Plan a well balanced soil fertility program based on a soil test. Proper soil pH and adequate amounts of nitrogen, potassium, and phosphorus in proportions required by the crop species will promote healthy plant growth. Avoid high salt accumulation from excessive manure or organic-waste applications. Maintain as high a soil-organic matter content as economically feasible. Control weeds that compete with crop plants for nutrients and moisture.
Weeds can serve as alternate hosts for pathogens thus increasing pathogen populations.
Weed may also result in higher humidity within the plant stand, favoring disease development. Maintain plant vigor by controlling insects. Insects may transmit virus or bacterial diseases or injure plants providing entry points for pathogens. Insect feeding injury can also reduce plant vigor.