The Value of Christmas Trees

"...there is no reason why the joy associated with the Christmas evergreen may not be a means of arousing in the minds of children an appreciation of the beauty and usefulness of trees; and keen appreciation of the beauty and usefulness of trees is a long stop toward the will to plant and care for them (Arthur Sowder, US Forest Service, 1949)."

Monday, July 18, 2011

Movento and Rosette Bud Mites

Field where Movento applied in Avery County.

On Friday, Jerry Moody and Doug Hundley with Avery County Extension helped me evaluate rosette bud mite control in a grower’s field. I reported on this study on June 15. Then I just pulled some shoots at random to see if I could find any rosette bud mites. But now you can clearly see which buds look like rosette buds and if there are living mites present inside the bud.

Currently our best control has been to apply Dimethoate when the new growth is out 4-6 inches. A few growers have also tried Mavrik during that time frame with some results. But these have always been with a high pressure application.

Some growers have gotten good control with Dimethoate using a mistblower if they use a lot of water per acre (50+ gallons) and/or treat twice during that June treatment window. We were interested in trying the new systemic material, Movento with a mistblower.

Don’t confuse Movento and Safari. They are two different chemicals from two different chemical families. The active ingredient in Movento is spirotetramat. It is labeled at 5 to 10 ounces per acre.

The following two statements are from the label:

“Movento is a suspension concentration formulation and is active primarily by ingestion against immature target pest life stages. In addition, fertility of adult female target pests, such as aphids and whiteflies, may be reduced.”  This means that the pest has to feed on the plant having Movento in it to work. It also means that it will take some time for the product to work, as it is affecting pest development and fertility.

“Movento must be tank-mixed with a spray adjuvant/additive having spreading and penetrating properties to maximize leaf uptake and systemicity of the active ingredient within treat plant.” We have successfully used the adjuvant Liberate (which also makes droplet size larger, making it a good choice for mistblowers) and a 1% horticultural oil solution.

When Jerry and I tried this product last year for twig aphid control, we saw one tree that had rosette buds that didn’t have any following treatment. Since we were treating in mid April, it appeared that the systemic action of the Movento was getting into the tree and preventing the rosette bud mites from developing.  It had time to work throughout May and into June to control the mites.

This spring, we got Clay Cutherbertson in Avery County to apply the product with his mistblower. He treated in April using 10 ounces per acre and about 70 gallons of water per acre. Friday we went through those blocks, and found very few trees that looked like they had rosette buds on 2011 growth, and those few buds had no live mites in them. (Actually I did see one live mite under the microscope, but it was in a fully formed, normal bud and could no longer create a deformed rosette bud).

This is just one study in one field, but it looks very promising. A spring application of Movento with a mistblower may well control two of our most difficult to control pests – balsam woolly adelgid and rosette bud mites. Twig aphid control with Movento is only fair, but in fields that had twig aphid control from the fall, or by adding another material such as Talstar which works well against twig aphid (that’s why Clay did), you can control multiple pests in the spring.

Like most studies, this little test creates some more questions. Does Movento have activity against rust mites which are quite similar to rosette bud mites? Can you treat with Movento any time of year and control the mites inside the bud? These are some things we’ll be looking at in the future. Keep checking back to the blog for more information about Movento and other chemical controls.

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