University of Florida multi-county citrus Extension agent Chris Oswalt discussed fungal disease management in the April Central Florida citrus Extension newsletter. Here is a summary:
In Florida, fruit fungal diseases that are oftentimes problematic in the early spring are melanose, scab and alternaria brown spot, along with citrus canker. In the summer period, greasy spot is more of a problem, along with lingering canker infections that last through the growing season into the fall.
For optimal control of these early fungal diseases, it is important to schedule applications of fungicides at the proper time. Table 1 outlines a fruit fungal management program developed from the Florida Citrus Production Guide. This table lists the susceptibility of specific varieties to fungal diseases and the timing of fungicide applications.
Scab affects fresh grapefruit, tangerines and tangerine hybrids, while alternaria is limited to mostly fresh tangerines and tangerine hybrids, including Minneola tangelos.
Melanose can affect all fresh citrus varieties. The severity will be related to the amount of recently killed twigs in the tree canopy.
Citrus canker affects all varieties (fresh and processed). If your grove has canker, it is an ever-present threat during the growing season, particularly during late summer with uncontrolled citrus leafminer populations.
Greasy spot rind blotch affects predominately fresh grapefruit, although all varieties (fresh and processed) are susceptible to foliar infection.
Find specific guidance on the recommended fungicides for use on these diseases in the 2020-21 Florida Citrus Production Guide.
Source: University of Florida Institute of Food and Agricultural Sciences
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