Timing is everything in pest management. Say you’re sampling for leafrollers. If you go out looking for them in your orchard at a time when they’re very tiny and almost impossible to see, you might conclude you don’t have any and move on to another block or job. Two weeks later, you might be facing leafroller damage and think the leafrollers moved into the orchard from outside, when it was really just a case of looking for them at the wrong time.
Washington State University entomologist Dr. Vince Jones has developed a Web-based system that growers can log onto that will tell them what’s going on in their orchards, what will be happening in the near future, and give recommendations on how to deal with it.
His Decision-Aid System started out as a way for Jones to keep track of his own research projects and make scheduling easier. “For research, I can’t afford to do things at the wrong time,” he said. “You have to be there at the right time, and we have so many projects that it’s hard to keep track of them.”
With the traditional, broad-spectrum pesticides, timing was less critical. “You had a lot more slop with the old products—they had longer residues and targeted a wider range of insects,” he said. “With the newer materials, the residue generally isn’t quite as long and not quite as active, depending on what pest you’re talking about. Timing becomes more and more critical.”
Degree-day models for major pests and diseases are part of the on-line Decision-Aid System, along with clear indications about what they mean in terms of sampling and spraying. The models are powered by near real-time weather data from Washington’s AgWeatherNet, which gathers input from 120 weather stations around the state. Users can select the closest weather stations to their orchards and receive recommendations for their locations, or they can cut and paste in weather data from their own stations.
Based on the weather data, the program might indicate the percentage of codling moth emergence and the percentage of egg hatch and recommend sampling or control strategies. It might also warn, for example, that if 3 percent of the eggs have hatched, then every 20 degree-days that you delay control, you can expect 3 to 5 percent more fruit damage.
It can also provide recommendations for the coming one to ten days, based on projections from the U.S. Weather Service, which issues forecasts based on a three-by-three-kilometer grid. Corrections are made to the forecast, depending on where the user’s site is in relation to its weather stations. Users need to enter their GPS coordinates, which can be obtained from GPS units or by pinpointing their location on Google Earth.
WSU still puts out the spray guide (Crop Protection Guide for Tree Fruits in Washington) in paper and on-line formats, but the Decision-Aid System integrates all the things that are happening in the orchard at the same time.
The system includes a pesticide database to help users choose from available materials. Rather than just seeking recommendations for codling moth, a user can query the program for the best option and timing to control both codling moth and leafrollers with a single spray or target other combinations of pests. Or, with the click of a mouse, a user can eliminate all organophosphate pesticides from the recommendations. Jones plans to include more information about natural enemies and show the times during the season when they would be least likely to be affected by the various pesticide applications.
“I think we’re going to get a lot better at understanding the impacts of our insecticides, not only on the pests, but on the nontarget pests and natural enemies,” he said. “We’re looking to allow people to understand the full impact of what they’re doing. If we can understand how different things interact, we can start to give at least some predictions on how to deal with that.”
Parts of the system that were beta tested last year by researchers and industry representatives are available to the public. Degree models in the system include codling moth, obliquebanded leafroller, pandemis leafroller, San Jose scale, campylomma, lacanobia fruit worm, apple maggot, cherry fruit fly, fireblight, and storage scald.
“I think this will be a great thing,” Jones said. “The ability to schedule things better is going to help everybody. You don’t want to be sampling when nothing’s there or applying pesticides when it’s too late or too early, and the previous models were not interpreted well.”
Traditionally, the codling moth model has been set at Biofix, which Jones said has been a source of confusion. Biofix is the first consistent trap catch, but growers are sometimes unsure of when that is. Jones would like to switch to a model based on accumulated temperatures from January 1, to eliminate uncertainty.
The Decision-Aid System, which has been funded by the Washington Tree Fruit Research Commission, will continue to evolve over the next three years. By next season, it should include models for peach twig borer, white apple leafhopper, and more diseases, such as mildew, apple scab, and Coryneum blight, as well as an updated fireblight model.
Jones stressed that the program doesn’t make decisions for orchardists. The aim is to give people—in a way that’s simple to understand and digest—information on what’s going on and what’s likely to happen, he said. “But we’re not making the decision for them. It enables them to make an informed decision and enables them to plan better.”
Output from the program can be e-mailed to the user at specified intervals. Jones expects that it won’t be long before the system is able to automatically send growers or consultants a text message on their cell phones to warn them of a high risk of fireblight.
Lee Gale, past president of the North Central Washington Fieldman’s Association, said that the Decision-Aid System should allow for a more surgical approach to pest control, rather than a shotgun approach. It could also help demonstrate to the public how responsible growers are in terms of chemical applications. “We can promote this, and it can do a lot of good,” he added.