Managing Oriental Fruit Moth as a Cross-Commodity Pest

Fruit infestation by Oriental fruit moth (OFM) can result in devastating losses to producers of tender fruit and pomes. Management strategies are well-established for tender fruit, and are being developed for apples and pears. Several product chemistries including organo-phosphates, pyrethroids, and neonicotinoids are registered for use in Canada; when these are coupled with mating disruption (MD) technology, growers can develop effective and sustainable pest management programs.

Over the last two years, we have discussed the virtues and limitations of mating disruption technology in several OMAFRA publications (Hort Matters, Tender Fruit Grape Vine, Orchard Network Newsletter, factsheets, infosheets, webpages), not to mention at countless industry meetings and conferences. We will not go over these in detail here, but keep in mind that MD works best in large blocks, ideally when applied in expanded acreages or as part of a coordinated area-wide program. Mating disruption programs must include regular scouting, preferably overseen by an experienced consultant. The technology requires an initially low pest population; often this is achieved through the use of insecticides directed at first generation larvae, season-long management with insecticides in the previous year, or through a transition year using both MD and insecticides.

When you are considering using MD in your orchard, keep in mind that OFM are quite capable of flight. Even if you are managing OFM on your farm, females mated "off-site" can fly into your orchard and lay their eggs on your crop. Knowledge about your neighbour’s management practices can provide information on the "weak points" of your own. Reviewing a scenario or two may help in this regard.

Let’s assume that you are not part of an area-wide program, but are using MD to manage OFM in your apples (minimum 10 ac, continuous, "square" block). You also produce peaches, and have chosen not to apply MD in those blocks (or perhaps you managed the first generation with an insecticide and treated the remaining generations with Isomate M100, which lasts 75-80 days and will get your peaches safely to harvest, by early September). You applied an insecticide to manage the first generation in apples this year, and the Isomate Rosso product (120 days efficacy) you applied before the second generation emerged will get you through to harvest. So what is the weak point in this strategy? OFM can fly well into October, potentially causing late-season damage at or near harvest. You may not be worried about your peaches, because they are harvested by September. But if the last generation is not being managed in peach blocks, any emerging adults can mate and potentially move into your apple blocks.

A similar problem arises when your neighbours don’t manage all 3-4 generations of OFM.

One grower using MD for the first time this year reported that he had great success in his apples and peaches, but had some damage to his pears. As it turns out, he had managed the first generation with an insecticide, then had applied Isomate M100 to his entire farm for subsequent generations. He successfully harvested his peaches by the end of August, and then decided to treat the last generation of OFM in his apples with an insecticide, because he knew the Isomate M100 efficacy period had expired. But he took a chance with his pears, which were close to harvest, and left them unprotected – hence the damage to the crop in September.

Even if you use MD on your whole farm, you need to be aware that "unmanaged" females can migrate into your orchard through the season. This type of damage is most often associated with border areas, and provides a great case for coordination with neighbours and the adoption of "area-wide" programs. One solution, though not validated in Ontario, is to spray border areas with an insecticide (timed to coincide with regional activity and egg hatch), or to extend MD 20-40 m outside of the orchard your are trying to protect. In any event, do not leave your crop unprotected.

Exploring area-wide or extended acreage MD programs are well worth your while. Keep in mind, however, that not all areas are well suited to the technology. In some cases, growers may have to rely on evolving strategies that incorporate insecticides into IPM programs.

Editor's Note:

In this issue we present the results of applied research efforts to manage OFM in Ontario apple orchards. For more information, contact the authors as indicated in the articles.

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