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Pests

As growers and pest control advisors plan their arthropod pest management program for 2014, they should consider the consequences of pesticide resistance that would make pest management problematic in the future.

View three presentations concerning threats posed to California avocado groves by new pests and diseases, including laurel wilt disease, fusarium dieback disease, the polyphagous shot hole borer and the Florida redbay ambrosia beetle.

A newly discovered beetle, the polyphagous shot hole borer beetle, is morphologically indistinguishable from the tea shot hole borer, and is believed to vector a new Fusarium sp. leading to Fusarium dieback disease that affects avocado trees.

There are three types of mites that feed on California avocado trees. All three of these mites damage avocado leaves by removing chlorophyll during feeding. Excessive feeding can lead to rapid loss of avocado leaves, effecting the number of avocado fruit on the tree.

Persea mites damage avocado trees by removing chlorophyll from the leaves when feeding. As a result, once 7.5-10% of the leaf surface is damaged, the leaves begin to drop. Because healthy leaves are critical to a healthy avocado tree and crop, persea mite damage can effect avocado growers’ profitability.

There are many ways to manage thrips. Sampling, biological and cultural control, and chemical control combined with employing a knowledgeable pest control advisor to assist with scouting and decision-making, is considered best practice.

What are the ideal and non-ideal grove conditions for avocado thrips? What types of damage can thrips cause?

The major thrips pest attacking California avocados is the avocado thrips, Scirtothrips perseae Nakahara. Originally noticed in 1996, 99% of California avocado acreage is now infested to some degree with this pest.

Avocado tree varieties vary in susceptibility to avocado lace bugs. Hass avocados (a Mexican-Guatemalan hybrid) can be severely damaged by lace bug outbreaks and West Indian x Guatemalan avocado hybrids appear to be particularly resistant to attack.

Adult avocado lace bugs are small-winged insects about 2 mm in length with black bodies, yellow legs and antennae. They live in colonies on the lower surfaces of leaves, often with adults, eggs and nymphs together.

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