Surprise! Your Strawberries are Moldy

Grey mold on strawberries

Gray mold on strawberries

Consumers sometimes buy picture-perfect strawberries only to find them covered in mold after a few days. The cause: the gray mold fungus which infects the berries in the field but which remains symptomless until the fruit ripens. The fungus produces a velvety gray growth on the surface of the berry. Gray mold spreads in shipping containers when the fungus grows from a rotting berry to an adjacent healthy fruit. 100% of US strawberry acres are estimated to be infected with the gray mold fungus. Widespread infections are prevented with fungicide treatments.

“Gray mold is one of the most economically important diseases of cultivated strawberry (Fragaria × ananassa), and a significant threat to the United States’ $2.4 billion strawberry crop… Crop losses resulting from gray mold disease are especially severe under moist weather conditions, and occur not only during the crop growing season but also after harvest and during storage and transit.

The control of gray mold in commercial strawberry fields is largely dependent on the application of fungicides during bloom and fruit maturation.”

Authors: Grabke, A., et al.
Affiliation: Clemson University.
Title: Fenhexamid resistance in Botrytis cinerea from strawberry fields in the Carolinas is associated with four target gene mutations.
Source: Plant Disease. 2013. 97[2]:271-276.

To Remain Viable, California Strawberry Growers will need to use Fumigants for Years to Come

Strawberry Production: California

Strawberry Production: California

California is the top strawberry growing state producing 2-3 billion pounds per year. California accounts for 20% of the world’s production of strawberries. Since about 1965, approximately 90% of strawberry land in California has been fumigated before each crop is planted. Statewide average strawberry yields tripled following the adoption of fumigation. Generally, the increase in strawberry yield is credited to effective control of the soilborne fungal disease, verticillium wilt, which attacks the water-conducting tissue of the plant. In recent years, the use of fumigants in California has been under intense regulatory review with a phaseout of methyl bromide and use restrictions which could include expanded buffer zones in strawberry fields where fumigation will not be permitted. A recent working group in California assessed the status of nonfumigant alternatives……

“Owing to potentially devastating soilborne pests, strawberry growers have relied on soil fumigation treatments for many years.

Director Brian Leahy of the California Department of Pesticide Regulation convened in April 2012 a working group of industry and scientific leaders to develop an action plan of research priorities for developing cost-effective management tools and practices for soilborne pests of strawberries in the absence of conventional fumigants.

The Working Group recognized that over the last 20 years, many studies focused on breeding disease-resistant plants and testing soil treatments such as anaerobic soil disinfestation, biopesticides, biofumigants, soilless substrate, steam, and solarization.

Yet to be done is testing combinations of alternatives in extensive field trials and on-farm demonstrations.

Full implementation of the action plan will require a major commitment of time and resources by a broad range of groups in the private and public sectors, such as researchers, funding institutions, growers, grower organizations, farmworker advocates, community and environmental organizations, and consumers.

Even with full commitment to implement this action plan, the strawberry industry will need to continue its use of fumigants for years to remain viable in California.”

Title: Nonfumigant strawberry production working group action plan
Source: California DPR. April 2013. Available at: http://www.cdpr.ca.gov/docs/pestmgt/strawberry/work_group.htm