By Lourdes Perez Cordero
If you are a citrus grower in Central Florida, more than likely you have encountered spider mites. These are a common pest of commercial citrus in the state and their characteristic thin webs make them easy to spot in trees.
Spider mites become more abundant between March and June, when the weather conditions are dry, and the relative humidity is low. Even though the population of some species of spider mites usually peaks during spring, they can be present throughout the year.
Different species of spider mites can be found feeding on the midvein section of mature leaves. However, as the population rises, they start moving to other parts of the leaf and can even feed on the developing fruit nearby. Severe infestations can cause mesophyll collapse, reduction of photosynthesis and excessive leaf drop.
The most common species of spider mite that Florida citrus growers may find is the Texas citrus mite, Eutetranychus banksi, followed by the citrus red mite, Panonychus citri. These mostly aggregate on the upper leaf surface. The Texas citrus mite can be recognized by its oval shape and tan body with green to black spots. Similarly, the citrus red mite can become abundant throughout the year, including in nurseries. As the name suggests, this mite is recognized by its red color.
The six-spotted mite, Eotetranychus sexmaculatus, becomes more abundant during winter, and its population tends to drop around June. Unlike the other mites discussed above, six-spotted mites commonly aggregate on the lower leaf surface.
Adult males of some species are easily recognized by their long legs compared to the females. When males are predominant in a given population, there is no need for management since this is an indication that the number of mites is in decline. Management of spider mites will also depend on external factors, such as the temperature, relative humidity and seasonality.
Miticides may provide control over different stages of spider mites, except the eggs. On the other hand, petroleum oil can help control eggs. For more information on spider mites and their management, refer to the 2021-2022 Florida Citrus Production Guide: Rust Mites, Spider Mites, and Other Phytophagous Mites.
Lourdes Perez Cordero is a University of Florida Institute of Food and Agricultural Sciences agriculture and natural resources Extension agent in Highlands County.
This article originally appeared in the November 2021 issue of Citrus from the Ridge to the Valley, the Central Florida citrus Extension newsletter.
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