What's New in Apple IPM - The Word on the Street

As every apple grower knows----life in the apple business is always changing, and the same can be said for integrated pest management in apples. Pest management in apples has come a long way over the past 35 years, and it continues to evolve as new chemistries and technologies become registered. Over the past year, I had the opportunity to attend several conferences on integrated pest management in apples to discuss ongoing research and issues relating to apple IPM. So what might the future hold for apple IPM?

Plum Curculio

Currently apple growers in the Northeast rely heavily on the use of broad spectrum organophosphorous (OP) pesticides to manage plum curculio (PC) and key pests of apples. Preliminary results from research conducted at Cornell University’s Hudson Valley Lab (R. Straub & J. Jentsch), suggest that Sevin XLR, a fruit thinner commonly used in apple orchards, may provide effective control of plum curculio when used at a specific time. Further research needs to be conducted to verify these results. If Sevin XLR is efficacious against PC, apple growers that use Sevin for fruit thinning may not need to provide subsequent applications of OP pesticides to manage plum curculio.

Dogwood Borer

Researchers at the Appalachian Fruit Research Station in the US have analyzed the pheromone of the female dogwood borer, and have developed a chemical lure that is significantly more attractive to dogwood borer males, than the pheromone that is currently used to monitor for this pest. This new improved pheromone should be commercially available in the near future, and will provide consultants and growers with a better method of monitoring dogwood borer populations in commercial apple orchards.

Obliquebanded Leafroller

Scientists studying pesticide resistance in obliquebanded leafroller (OBLR) populations in Washington have observed a slight shift in the insect’s tolerance to spinosad (Success). After 3 years of studies, the insects appear to be slightly more tolerant to spinosad, however this small change is not expected to result in field failures against even the most tolerant insects. Researchers believe that even if spinosad resistance continues to increase, spinosad will remain efficacious for at least 5 years, or perhaps even longer provided resistance management strategies are used. There have been no studies conducted in Ontario to evaluate OBLR resistance to spinosad, as a result Ontario apple growers should continue to rotate the chemical families (Success, Dipel/Foray, Confirm/Intrepid) to avoid the development of pesticide resistance.

Stink Bug

Stink bug damage has become a concern in many US apple orchards in recent years. In 2004, USDA initiated a research project to evaluate the susceptibility of various apple cultivars to stink bug damage. The results of this research suggest that “Jonagold”, “Empire” and “Braeburn” apples are highly susceptible to stink bug injury. In comparison “Honeycrisp”, “Gingergold”, “Golden Delicious”, and “Red Delicious” apples are moderately susceptible to stink bug injury, while “Gala” is considered to exhibit very low levels of damage from stink bugs. This information is very useful in orchard monitoring, since it will allow scouts to focus on varieties that are susceptible to attack by stink bugs.

Codling Moth

Over the past few years, researchers have been studying the potential for using a pear ester, one of the chemicals responsible for the pear’s odour, to attract codling moth (CM) adults and larvae. Unlike pheromones, which are only attractive to males, the pear ester is attractive to both females and males, and has the potential to be a useful tool in monitoring and managing codling moth populations. Researchers have already shown that the use of pear esters can increase trap catches of CM adults in walnut, apple and pear orchards. This technology may also be useful in controlling CM populations, since improved timing of sprays and the use of mating disruption and or bait stations could allow growers to eliminate female CM and prevent them from laying their eggs.