphids, including strains of barley yellow dwarf virus that aren’t normally found in the region.

Marshall also worries that an abundance of aphids feeding on grain heads could create a sticky residue capable of gumming up harvesting equipment.

As with weeds, fall-planted wheat and barley never went fully dormant during the winter, pushing crop development more than a month ahead of the usual schedule. Some fall-planted barley crops that normally develop grain heads in late May started producing heads in mid-April. Plant heights have been stunted because of premature heading from drought stress, and most plants produced fewer seed-bearing stems, known as tillers, than normal.

Marshall suspects crop tillers that developed early were susceptible to mid-April freezes, and she’s heard reports of frost damage to winter barley heads in eastern Idaho. Marshall worries a black, powdery fungal growth, known as sooty mold, will infect frost-damaged tillers, even if plants recover and produce secondary tillers.

The lack of ample winter precipitation has left most of the state with insufficient soil moisture and snowpack. In eastern Idaho, the irrigation outlook is so dismal, Marshall has seen fields where growers chose to kill their crops with herbicide in the spring rather than continue raising them. She also knows of a farmer north of Idaho Falls who left nearly 2,000 acres unplanted due to water constraints.

“I just hope everybody has good crop insurance,” Marshall said. “I don’t know how else everybody is going to make ends meet this year.”

Kasia Duellman, an Extension seed potato pathologist, predicts more volunteer potatoes will emerge this year, which could increase growers’ problems with two challenging diseases affecting potato production — potato virus Y (PVY), which primarily affects seed potatoes aiming to meet certification requirements, and late blight, a fungal disease that occurs sporadically in Idaho and was responsible for the devastating Irish potato famine from 1845-1850.

“These volunteers may serve as reservoirs for PVY, potentially increasing the risk of a high PVY disease pressure year for the seed potato grower,” Duellman said. “Another risk with volunteer potatoes is the possibility that the over-wintered tubers harbored the notorious potato late blight pathogen, Phytophthora infestans.”

Treasure Valley

At U of I’s Parma Research and Extension Center in the Treasure Valley, Woodhall has received many requests to test plant tissue samples from throughout southern Idaho for barley yellow dwarf virus, and far more of them have tested positive for the disease than normal. Testing helps farmers rule out other crop stressors that can cause symptoms similar to those of barley yellow dwarf, such as poor fertility and various environmental conditions.

Soilborne diseases can also flare following mild winters, potentially affecting the whole gamut of Idaho crops.

“It’s still too early to see what impact a warmer winter will have on soilborne diseases, but theoretically with a warmer winter you’re going to get less killing of soilborne fungi,” Woodhall said.

Magic Valley

Cool and windy early season conditions were also ideal for the development of a fungal disease that can devastate cereal production, known as stripe rust. While it has not been confirmed in grain crops, other strains of stripe rust have been found in grassy weeds in the Magic Valley by Extension Educator Steve Hines, Jerome County.

Furthermore, Hines, who specializes in crops, has received confirmation from insurance adjusters that several hundred acres of sugar beets were killed by frost in the Cassia County area. Many other sugar beet farmers in the Magic Valley were spared from frost damage because they delayed planting until they had access to irrigation water, concerned about a lack of soil moisture.

Hines has also heard concerns about the outlook for Magic Valley grain that developed well ahead of schedule and was then exposed to frost. He’s encouraged that alfalfa that broke dormancy much too early still appears to be in good condition.

UI Extension plans to post online resources for farmers facing extreme water shortages.

Magic Valley irrigators who get their water from Salmon Falls Creek Reservoir will have to cope with just a 10- to 19-day water supply this year. Farmers who draw water from the Big Wood River system will also face extreme water shortages.

“There’s going to be a lot of ground out there that doesn’t get planted,” Hines said.

Northern Idaho

In northern Idaho, Doug Finkelnburg, an area Extension educator in cropping systems, has fielded questions from farmers about weed problems and volunteer canola. The region’s fall-planted wheat has progressed well ahead of schedule, and crop foliage has grown to cover spaces between rows earlier than normal, blocking herbicide spray from reaching weeds that have grown vigorously beneath the canopy.

In response to growers’ concerns, Finkelnburg and his team plan to research whether volunteer canola that has bloomed could be a potential vector for two damaging diseases of winter canola crops — blackleg fungus and sclerotinia fungus.

MEDIA NOTE: A full list of water and drought experts who are available to speak to the media can be found here.

Media contact

Juliet Marshall
Associate director of Idaho Agricultural Experiment Station, professor and Extension specialist in cereals
208-529-8376
jmarshall@uiidaho.edu 

Steven Hines
UI Extension educator, Jerome County
208-324-7578
shines@uidaho.edu 

Doug Finkelnburg
Area Extension educator in cropping systems
208-799-3096
dougf@uidaho.edu 

James Woodhall
Extension specialist in plant pathology
208-722-6701
jwoodhall@uidaho.edu 

Kasia Duellman
Extension specialist in plant pathology
208-529-8376
kduellman@uidaho.edu