By Clint Thompson
Biological applications may be Florida blueberry growers’ best management strategy for long-lasting control of mites.
Oscar Liburd, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Professor and Fruit and Vegetable IPM Program leader, said resistance concerns are forcing researchers to consider alternative control measures.
“One of the problems is that if we continue using the miticides that we recommend, after a time, the mites are going to develop resistance. The only way we can really counteract this resistance is by introducing biological control. Mind you, we will still use the miticide but will reduce the amount of miticides we’re going to be using,” Liburd said. “Resistance is a huge problem, especially with mites. Mites reproduce very quickly. The potential for developing resistance is really, really high, because they reproduce so quickly.”
Liburd said growers started complaining about mites four years ago. Florida’s subtropical weather is very conducive for mite development especially if growing under a canopy. Dust also encourages mites.
According to UF/IFAS, multiple species of mites attack southern highbush blueberries. These include the southern red mite, false spider mite or flat mite and blueberry bud mite. Southern red mites can complete a life cycle within two weeks when weather conditions are between 60 degrees Fahrenheit and 86 degrees Fahrenheit. Southern red mites feed on the plant tissues by inserting their mouthparts into the leaf and removing cell contents. This can lead to photosynthesis rate decline.
A life cycle of the flat mites can be completed in less than three weeks. Their damage consists of necrotic brown spots on the leaves, stem browning, gall formation, brownish patches on the fruit, defoliation and dieback.
Liburd said biological testing is ongoing. They are researching three predatory mites. They hope to have recommendations in the spring.