Red Kaolin Clay Reduces Psyllid Attacks

Kaolin clay, especially when dyed red, is great for enhancing tree growth and discouraging infestation by psyllids.

With each passing year, researchers are making more advances in the fight against citrus greening. This devastating citrus disease has had a major impact on Florida’s agricultural industry, which is why it is so important to find ways to mitigate the damage.

While there is no “silver bullet” cure for greening, there are many techniques that growers can use to slow the disease and help their trees become more resistant to it. Dr. Christopher Vincent, Assistant Professor of Horticultural Sciences with the University of Florida’s IFAS Citrus Research and Education Center, has been investigating the use of kaolin clay to deter the psyllids that carry the disease.

There are a number of different brands of white kaolin clay available on the market. Only one is approved for psyllid control — Surround by NovaSource. Most of the kaolin is sold as a growth enhancer. Kaolin clay improves tree growth by improving light conditions for the plant. This same mechanism makes the citrus trees diffcult for psyllids to perceive by disrupting the wavelengths of light that psyllids use to identify their food source.

Some of the limitations of kaolin clay are that during high rush periods it does not adhere well to leaves, and it is easily washed off by rain. Vincent’s research has found that red-dyed kaolin clay is more effective than white clay both at enhancing growth in citrus trees and inhibiting psyllid infestation. An additional benefit of red-dyed clay is that some of the dye products available will make the clay adhere better to the leaves.

Kaolin clay does not clog up the stomata of the leaves, and is effective at managing leaf temperatures. Due to its light refraction properties, it can reduce sunburn and increase photosynthesis throughout the canopy. Kaolin is non-toxic, inert, and widely accessible. Standard spray equipment can be used to apply it. Therefore, it is a safe substance for citrus growers to use to enhance growth and deter psyllids in their groves.

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