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.

Some Results on Pest Control

We're seeing more twig aphid damage than I anticipated. After all, it wasn't easy to find twig aphids in April. Plus we had lots of rain and cooler temperatures which tend to reduce the survival of the aphids. But they are well adapted to western NC, and they have ended up causing some damage.

BUT... with all the rain, a lot of the damage is disappearing. I spoke with Bryan Davis who told me that he is seeing less needle curl in fields this week even than last week. Thanks to the rain, the majority of this curl will go away.

This leads me to some data to report from my current studies.

FALL TWIG APHID CONTROL: Last fall, Jerry Moody and I treated some trees October 18, 2010. Really we were trying to see how late you could treat in the fall and still control elongate hemlock scale. But I also wanted to see if the treatments would control twig aphids the following spring. We tried Safari (applied to the foliage with a high pressure sprayer at 8 oz/100 gallons), Lorsban, and the standard Dimethoate + Asana.

I did evaluate scale control this spring, and none of the products worked well. This wasn't surprising as mid October is probably too late to get much scale control. However, I also evaluated BTA control this spring with these fall treatments and those results are pictured here.

Remember that I evaluate twig aphid damage by either walking around the entire tree (which makes me dizzy!) or working with a partner. For these observations, I worked with Jerry Moody. We walked on either side of the tree and estimated the percentage of 2011 new shoots with needle curl each on our respective side -- then we come to an average figure for that tree. These result in the numbers in the first column (% shoots with curl) -- averaged for all 20 trees. The next column has the percentage of the 20 trees with at least SOME needle curl. The third column has the percentage of 20 trees with 10 % or more of the needles curled. This is the point where most growers tell me the damage is bad enough to affect the value of the tree. Of course remember that the needle curl will decline over the next several weeks, so all of these numbers will go down. Still, the comparison now when the damage is at its greatest tells us how well the products are working.

Obviously, neither the Lorsban nor the Safari are giving us any twig aphid control when applied in the fall. The Asana + Dimethoate worked well, though not perfectly. In fact, Brad Edward's observation this spring has been that the Asana in the fall isn't working quite as well as the Talstar applied in the fall. It works, but a bit of curl gets through. These results bear this observation out, and in fact the first year I did this type of work at Omni Farms, that was our observation. Still, the Asana + Dimethoate gives good enough control and it would be more effective against scales.

SPRING CONTROL WITH SYSTEMICS: So how well does Safari and Movento work in the spring? Jerry and I applied these products at two farms, treating on April 18, 2011. In this instance we applied the Safari to the base of the tree trunk and not the foliage, using a rate of 1 pound per acre. At two farms we did this with a high pressure sprayer, and at one farm just with a backpack sprayer. The Movento and bifenthrin are applied with a high pressure sprayer to the foliage.

The results again demonstrate that Safari isn't giving us twig aphid control. Practically all the trees had some needle curl when treated with Safari. The Movento gives fair control. A lot of trees have some curl, but hardly enough to worry about. The bifenthrin is of course the best.

At these two farms there was also scale and woolly adelgid. We will be looking at the control of these pests later on in the summer, so stay tuned!

OTHER OBSERVATIONS THIS SPRING: Once again, several people I've spoken with this week are commenting on spider mite activity. The rain is reducing mites to some extent -- probably by increasing predator mite activity, but it is still important to scout for spider mites and make sure they don't damage new growth. The good news? All of this hot weather should be taking care of any rust mite issues!

Movento Gets Relabeled

According to an October 18, 2010 press release from Bayer CropScience, Movento insecticide has received EPA registration for a second time. The original registration of Movento was cancelled because of administrative errors committed by EPA during its initial review and approval of the active ingredient, spirotetramat, in 2008.

I have been working with this systemic material for the control of many pests of Fraser fir including balsam twig aphid, balsam woolly adelgid, elongate hemlock scale, and mites. I have been interested in Movento because it is systemic, has the potential to control a wide variety of pests, and is less toxic than many pesticides used on Christmas trees.

When I work with new products, I like to conduct my own spray trials where I can closely determine initial pest levels and really see how well the product is working. But I also like to get the product into the hands of growers to see how well it works in real farm situations. With the issues with the labeling of Movento, I haven't been able to work as much with the product as I would have liked. This ruling by EPA clears the way for more complete evaluations.