Disease Update 12-14-2016

To: Oregon Wheat Growers and Industry Reps
From: Mike Flowers, Chris Mundt, and Christina Hagerty; OSU

RE: Disease Update

Eastern Oregon:
Good seeding conditions and adequate moisture has the crop off to a good start. These conditions are also favorable for several plant diseases. Early fall plantings are particularly susceptible.

Active stripe rust has been found in portions of eastern Oregon this fall. Fall treatments for stripe rust control are generally not recommended (there are rare instances where a highly susceptible variety with a heavy fall infection of stripe rust would benefit from a fall/early winter treatment). Cold weather will reduce and may kill stripe rust. Snow cover will help stripe rust survive the cold temperatures.

Given the conditions, growers in eastern Oregon should scout their fields when temperatures warm and the crop starts spring growth. Growers should pay particular attention to wheat varieties that are susceptible to stripe rust. Growers should treat their fields if stripe rust is found and/or they have a susceptible variety and stripe rust is found in their surrounding area. The most effective treatment at that time is to tank mix a fungicide with your spring herbicide application. The least expensive, registered chemical will usually be adequate at this time of year.

Growers should also be aware that conditions are favorable for several other wheat diseases. These include strawbreaker foot rot, Cephalosporium stripe, soil borne wheat mosaic virus, and barley yellow dwarf virus. Growers should be on the lookout for symptoms of these diseases as they scout their fields.

Western Oregon:
Fall rains delayed wheat planting in many areas of western Oregon. This combined with a low stripe rust year in 2016 may indicate that stripe rust will arrive in western Oregon later than in the past several years. However, growers should scout their fields as temperatures warm and spring growth starts. Growers should be prepared to treat fields for stripe rust as necessary. Tank mixing a fungicide with your spring herbicide application is a very effective way to control early season stripe rust.

Septoria may also be influenced by the delayed wheat plantings. Most wheat was planted after the fall rains and may have avoided much of the fall Septoria infection. Spring Septoria infections are expected. Growers should scout their fields and be prepared to treat for Septoria. The most effective Septoria control is a fungicide application at flag leaf emergence. Earlier fungicide applications are not recommended for Septoria control.