Chemical Alternatives to Methyl Bromide in Spanish Strawberry Nurseries

Strawberry runners are a high-value cash crop in Spain that requires vigorous transplants free of pathogens. Preplant soil fumigation with methyl bromide, or with mixtures of methyl bromide and chloropicrin, is a standard practice for controlling soilborne diseases. Soil fumigants chloropicrin, 1,3-dichloropropene, dazomet, metam-sodium, metam potassium, and dimethyl disulfide were evaluated in combination with different plastic films as alternatives for methyl bromide soil fumigation of strawberry nurseries. The studies were conducted over a 4-year period, with fumigant applications prior to planting. Verticillium wilt (caused by Verticillium spp.) and crown rot (caused by Phytophthora cactorum) were the main diseases. Chloropicrin, 1,3-dichloropropene, and dazomet compared well with methyl bromide fumigation for control of strawberry nursery diseases. Furthermore, 1,3-dichloropropene and methyl bromide, applied at 50% rate under virtually impermeable film, provided effective disease control in strawberry nurseries. Fumigant effects on fungal soil populations are discussed.