See the UF/IFAS Tip of the week on planning for greasy spot and melanose, two fungal diseases affecting citrus trees.
Florida citrus growers have their hands full with citrus greening, but it is not the only disease affecting citrus in The Sunshine State. According to the U/IFAS Tip of the Week, published in a Citrus Industry article, greasy spot and melanose are two fungal diseases that Florida citrus growers need to plan for. See excerpts of the UF/IFAS recommendations below.
Greasy Spot and Melanose Planning
The Tip of the Week maintains that both fungal diseases are a bigger concern for fresh fruit growers, but the two diseases can affect trees for processing as well.
The article outlines the following:
Greasy Spot. “Z. citri-griseum is exposed on the surface of the leaves and fruit for several months prior to tissue infection through the stomatal chambers. This vulnerable stage is targeted with spray applications.
For Valencias destined for the processing market, a single application of either spray oil at 5 to 10 gallons per acre or a combination copper and spray oil (2 pounds per acre and 5 gallons per acre) applied over the two-week period from mid-May to June should give sufficient control to avoid defoliation.” However, “Early and mid-season oranges are more susceptible and may require two applications.”
Melanose. “Melanose is primarily a concern for fresh fruit because it can scar the fruit peel…While the fungus moves with rain, the spores are produced and remain viable on the twigs for up to a month in dry periods…the first application for melanose is usually in mid-to-late April or when fruit are ¼- to ½-inch. Copper, the most economical product, should be applied every 21 days at 2 pounds per acre until the fruit are no longer susceptible.”
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