Mating Disruption in Ontario Apple Orchards

Research has shown that mating disruption (MD) is very effective in managing oriental fruit moth (OFM) populations in Ontario peaches; our direct experience regarding its efficacy in apples has until 2003 been rather limited. Population levels and damage to apple blocks observed in subsequent years has suggested that many production areas are faced with high pest pressure, a factor that can seriously jeopardize the success of MD. The use of MD requires low population levels of the target pest in order to be effective. As a result, it works best when used in conjunction with insecticides applied to help reduce initial pest populations.

This past season, trials were conducted in Ontario apple orchards to examine various pest management strategies’ effectiveness at reducing OFM populations to manageable levels. In subsequent years, once insect populations have dropped to acceptable levels, mating disruption (in conjunction with an early season insecticide spray) will be evaluated for its ability to provide season long control of OFM in Ontario apple orchards.

Experimental Design

Three commercial orchards with low to moderate levels of OFM pressure were selected for this trial in Southwestern Ontario. Insecticide sprays for the 1^st generation were applied 6-10 days after an upswing in OFM populations (based on pheromone trap counts) and 3-6 days after an upswing for subsequent generations. Isomate M Rosso pheromone twist tie dispensers were applied at a rate of 200 dispensers per acre on June 11^th and 13^th, 2003. Damage assessments were conducted following each generation to assess the efficacy of each of the treatments.

Table 1 - Programs for Managing OFM -Year One

Generation	Program 1 (conventional program only)	Program 2 (conventional+MD)	Program 3 (Mixed Program)
1st generation	Pyrethroid	Pyrethroid	Pyrethroid
2nd generation	Assail	Mating disruption +Assail	Mating disruption
3rd generation	Assail	Mating disruption+Assail	Mating disruption+assail
4th generation	(Decis)*	(Decis)*	(Decis)*

Results

It should be noted that 2003 proved to be an excellent year in which to implement MD, as population pressure was quite low throughout much of the province; this unfortunately makes it rather difficult to see noteworthy differences in program efficacy. Nevertheless, the results are encouraging for MD.

There was complete trap shutdown in the mating disruption blocks at all sites. Traps in the conventional blocks still continued to catch low to moderate levels of OFM. The level of OFM damage observed in all of the treatments were well below 1-2%, the level above which concerns arise that the pest management strategy used may not be providing adequate control. All of the treatments tested provided effective management of OFM in 2003, and the use of any of these programs should help growers to manage OFM populations in Ontario apple orchards. There were no additional benefits from using conventional products in conjunction with mating disruption. Levels of OFM damage were extremely low in all of the experimental plots this year, and as a result, it is difficult to determine if one of the management programs is more efficacious than the alternatives.

Acknowledgements

Materials for this trial were provided by CBC (America) Corp., Dupont Canada. Thanks to Hannah Fraser, Neil Carter, Mike Morlock (Cargill AgHorizons), Kristen McGuire (Cargill AgHorizons), Colin Yates, and Fotios Zannas