Cucurbit Downy Mildew in FL, GA, and SC

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Cucurbit downy mildew, caused by the oomycete Pseudoperonospora cubensis, is a yearly concern for North Carolina cucurbit growers. The disease affects cucurbit crops such as cucumber, watermelon, cantaloupe, pumpkin, and squash, but cucumber is particularly susceptible. The Cucurbit Downy Mildew IPM pipe website has been established to provide an early alert system to cucurbit growers so they can initiate preventive sprays once the disease is found in neighboring states, and they can switch to more aggressive spray programs once the disease is in North Carolina to avoid any crop loss and unnecessary sprays.

This year to date cucurbit downy mildew outbreaks have been reported in Florida (cucumber, squash), Georgia (cucumber, cantaloupe, squash) and South Carolina (cucumber, watermelon). Typically we see downy mildew in North Carolina the first or second week of June, that is next week. Cucurbit growers are advised to initiate preventive sprays immediately, see this disease fact sheet and previous post for control options. Growers are encouraged to read the Southeastern US Vegetable Crop Handbook for the latest fungicide recommendations. When planing your spray program, make sure you alternate fungicide groups of products to avoid generating fungicide-resistant isolates.

It is critical that growers and gardeners are diligent about scouting their crops, and report any confirmed infections to the website. Because the spores of the pathogen can travel from state to state, controlling this disease is a community effort. By being engaged in reporting outbreaks and managing cucurbit downy mildew, we can all help protect our cucurbit vegetable growers.

If you suspect you have an infection, contact your local Extension Agent. They can assist you with diagnosis or may help you send a sample to the Plant Disease and Insect Clinic for confirmation if needed. Once an infection is confirmed, your agent can help you report the outbreak to the websites. The reports are done at the county level, and no specific information needs to be provided other than the host crop and the county.

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