"lambsquarter" - 1 õppematerjal

Sunflower

Diseases Diseases can be a serious problem in a sunflower field. Newer varieties have significantly improved resistance or tolerance, but once a disease occurs, little can be done for control. Verticillium wilt and sclerotinia stalk/head rot are two of the worst diseases. Rust, phoma and downy mildew also can appear. Sclerotinia is hard to avoid, since varietal resistance is minimal and sclerotinia organisms can be built up in a field by soybean, alfalfa, canola, and weeds such as lambsquarter and wild mustard. Harvesting and storage Sunflower is ready to harvest when the back portion of the head turns brown. The seeds actually mature somewhat earlier, but the head will be too wet for efficient harvest until the brown color appears. Timely harvest is important to minimize losses due to birds and late season diseases. Efficient harvest requires a modified grain head on the combine. A standard combine header will cause excessive seed loss to the ground from shattering, so a special