We have recently had an outbreak of citrus broad mite (Polyphagotarsonemus latus) in lemons. Broad mites feed on fruit and leaves, preferring young fruit up to about 1 inch (2.5 cm) in diameter that are located on the inside of the canopy or on the inward facing side of outer fruit. Feeding results in scarred tissue that cracks as fruit grows, leaving a characteristic pattern of scars and new tissue. Although most feeding occurs on fruit, broad mites may also feed on young expanding leaves causing them to curl. This cupping and curling of leaves can appear similar to mild damage caused by glyphosate-Roundup applications. Several PCAs have claimed that a variety of pesticides have had a very limited control of the pest
To see if predatory mites could help control the pest, Anna Howell in our office did a laboratory trial to see if the two mites, Amblyseius andersoni and Neoseiulus californicus, would feed on the mite. These are both generalist predators and it was not clear that they would take to the broad mite. Well, they both did, and especially the N. californicus dined on the pest. This is a confined feeding trial where the only thing the predators could feed on was the pest. So the next step is to go out in the field and see if they will knock the pest population down. That’s what we intend to do next week. With a group of PCAs, we’ll be out counting broad mite on lemons for the next several weeks to see if a predatory mite treatment can control the pest.
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