To solarize, place clear plastic on top of the moist, clean seed bed for 4 to 6 weeks during the hottest part of the year. Because soil solarization requires a summer fallow season for treatment, it fits in best with a fall-planted crop. Herbicides may be applied before planting or after planting. Foliar-applied herbicides may be utilized after the crop emerges. Layby herbicides are applied to clean cultivated soil at a certain stage of crop development to keep the crop weed-free until harvest.
Most fields require a postplant preemergence application and one layby treatment.
Preplant treatments are used in fields with persistent perennial weed problems. Herbicide selection depends upon the weed species that are expected to occur. Herbicide labels are the best source of information on plantback restrictions. Preplant treatments of metam sodium will destroy most weeds present. Glyphosate has been particularly helpful to control perennial weeds the season before planting.