The weather extremes that seem to be hitting us more and more in the past few years have driven waves of increased pest infestations across the country. Gypsy moth caterpillars have defoliated hundreds of thousands of acres in the Northeast. Tiny mites are spreading rose rosette disease across the Midwest. Polyphagous shot-hole borers are eating their way through Southern California. Emerald ash borers (EAB) are killing ash trees . . . well, practically everywhere, it seems.
With all these creepy crawlies working their way across your clients’ landscapes, you might feel like dipping your tools in pesticide, or putting on a HAZMAT suit and walking around in a permanent cloud of insecticide. However, there is a better way, one that balances the needs of the landscape with the realities of the environment. Namely, integrated pest management, or IPM.
Molly Keck is an IPM program specialist with Texas A&M AgriLife Extension in San Antonio, Texas. She compares it to the food pyramid. “At the bottom of the pyramid, where you put the most emphasis, are the cultural controls,” she said. For the most part, cultural control means keeping plants healthy so the landscape is more resistant to insects and diseases, something we do already.
Regular mowing is a part of this equation, as it helps grass to grow, as is scheduling irrigation for deep watering, broken up by dry spells, to encourage root systems to grow deeper. Avoiding synthetic fertilizers and encouraging mycorrhizal growth is also good for long-term plant health.
The next step up includes mechanical controls like putting up physical barriers or, in the case of invasive plants, pulling weeds. Landscape fabric is another example of a mechanical control. You lay it in a land scape bed, under the mulch, and it acts as a weed barrier.
If cultural and mechanical controls are insufficient, then the next recommendation is to use biological controls. “That’s using good bugs to kill the bad bugs,” explained Keck. “You can do that by introducing the right bug, to kill the insect that’s giving you problems, and also won’t upset the natural ecology.” Sometimes, the right insects are already there in the landscape, but their populations are being suppressed by pesticides.
When all else fails, IPM does allow for the use of chemical controls such as insecticides, fungicides and herbicides. “IPM isn’t about eliminating chemicals, it’s about reducing the need for them by using other tactics,” Keck said. “A lot of times, if you are using other methods, you don’t have to use synthetic or organic pesticides.”
Knowing the pyramid and the value of judicious pesticide use is important, but you have to know what you’re up against first. If you don’t know what plants you have in a landscape, you won’t be able to find out which bugs might be a risk for them. If you don’t know which bugs are the biggest problems in your region, you’ll be blindsided when they show up in your clients’ landscapes.
“The first part of an IPM program is being able to identify what plants you have, and the second part is being able to identify the insects or diseases that can attack those plants,” says Walter Swift, owner of Swift’s Creative Landscapes, Inc., in Hopedale, Massachusetts. “The third thing is having a good understanding of what we call ‘growing degree days’.”
Growing degree days (GDD) is an important horticultural measurement of heat accumulation, and GDD numbers are used to predict when pests will emerge. Many of the more environmentally-friendly pesticide options, like horticultural oils, require precise timing to kill the targeted bugs without killing a lot of good insects along the way.
Learning about GDD numbers can help you time your applications well, and adapt—when, for example, an unexpected run of warm weather causes a local pest to start hatching early. Most agricultural extension services monitor and post local GDD information online; they are also likely to have information on the local pests and how to fight them.
Once you know your plants and your pests, you can design a battle plan. Swift tries to draw up his so that they will have as little impact on the local wildlife as possible. “I don’t want to go spraying a tree for caterpillars, and then find that the tree has a robin’s nest in it, with a bunch of eggs, and I’ve just sprayed insecticide on them,” he said. “So, before we spray, we inspect the entire tree.”
Sometimes, with inspection and mechanical controls, you can avoid spraying altogether. For example, Massachusetts currently has a major issue with gypsy moth caterpillars. They ate and defoliated more than 350,000 acres across the state last year, and are expected to be worse this year. They hatch from tan-colored, cottony egg masses of 500 to 1,000 eggs each. If you can spot the egg masses on the trunks and branches of trees, you can remove them by hand.
In cases where egg removal isn’t feasible, horticultural oil is also a good choice. “Dormant oil spray is one of the best treatments to use for killing egg nests, prior to the caterpillars’ hatching,” said Swift. The oil clogs up the spiracles (respiratory openings) of insects, suffocating them. The oil evaporates quickly, and is only effective if sprayed directly on the pest, so careful application is key. However, it is organic and won’t hurt most plants.
Organic pest-control options have been gaining ground in Swift’s market, and he’s been looking into them, to stay on top of the trend. Another major property-owner concern he’s become aware of has to do with the dwindling number of honeybees. What’s become known as the honeybee ‘colony collapse disorder’ is affecting bees nationwide, and although the cause has not been nailed down, insecticides are seen as contributing to the problem. “We have to use discretion when using pesticides, especially powder insecticides,” he said. “Bees naturally pick up pollen grains, and the powder is very similar to pollen grains. So the bees will bring it back to the hive, and it will affect the entire colony.”
Taking that kind of wide view is vital to the success of a good, longterm IPM program. You want to know the history of the property, what lengths the owner would be willing to go to in order to save a particular tree, or to ensure that a communal area looks perfect. IPM is as much a matter of responsible crisis management as it is technical know-how.
In St. Charles, Illinois, Jim Turcan, president of Cornerstone Partners Horticultural Services Company, has found that when he picks up a new client, the first season is spent reacting to the existing problems. “If it’s a brand-new job site, we’ll propose fixes to our clients for their properties,” he said. “We take any problems that are evident on care of the things that must be addressed immediately, then take a reactive approach to that first growing season.”
In subsequent years, once his crews are no longer putting out fires, then they can start doing more with less by planning things out. Using the plant information from the original survey, and knowledge of the local threats, they can make educated guesses as to what problems might arise, and what plants might be infected. From there, Turcan’s crews can emphasize the health of the most at-risk plants, and make targeted applications where needed.
The estimates are backed up by an ‘arbor scouting’ program, where one of the company’s certified arborists walks through the entire property and visits every plant. This detailed, monthly inspection has an allowance fund from the property owner attached to it, so any issues that are found can be treated on the spot, without a time-consuming approval process.
“It’s been a very welcomed program by our clients,” said Turcan.
“Because some of these harmful pests can develop rapidly, within 48 hours. If we notice something, we can’t wait a week or two weeks for approval. We’ve got to hit it right then and there.”
He backs up his actions with rigorous documentation, noting every plant, every disease, every treatment. It reassures clients that they aren’t paying for unnecessary sprayings or injections, and gives them a jumping-off point to ask questions, and educate themselves, if they’re interested in doing so.
As you might imagine, learning about IPM is as deep and complex as learning about ecology in general, and there’s always more to discover. You read about plant diseases, and discover the importance of removing infected yard waste. You read about good fertilization habits as it pertains to cultural controls, and discover the damage that turf can cause to a tree when it’s growing too close to the trunk.
Most of us work in this industry because we enjoy nature; we both care about it and care for it. If you find that learning the ins and outs of IPM gets you excited and builds a sense of enthusiasm, then share it with your employees. Take five or ten minutes out of your day to talk about what new things you’ve learned. You may find that getting engaged with plant health is infectious.