Posted: Thursday, March 22, 2012 8:38 AM
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RALEIGH, N.C. (February 12, 2012) – Ongoing drought conditions have growers and consultants concerned about potential mite explosions when almonds and grapes come out of dormancy.
“We are having one of the driest winters in history,” says Mike Strmiska, owner of Strmiska Consulting in Fresno, Calif. “We had no rain in December and as of Mid-January that trend continues to drive a growing concern for how this dry spell will impact mite conditions once the season takes off,” he says. “The Two-Spotted Spider Mite and the Pacific Mite are the principal species that we are going to keep close watch over. When these species overwinter in drought years they come up out of the ground in enormous numbers and climb up trees at the first sign of leaf development. Their sole mission is to lay eggs and start the process of mass reproduction.”
Doing the math
Few pests can flare up and explode as quickly as mites. Soaring temperatures are when female mites become most prosperous in their feeding and laying of eggs.
One adult female mite can produce up to 120 offspring during a single reproductive cycle. When optimal temperatures range between 93 and 95 degrees Fahrenheit, life cycle development from egg to adult can occur within seven days.
In as little as 21 days, 60 female mites have the potential to produce 26 million adults by way of re-population in just four generations. Left untreated over this same 21 day timeline, mite populations can surge from one generation to the next, resulting in a non-stop feeding frenzy that often causes devastating crop losses.
“One or two adult mites per leaf won’t rob the crop of yield,” says Patrick Dosier, Western Regional Market Development Manager for MANA Crop Protection in Palo Alto, Calif. “But left untreated with minimal monitoring during an upward fluctuation of temperatures - what might be viewed as a small concern can quickly turn to into big problems with populations hitting the billions in just a few days.”
Every high-value crop grower understands the importance of effective mite control. The question is whether to get a jump on mite control early with an ovicide treatment or to take a wait-and-see approach by relying on adulticide inputs once populations hit a threatening threshold level.
“Some growers don’t like to spray until they see mites at a certain threshold,” says Dosier. “In almond fields, growers typically expect mites to show up sometime during the season. Mite populations on grapes are not as predictable from year to year. However, for either crop, if and when conditions are ideal for mite activity, a preventative approach to the problem is the best course of action against yield and quality losses.”
Strmiska concurs. “In years when mites have come charging into high-value crop areas, the problem becomes immediate with little time to react,” he says. “Using an early-season ovicide spray makes sense as a treatable solution from at the earliest point of contact for control. Ovicides don’t kill existing adult mites currently feeding on foliage, but are used to reduce the size of the next generation by impacting the reproduction cycle of the female.”
Extension entomologists advise that the best strategy for season-long containment of mites include scouting, threshold monitoring, adoption of high performing inputs that manage populations, preserve beneficial insect populations, and also judicious use of adulticides.
Dosier says these recommendations are best served when they complement each other under an integrated pest management approach. “You want the efficacy of an IPM strategy to be greater than the sum of its individual components,” he says. “Growers obtain the greatest value from their crop protection investment when the components act synergistically. An early ovicide application is a tool that manages mite populations before they explode; it enables the grower to break out of the reactive adulticide strategy and offers more flexibility and options in the later season. This proactive approach prevents mites from robbing one iota of yield by providing a long residual that prevents populations from even approaching ‘economic’ thresholds.”
Strmiska agrees. He strongly advises growers to get an early start by using an ovicide application soon as possible. By hitting the issue early with an ovicide, he believes season-long control occurs much easier and at less expense. From his experiences, he says an early ovicide application can often hold down costs by eliminating a later season adulticide spray since populations are greatly reduced from the onset.
On almonds, Strmiska recommends an Apollo® SC ovicide/miticide treatment just after petal fall, which is usually around mid-March to early-April. Apollo has a unique mode of action that targets ovicidal and early-immature stages of mite development. Adult females exposed to sprays or foliar deposits of Apollo lay non-viable eggs which interrupt the mite life cycle. This tool also offers up to 60 days or longer residual control following a single application.
The consultant advises growers to use an adequate amount of water for thorough coverage and to pay attention to travel speed which should be two- to two-and one-half miles per hour if the sprayer is engine-driven and two miles per hour if using a power take-off.
“For the past several years, I’ve witnessed good results when ovicides are administered early-on as a foundation tool for a mite program,” he says. “They are dependable solutions that work against the potential for later season population increases.”
The consultant draws out that Apollo also has an advantage in being soft on beneficial insects, predatory mites and pollinators.
As we all know - adulticide products can be harsh on natural enemies. According to Dosier, certain adulticide tools can work against their intended objective. “This occurs when more sprays are required than originally planned to offset flares of secondary pests,” he says. “When predatory mites are wiped out from an adulticide treatment, the pest population can often rebound more rapidly which can result in greater economic damage than the original mite issue.”
Results alongside costs
Growers who have never used an ovicide are the first to ask about costs associated with early season sprays versus the ‘wait-and-see’ method.
Dosier advises growers to look at all of the factors when evaluating this kind of decision. “Certain adulticides can be inexpensive to use only as long as they remain effective,” he says. “An ovicidal tool like Apollo offers a completely different mode of action and a proactive strategy in addressing mite management. It allows growers to take initiative with a preventative method which lays down pre-emptive security against yield loss. This product is also highly effective for resistance management challenges based on its unique and differing mode of action.
“Plus, with adulticides, growers often lose the added defense that comes from good insects feeding on the pest. More times than not, a lack of beneficial insects will result in more sprays. Apollo has no negative impact on beneficials.”
Both Dosier and Strmiska believe the economics for using an early-season ovicide are especially favorable for this coming season, especially with forecasts calling for a dry, hot spring.
“This year more than ever, an early start on mite control appears to be the best way to maximize the return on investment for season-long management,” says Dosier. “An early application of an ovicide will help keep mite populations in check for the lengthy spring and early summer mite seasons. With all signs pointing toward dry weather and heavy mite pressure, a strong start for gaining immediate control this spring will be critical for a strong finish next fall.”
For more information about Apollo ovicide/miticide visit the MANA Crop Protection mite management website at www.miteexperts.com or call 866-406-6262.