After 1 year, Cook is hopeful that the test will help accelerate the selection and release of Pythium -resistant cereal varieties. Impact of Pythium Research by Cook and associates over the past 12 years has shown that Pythium root rot can be a major production constraint for wheat and barley in Northwest cropland receiving at least 16 inches annual precipitation. Where Pythium populations in the soil were experimentally reduced or nearly eliminated, wheat yield typically increased 15 to 20 percent and sometimes up to 50 percent.
Pythium is a parasitic water-mold fungus favored by cool, wet conditions.
Consequently, late-seeded winter wheat is most severely impacted. Early-seeded spring wheat and spring barley can also be damaged if cool, wet soil conditions prevail after planting. Pythium has been shown to limit yields regardless of the tillage system used. However, since this pathogen is favored by cool wet soils, and it benefits from chaff and straw which serves as a food source, Pythiwn can be an important problem under tillage systems with larger amounts of surface residue. Where the Pythium population was experimentally reduced, wheat yields under no-till have equaled or exceeded yields under clean conventional tillage.