The Best Fungicides to Spray on Peach Tree Blooms in Louisiana

Considerations

• Although agricultural fungicides might be mixed on site, fungicides for home use are typically pre-mixed and packaged in applicators. Top fungicide recommendations for Louisiana home orchards contain captan, chlorothalonil, myclobutanil and sulfur, which is also available as a dusting powder. Fungicides are largely preventative, meaning the spray must be applied before fungal spores are present rather than once fruit or plants have been infected. Good sanitation, ample water, proper nutrients. open spacing to ensure good air circulation and disinfecting pruning equipment help control fungal diseases, too.

Common Diseases

• Peaches (Prunus persica) grow from U.S. Department of Agriculture plant hardiness zone 5b through 8b, which includes about two-thirds of Louisiana. Fungal diseases pose a special problem in the state’s warm, humid weather. The most common diseases in the Pelican State are brown rot (Monilinia fructicola) and peach scab (Cladosporium carpophilum). Brown rot appears as a dark spot on the fruit and spreads, eventually covering the fruit, causing it to shrivel, or “mummify.” Brown rot spores overwinter in mummified fruit. Peach scab begins as green or black spots near the stem on the fruit. The fungus spreads to cover the peach and leaves.

Sprays

• Brown rot occurs most frequently in wet years and attacks spring blossoms. Fruit becomes most vulnerable as it ripens, two to three weeks before harvest begins. Captan and chlorothalonil are recommended for use during blossoming. Captan and sulfur are favored for late season spraying. Captan comes in a 50 percent solution, chlorothalonil in a 29.6 percent preparation and sulfur sprays are sold in 90 percent solutions and dusting powder. Peach scab arrives every year, so apply chlorothalonil preceding bud break. Thereafter, captan and sulfur sprays are more effective.

Other Problems

• Some types of peaches are vulnerable to leaf curl, which occurs during wet, cool weather as buds emerge early in spring. Chlorothalonil is used only on susceptible varieties. Fungicides tend to provide continuing leaf curl protection from year to year. Rhizopus (Rhizopus stolonifer) and Gilbertella rot (Gilbertella persicaria) occur when fruit is allowed to rot on trees or on the ground and are addressed by careful sanitation.