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Persea Mite

2011 Research

Over the period 23-25 January 2011 residential areas in Tijuana Mexico were surveyed for the presence of avocado trees, and when possible trees were inspected for arthropods associated with trees. Google Earth was used to pre-select six separate residential areas that showed high levels of greenery (i.e., parks, and well maintained residential gardens). In these six areas, 267 residential street blocks were surveyed. From these blocks, a total of 634 properties were inspected from the road. The percentage of street blocks with avocados in pre-selected sections of Tijuana ranged from 23% to 45% of blocks having at least one tree. A total of 80 avocado trees were found from these surveys. Of surveyed properties, 10% or 64 properties had at least one avocado tree. The number of avocados per property ranged from 1 to 5 trees. The GPS coordinates were recorded for each tree and when possible foliage was inspected for avocado pests.

Feeding persea mites can cause extensive foliar damage to avocados and this pest is typically controlled with pesticides. Sustainable pesticide-based control programs must rely on accurate monitoring of persea mite numbers in orchards to determine if pest populations are approaching densities which require control thereby preventing economic damage to trees. Limited applications of pesticides at critical times will significantly delay resistance development by persea mite, save growers money, and promote IPM as a marketing tool for California-grown avocados.

Persea mite was discovered attacking avocados in southern California in 1990. Avocado thrips was found in two isolated avocado groves, one in Orange Co. and the other in Ventura Co., in June 1996. Since then, these have become the two major arthropod pests of avocados in California although populations of each can vary in severity a good deal from year to year. Although it was an unusual year, according to Witney (2009), estimates of direct losses from avocado thrips damage to fruit and control costs for this insect combined to exceed $50 million in 2006.

2010 Research

Persea mite was discovered attacking avocados in southern California in 1990. Avocado thrips was found in two isolated avocado groves, one in Orange Co. and the other in Ventura Co., in June 1996. Since then, these have become the two major arthropod pests of avocados in California although populations of each can vary in severity a good deal from year to year. Although it was an unusual year, according to Witney (2009), estimates of direct losses from avocado thrips damage to fruit and control costs for this insect combined to exceed $50 million in 2006.

2008 Research

It will still be another year or two before new pesticides are available to assist in control of avocado thrips and persea mite. At present, we are depending heavily on the use of abamectin (Agri-Mek and generic abamectins) and there is strong potential for resistance to develop in situations where this material is overused. Once resistance develops, it is likely to spread (via thrips flying around and to some degree, being moved via human traffic), it may or may not revert slowly, and could likely confer cross resistance to the spinosyn class of chemistry (Delegate, Success, and Entrust).

2007 Research

We cannot emphasize enough that it is likely that avocado thrips will develop resistance to abamectin (Agri-Mek and generic abamectins) if this material continues to be heavily relied on as the major means of controlling avocado thrips and especially if it is also used for control of persea mite (and possibly Neohydatothrips burungae if this species were to become problematic in commercial areas).

2006 Research

Our research is aimed at assisting with effective management of avocado thrips and persea mite. We will study how to use available pesticides most effectively, will search for new control materials, hopefully with different modes of action from available materials to reduce the potential for pesticide resistance development, and will evaluate alternative methods of pesticide application and timing of treatments.

 

2005 Research

With as much speed as possible, we hope to improve avocado thrips and persea mite management based on sound scientific research. We will determine how to use available pesticides most effectively, will search for new control materials, hopefully with different modes of action from available materials to reduce the potential for pesticide resistance development, and will evaluate alternative methods of pesticide application and timings of treatments.

 

2004 Research

As fast as possible, we hope to continue to suggest solutions to the avocado thrips problem based on sound scientific research. We will determine how to use available insecticides most effectively, will search for new control materials, hopefully with different modes of action to reduce the potential for pesticide resistance development, and will evaluate alternative methods of pesticide application and timings of treatments.

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