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Ask Your PCA: What is the best way to control citrus thrips?

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Issue Date: May 13, 2020
Chris Boisseranc PCA for Southwest Ag Consulting, Inc., Redlands
Chris Boisseranc

Thrips is one of the most significant pests to citrus because damage can happen very quickly. It is a small bug that lives within the calyx, and it feeds on the young, tender fruit immediately after the flowering stage. Thrips damage the fruit by leaving a permanent "ring scar" that looks like a circle on top of the fruit.

Thrips are a foliage-feeding bug, and they feed on the exterior fruit. The fruit is only susceptible to thrips for about 60 days after flowering. Once the fruit hardens off, thrips are no longer a threat.

Depending on how active the thrips population is, the pest can scar down the side of the fruit, causing substantial damage, and limit the size of the fruit. Untreated, damage can be as high as 10%-20%.

Fruit damaged by thrips is generally marked down to a second or a choice grade rather than the fancy fruit grade.

In Southern California, growers are using different chemistries to treat thrips because of the Asian citrus psyllid. The programs used to target the ACP, particularly pyrethroids, upset the thrips population.

There are predatory mites that feed on thrips, but beneficial insects often don't work fast enough, so chemical treatment is necessary.

In Southern California, treatment is after petal fall—mid-April through mid-June. Chemical treatments are available for both conventional and organic orchards. For conventional groves, there are several chemistries available. This allows for rotation to reduce the risk of resistance building. It's important to treat immediately, because thrips can do 20% or more damage to a grove in three to five days.

In the past, Southern California had one targeted spray application to control thrips when populations were increasing. Currently, there are at least two applications a year.

Permission for use is granted, however, credit must be made to the California Farm Bureau Federation when reprinting this item.

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