How About Those Apples?
A multi-year SARE project takes a holistic approach
Maurice Tougas learned in late May that plum curculio, a summer apple pest, had invaded his Northboro, Massachusetts orchard. He considered it excellent news. The plum curculio is a beetle that feeds on young apples and deposits eggs in maturing ones; for years, apple researchers and growers have sought a trap that will tell when the pest makes its appearance.
"We knew we had to spray after petal fall, but the traps also tell us when we can stop spraying," says Tougas. Finely tuned traps, developed in the course of two SARE grants, allow Tougas to base his decisions "on solid information rather than guesswork."
Tougas is one of a group of New England apple growers collaborating with a team of University of Massachusetts researchers to develop more sustainable orchard management practices. In addition to plum curculio, this effort also targets European red mites, apple maggot and flyspeck disease—pests that, along with apple scab, account for more than 90 percent of pesticide use on apples in the Northeast. The goal is to develop an approach that integrates pest control and horticultural practices.
"This project is important to apple growers," says Tougas, "especially with the future of pest control materials so uncertain."
This uncertainty is the result of a combination of factors. Some pests are becoming resistant to common pesticides, and some growers are facing increased pesticide costs. There is also the potential loss of some pesticides to regulation, and increasing restrictions on re-entry periods after spraying. Newer, more selective pest control materials have not been as effective against key apple pests as some broad-spectrum sprays were.
As a result, Tougas, like many growers in the region, is looking for alternatives. Approaches that substitute biological controls for chemicals are the next logical step. Ron Prokopy, an entomologist at the University of Massachusetts, says, "It makes sense to move toward a method that intervenes less in the orchard ecosystem. It’s a more environmentally sound approach. You have less impact on other organisms, including humans, and you end up with fruit that has very minimal residues."
The project includes evaluating the influence of cultivar selection, arrangement, tree size, and planting density, along with using horticultural practices as the first line of defense. By developing and fine-tuning traps to monitor when insect pests are a threat, the researchers eventually hope to use traps not just to monitor, but to capture them. The project is also studying diseases such as flyspeck and sooty blotch to understand more about how they are spread, and the participants are developing a model that includes weather and orchard conditions to help predict the risk of infection.
So far, the research indicates that a combination of horticultural practices, biological controls, and spot pesticide sprays can be effective. For example, careful pruning and reduction of wooded orchard borders can reduce the risk of flyspeck infection, says Daniel Cooley, a University of Massachusetts plant pathologist. Spot sprays to control flyspeck, which tends to be greatest near orchard perimeters, can provide control at a fraction of the cost of typical spray regimes. Reducing fungicides can prevent some mite problems because fungicides harm naturally occurring mite biocontrols.
The next phase will look at the effect of tree arrangement and the habitat just outside the orchard on biological controls—some cultivars are more resistant to certain pests, and where they are placed in the orchard may affect the spread of pests. Similarly, having an open field, wooded areas or hedgerows adjacent to an orchard may influence pest pressure. It’s a subject that hasn’t been given much attention, and this multi-year project offers a remedy.
For more about this project, call 802-656-0471 and request materials on LNE97-90 and LNE00-135.
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