As if the epic drought wasn’t bad enough, one university researcher is saying pest issues in California citrus groves this year could be particularly bad.

University of California citrus research specialist Elizabeth Grafton-Cardwell studies pests at the Lindcove Research and Extension Center in Central California where she is also the station director. Grafton-Cardwell recently told growers that she expects a particularly tough year for mites and thrips.

“I’m not sure whether the freeze or the drought will be a major player, but watch your thrips populations,” Grafton-Cardwell said.

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The Citrus Thrip is just one of several pests Grafton-Cardwell believes could be troublesome this year. While severe freeze damage will cause citrus leaves to fall to the ground – the leaves are where thrips overwinter as an egg – “drought conditions are when we see the highest populations of thrips,” she said.

“When we have wet years that seems to suppress the pupae from forming,” she continued.

On the other hand Bean Thrips, which live as adults inside Navel oranges, could be less of an issue this year because of the drought and the freeze. One likely reason is weed populations that harbor the Bean Thrip prior to moving into citrus was lower.

Grafton-Cardwell said researchers saw “some interesting situations in mandarins recently” related to the Western Flower Thrip. “We don’t normally think of it as a pest at all.” Because of the impacts of the freeze to mandarins, she said they saw Western Flower Thrips living between the fruit rind and doing some damage to the fruit.

“We don’t normally see that,” she said.

Grafton-Cardwell also expects mite populations – such as the Citrus Red Mite and the Two-Spotted Spider Mite – to be troublesome this year as the effects of the freeze and drought combine to make conditions ripe for the pest.

“Stressed trees have more mites,” she said.