Stripe rust report details 2016 yield loss predictions

A Washington State University research plant pathologist last week released the first stripe rust update for susceptible crops in 2016.

Xianmeng Chen released the report Jan. 11, stating that the early forecast for highly susceptible winter wheat varieties indicates “about 30 percent yield loss, in the middle of (the) moderate epidemic range.”

Stripe rust is a plant disease in which “chlorotic patches or stripes on leaves” appear “followed by rust sporulation, forming tiny yellow to orange colored rust pustules called uredia,” according to the USDA website. It is typically found in wheat grown in cooler environments.

Chen said that based on this data, “currently grown varieties would have zero to 15 percent yield loss, depending on the level of susceptibility.”

Chen told the Gazette that this prediction is based on the temperatures and moisture levels in November and December and that this report “is most applicable to the Palouse area.”

“Most of the varieties will be much lower,” Chen told the Gazette. “We will do another forecast in March, which is usually more accurate than the early predicted because we use the weather conditions throughout the entire winter period.”

Chen said that moisture is good for the crops around here, but snow pack can create a problem when it comes to the stripe rust.

“Moisture does not influence the rust in the winter, but the snow cover actually helps the rust to develop,” he said.

Chen added that normal weather conditions can make the early forecast predictions lower.

“But some people say that the Palouse does not have normal conditions because the weather changes every year,” he said.

Noting the hot and dry conditions for the 2015 crop season, Chen said that “last year, the weather was not good for wheat production,” but it did help to keep the rust levels down.

“When the weather is good for production, there will also be higher rust levels,” he said.

Chen said moisture throughout the remainder of the growing season will be important to determining how stripe rust might affect the susceptible varieties.

“Throughout the remaining growing season, the moisture is more important,” he said.

Chen noted in his report that on Nov. 10, 2015, winter wheat fields in Whitman County were checked, and no rust was observed at that time, but that could change based on weather patterns.

“If the weather conditions become more favorable for the disease, the disease will be more severe than predicted,” he said.

Chen said the next forecast will be completed in early March.