Concentrated straw and chaff also provide a favorable environment for several soilborne diseases of cereals, including Pythium and Rhizoctonia. Poor crop stands and low plant vigor as a result of disease reduce competition against weeds in those areas as well as lower crop yield potential. There is a potential for immobilization of plant nutrients during microbial decomposition of the concentrated residue. This could reduce the available nutrient supply for the crop, particularly early in the season. Nutrient deficiencies would result in reduced crop vigor and competitive ability.
Concentrated residue provides a food source and cover for rodents.
Rodent damage reduces crop stands and consequently reduces competition against weeds. Early and Throughout When a summer fallow year follows harvest, the next weed control consideration in the conservation tillage system is when to initiate the chemical or chemical-tillage fallow portion of the system. Ogg points out that, in the Northwest, herbicide applications on fallow maybe made in the fall, late winter or spring, depending on weather conditions and weed species present. Ogg points out that soil-active herbicides are generally most effective when applied in the fall. Foliar-active herbicides can be applied in the fall or in the spring.