Typically, about 75 percent of the cost of treating for California red scale in citrus is directly related to the amount of water in the mixing tank to achieve adequate coverage.
Reducing water would reduce application cost.
“At 1,500 gallons of water per acre, which is normal for a California red scale application, it costs a grower $90 an acre just for the application, not including the chemical,” says Beth Grafton-Cardwell, University of California Cooperative Extension (UCCE) entomologist at Kearney Ag Center and Lindcove Research and Extension Center. “If we could somehow reduce the gallonage required for that type of application, it could result in substantial savings to the grower.”
Grafton-Cardwell and other researchers are currently testing at least one new product that just might deliver that bonus for growers. Movento, a tetramic acid, from Bayer CropScience is currently in the developmental pipeline on track for registration in several key tree and vine crops, according to Rob Schwehr, Bayer CropScience Insecticide Product Manager.
Movento is fully systemic foliar application with prolonged residual in plants. It has minimal contact activity and works primarily through ingestion. The product is effective against several pests including California red scale, aphids, whitefly, mealybug, Psylla, Phylloxera and thrips. It has also shown suppression on mites.
Grafton-Cardwell has evaluated the product in research trials looking not only at various rates of active ingredient, but also carrier volumes ranging from 250 to 1,000 gallons per acre. In one trial, she compared Movento to industry standards such as Lorsban and Admire. Red scale infestation was measured in both twigs and fruit. Very little cosmetic damage from California red scale is tolerated on harvested fruit for marketing purposes, while direct damage to the plant can cause dieback of branches and retard future tree and fruit development.
“Movento has good activity on red scale infesting both twigs and fruit,” she says. “It is a slow-acting material, taking about 10 to 14 days for results, which is not a bad attribute. It is non-toxic to vedalia beetle and Aphytis which are important natural enemies to red scale.”
In laboratory tests, Movento proved 99 percent to 100 percent effective against first, second and third instar stages of red scale evaluated 14 days after treatment. “Some of the first instars made it to the second instar stage,” she says. “Some of the second instars made it to the third instar stage and so on, but they eventually died. It's a slow-acting material, but it is ultimately very effective on red scale.”
“If we could lower the gallonage like it appears we can with this product due to its systemic activity, that would make it very attractive to citrus growers,” Grafton-Cardwell says.
Interestingly, it's the slow activity against red scale that also appears to work to the product's advantage when it comes to preserving natural enemies. “I think the fact that Movento is slow-acting helps preserve Aphytis melinus,” she says. “Aphytis is protected initially because it's under the scale which it's feeding on. Then Aphytis can continue to feed on the scale because the scale is not immediately killed and thereby disrupting its food source. It can continue to develop. You don't see that phenomenon with other insecticides.”
At present, EPA registration of Movento is expected in the third or fourth quarter of 2008, or perhaps even earlier, according to Schwehr. If that timeline progresses as anticipated, full U.S. launch, including California, could occur in early 2009.