May 6 , 2003

This is the first of numerous spider mite news letters for the summer of 2003. We would have published a newsletter before but the unusually cool and wet weather in the San Joaquin Valley has delayed spider mite season. There are spider mites (Two Spotted) in some places in the valley but as of today the mite population is quite low. With the longer days and the sure to come warmer temperatures Spider Mites will make their presence known before the season is finished.

A Grower and Pest Control Advisor (PCA) now faces decisions about how they can integrate Predatory Mites (Galendromus occidentalis) into their pest management program. We have found that the intense spider mite pressure in the warmer inland valley areas of California usually requires Predatory Mites usually be used in conjunction with chemical miticides or oil. There are exceptions to this statement but a week of 100 F plus weather at the end of this month can raise spider mite populations to astronomical numbers almost overnight. That has happened in this author’s experience.

Preventative (Ovidical) Miticides and Predatory Mites:

There are a number of good “preventative” miticides on the market. Products like Abamectin, Clofentezine and others that act primarily on the eggs of the Two Spotted Mite. Usually these products are recommended to be applied early in the season with full coverage over the tree/vine.

If the application of Predatory Mites precedes or follows too closely the application of these materials there is a very good chance you will starve the Predatory Mites. Predatory Mites primarily feed on Two Spotted eggs. If there are few eggs there is little to eat.

Strategy for use of Predatory Mites in this Situation:

Predatory Mites and preventative miticides can be used in conjunction but they need to be done so properly. First apply your miticides and wait for plant growth so there are areas where the product is not available to kill the Two Spotted Mites. Then apply your Predatory Mites. They then have a source of food when the Two Spotted Mites move onto the untreated areas of the plant.

The timing of this application is critical. You do not want to apply the Predatory Mites too soon (before there is any food). You also do not want to wait too long so the Two Spotted Mite population gets too large. The application of the Predatory Mites needs to precede the rise in Two Spotted Mite population

Watch your plants and undersides of the leaves. They will tell you when it is the proper time to apply the Predatory Mites.

Feel free to contact California Ag Supply with your questions.

Killing Miticides and Predatory Mites:

Killing miticides like Propargite, fenbutatin- oxide and others kill various instar to adult stages of the Two Spotted Mite. These products can be sprayed over Predatory Mites with minimal effect. The Predatory Mites we sell have a tolerance for these materials. If you are going to use these materials later in the season get your Predatory Mites applied as soon as you see Two Spotted Mites in the field. Let the Predatory Mite population build up with the Two Spotted population. Then when the time comes to use a Killing Miticide there will still be a residual of Predatory Mites to maintain control.

Feel free to contact California AG Supply with questions.

Watch for the next newsletter where we will discuss various pruning and suckering techniques that will help the use of Predatory Mites. We will also discuss using Predatory Mites for border, edges and hot spot control of the Two Spotted Mite.