Photo courtesy of Fundecitrus
Brazilian research organization Fundecitrus has for several years studied the use of kaolin for psyllids and the citrus greening they spread, as well as for citrus canker.
Kaolin is a natural mineral composed mainly of aluminum silicate. In the kaolin experiments conducted by Fundecitrus, the commercial product Surround WP was used.
PSYLLIDS AND GREENING
The Fundecitrus studies show that spraying kaolin on citrus leaves forms a white film that hinders the visual identification of the plant by the citrus psyllid. The psyllid primarily relies on vision to locate plants for reproduction and feeding.
“By altering the plant’s appearance, kaolin confuses the insect and directly interferes with its host-selection behavior — in this case, citrus plants,” said Fundecitrus researcher Marcelo Miranda. “If it cannot land to feed, it is also unable to transfer the disease-causing bacteria to the healthy plant and lay its eggs.”
Miranda said research results have demonstrated the potential of kaolin as a complementary tool to chemicals that can be used in the management of psyllids in large commercial areas.
See a University of Florida Institute of Food and Agricultural Sciences article about the combined use of essential oils and kaolin to control psyllids.
CITRUS CANKER
In greenhouse experiments conducted by Fundecitrus, kaolin reduced citrus canker disease severity by 80%, a result comparable to that of copper, the main control product currently used.
Fundecitrus researcher Eduardo Gorayeb said kaolin forms a coating on the plant that may act as a physical barrier against the bacterium that causes citrus canker. It also reduced leaf drying time by up to 50% after simulated rainfall, thereby shortening the time window favorable for infection, Gorayeb added.
Although kaolin is more costly than copper, its use for psyllid management may provide additional advantages to growers.
“Kaolin can help extend the interval between copper applications for citrus canker, especially in areas with lower disease propensity, thereby reducing the total amount of copper applied in groves,” Gorayeb said.
Read more on Fundecitrus kaolin research here.
Source: Fundecitrus
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