by LUIS RODRIGUEZ
Strawberries are among the most popular fruit crops. Unfortunately, a fungal disease known as Powdery Mildew can occur in most places where strawberries are grown.
What Is Powdery Mildew?
Powdery Mildew is a fungal disease that affects strawberry leaves, flowers, and fruit. Early signs on leaves include small white patches on the leaf’s underside, which can grow and look powdery on certain varieties. In certain cultivars, yellow or reddish-brown spots may form instead. Heavily infected leaves may curl up, and small black structures can appear as the fungus matures. The fungus also damages flowers, leading to deformities or failed fruit. It can even affect older fruit, covering the seeds in a fuzzy growth. Generally, Powdery Mildew can reduce fruit quality and crop yields.
Powdery Mildew only affects living tissue. They can spread to plants through conidia (spores) in the wind. The most common source of infection in Florida is nursery-infected transplants brought to the state. Temperatures between 60 and 80 degrees Fahrenheit, rain, dew, overhead irrigation, and over-irrigation can promote the growth of this fungus. In Central Florida, the disease is more common during November and December when these conditions are met. Normally January and early February the fungus is not as common but it may reappear in late February and March when the temperature starts rising again.
Control OF Powdery Mildew
If available, growers can buy disease-free transplants to help them mitigate Powdery Mildew. However, this will not protect the crops from conidia blown by the wind from nearby farms that may be infected.
The use of resistance cultivars could also help to control Powdery Mildew. Cultivars such as Florida Radiance and Florida Brilliance show signs of being moderately resistant. On the other hand, cultivars such as Sensation and Florida Beauty show signs of being highly susceptible to the fungus. All growers must implement a monitoring program where they can look for signs of Powdery Mildew, especially growers using susceptible cultivars.
Preventive fungicides can help mitigate Powdery Mildew. Growers need to read the label instructions to apply these products effectively and rotate them accordingly to avoid creating resistance. To find a list of Available fungicides that can control Powdery Mildew please read the following “Ask IFAS” publication called: Powdery Mildew of Strawberry.
For more information about Florida Strawberry diseases read the “ASK IFAS” Publication: Common Strawberry Diseases in Florida.
For information on Florida Strawberry production click here.
Disclaimer: The information presented in this article was based on the “Ask IFAS” publication: Powdery Mildew of Strawberry.
Luis Rodriguez is the Polk County Small Farms and Pesticide Education Extension Agent. You can reach him at lrodriguezrosado@ufl.edu
