Untreated: Left untreated, strawberry crops are susceptible to many soil-borne pests like Verticillium wilt shown in the untreated photo.
Treated: Growing strawberries after pre-plant soil fumigation.
Benefit: Increases yield and eliminates soil-borne pests.
The United States is the world's leading producer and consumer of strawberries, a leading plastic culture crop. The U.S. accounts for 28% of the world supply of strawberries. Soil fumigation has been an essential part of strawberry cultivation since about 1960.
One major source of strawberry yield loss is Verticillium wilt, a disease caused by the fungal pathogen Verticillium dahliae, which attacks the water-conducting tissue of the plant called the xylem. Infected plants wilt and outer leaves dry and turn brown. The diseased plants often collapse during the peak of the first year's growth. Eventually the entire plant wilts and dies. The fungus has been known to remain in the soil for 25 years. Before fumigation became a common practice, growers constantly had to search for new land in order to avoid plant diseases.
Strawberry yields have tripled following the adoption of fumigation and now average about 50,000 lbs/acre in California. In addition, soil fumigation makes land available that had previously been avoided for strawberry cultivation and other plastic culture crops. These are rich, fertile, alluvial lands with long crop histories and fungal infestations. Generally, the increase in strawberry yield is credited to effective control of verticillium wilt with fumigation. USDA has estimated that without the use of soil fumigants, strawberry yield would decline by up to 70%.