Objective #5: Wind Erosion and PM10 Emission Control Methods Title: Agronomic Comparison of Pacific Northwest Winter Wheat Varieties and Advanced Breeding Lines in Early Planted Tilled Fallow versus Late- Planted Chemical Fallow

Sixty percent of Washington’s winter wheat production area receives only 150 to 300 mm annual precipitation (Hasslen and McCall, 1995). In this 3.7 million acre dryland area, stand establishment is the most important single factor affecting grain yield (Bolton, 1983). Through the practice of summer fallow, growers can generally achieve adequate stands of winter wheat (Triticum aestivum L.) by sowing in late August or early September into soil moisture accumulated from the previous winter. However, this practice leads to significant wind erosion. The alternative is to chemical fallow, but this production system leaves little moisture in the ground, requiring the producer to delay planting until significant moisture is accumulated through rainfall, usually mid to late October. The objective of this study is to determine which wheat cultivars are best suited for late planting into chemical fallow conditions compared to the conventional tilled fallow systems. When comparisons are made between market classes, the soft white and club classes are the most productive. Many cultivars show cross-over interactions between systems and years, usually indicative of emergence problems. Lines which can’t emerge under the tilled system can emerge under the chemical fallow system. The tilled fallow system consistently has higher grain yield than the chemical fallow system. This is due to the delay in plant growth and heading (16 days later) o