After several glorious weeks of garden weather, Larchmont’s gardens are in full bloom with hydrangeas, lilies, phlox, and roses. Containers are overflowing, and the vegetable harvest has moved from lettuce to tomatoes.
But, wait! Lurking in that bounteous display may be rabbits, slugs, skunks, grubs, powdery mildew or tomato blights. It’s time to consider Integrated Pest Management (aka IPM).
Why is IPM important?
IPM is a practical, sensible approach for maintaining your garden in an ecologically responsible way. It relies on good garden practices that you already use. IPM contributes to a healthy environment by reducing the use of pesticides. It can also save you money.
IPM has five basic components:
* Prevention: To avoid pests, experts recommend some basic strategies. By now, you know most of them. Choose the right plant for the right place (what, again?) because plants thrive in locations that are best for them and are less susceptible to fungal or bacterial disease. Select disease-resistant varieties; labels or catalogues often provide this information. Plant with enough space to promote air circulation: wet leaves foster disease spread. (We know; record-breaking rain in June makes this tough.) Fertilize and prune your plants, shrubs and trees when it’s appropriate: healthy gardens are happy gardens. Keep your garden beds clean: fallen leaves and branches can harbor diseases, feed insects, or provide shelter for animals. Don’t work in a wet garden because water can spread disease.
* Monitor: You already make little trips around your garden each day to deadhead or weed, right? Well, now it’s your chance to play detective. Check your garden for signs of damage. Flower stems stripped of leaves or blooms? Holes on the edges or centers of leaves? Brown areas in the lawn? Whitish spots on lilacs? Dark concentric circles on tomato leaves? Yup, your garden has issues.
* Assess and analyze: Here’s the tricky part. Deciding if these are problems depends on whether you can tolerate them, the kind and quantity of pest that are creating them. I’m not obsessed about white spots on my lilacs (see powdery mildew below), but it may really bother you. On the other hand, I can’t stand holes in the hosta leaves (see slugs below). If you don’t know what the pest is, you can look it up on the Cornell website or take a sample to Cornell Cooperative Extension for an analysis. There are some pests, however–Dutch elm disease, emerald ash borer, Asian long-horned beetle – that you must address immediately because they not only threaten your garden but others as well.
* Act: Here’s where your choices come into play. Total eradication is often not the required option. You can use cultural practices like removing diseased leaves from columbine or picking Japanese beetles off roses; biological practices like encouraging beneficial insects such as lady bugs and lacewings; or chemical practices like herbicides, fungicides or insecticides. If you decide to use chemicals, be sure to follow the directions about “dosage” just like you would with your own medications. Also, be practical: it doesn’t make sense to spray on a windy day or before rain.
What Do I Do About…
So, let’s talk about the pests that everyone in Larchmont seems to have.
Rabbits. This seems to be a bumper year for these critters. I watched a mommy rabbit give birth to three adorable bunnies in my garden this spring. Are they pests? You bet. First they ate the tulip blooms; now they’re enjoying the obedient plants. They don’t even clean up: they just leave the remains of the poor stems next to the denuded plants. Rabbits aren’t diggers and they don’t like to climb, so one of the best ways to prevent damage from them is to use 2-foot high chicken wire fencing that is tight to the ground. You can also place a dome or a cage over the bed. Another option is to use a taste repellant like blood meal, but it only protects the parts of the plant that is touches and doesn’t last long. Some people have had success with hot sauces but anecdotal remedies are not sanctioned by University research.
Slugs. Those holes in your hosta leaves? It’s likely that slugs are responsible. The evidence? The patches of dried slime they leave behind. How do you get rid of these guys? Slugs are night feeders. You can go out in the dark with your flashlight and remove them by hand-putting them in a bowl of soapy water. If that doesn’t sound appealing-and it doesn’t to me–you can try day-time collection. Lay a trap of boards or shingles near the plants. The slugs will crawl under them during the night, and the next morning you (or your 5-year-old scientist) can crush them into oblivion. Some folks prefer prefer to place shallow containers filled with beer at ground level. Those little fellows will climb right in and drown. You can also scatter eggshells or diatomaceous earth around plants to pierce their bodies as they crawl towards their dinner but be careful: diatomaceous earth can hurt beneficial insects and must be reapplied after rain.
Skunks. That familiar smell that summer nights bring? Skunks aren’t really a pest for most of our gardens – they eat corn, for instance – but they make holes in the lawn when they hunt for grubs, and a skunked dog is not a pleasant one to be around. Skunks are nocturnal and they like to spend the days under porches or decks. If you suspect you have a family as house guests, the best prevention is exclusion. Seal off the openings to your deck or porch with 2-inch wire mesh that extends to the level of the deck or porch floor, 1 foot below the surface, and 6 to 9 inches at a right angle under the ground. To be sure that you haven’t walled in any brothers or sisters that decided to sleep in, leave open one entrance and sprinkle flour on the ground in front of it. Look for tracks after dark. That will mean the skunks are out of their den. Temporarily close the opening. Repeat the procedure the next night. Then close the opening permanently.
Grubs. If you have large brown patches in your lawn, grubs may be the culprit. You’re in luck: it’s the right time to prepare to eliminate this pest. First, you want to assess whether the population is large enough to warrant attention. From August until September you can do this by sampling: use a bulb planter or cup cutter; dig several holes about 10 feet apart in the affected areas and remove a core. Then place the soil on a piece of cardboard and count the number of “c”-shaped critters. Replace the core and water well. You can use the same technique by digging up about a square foot of sod with a shovel. If you have between 7 and 10 grubs per square foot, you’ll want to eradicate them. One biological solution is to use beneficial nematodes, which you can purchase from a garden center. If you want to use chemicals, late August is the time to apply them.
Powdery Mildew. White or gray spots on the leaves of your roses, phlox, azaleas, green beans? It could be powdery mildew, a fungal disease that comes with cool nights and warm days like we’ve been having. Although it’s unsightly, powdery mildew is not often fatal. Plants can lose up to 25% of their leaves without succumbing. If you can’t tolerate this ugliness in your garden, here are some remedies. Pick off the affected leaves. If you think the infection is severe, you can also use a fungicide when you first see the symptoms. Remove infected annuals from the garden at the end of the season, and dispose of them. Please remember that any diseased plants do not belong in your compost.
Tomato blights. What is happening to the tomatoes? As a result of the cool wet weather in June, there are many cases of late tomato blight and septoria, fungal diseases that affect tomatoes. Late tomato blight, which causes brown, water-soaked lesions on tomato leaves and stems, can be devastating. There is little that can be done to save the plant if the infection is severe. Cull out infected plants which can serve as an inoculum to healthy plants. Septoria is is not as dire as late blight. Though septoria lesions look similar to those of late blight, they are often grayish and are accompanied by yellow leaves. If you’re having trouble identifying the disease, bring a sample to Cornell Cooperative Extension or check out Vegetable MD Online. Tomato blights spread by spores which can rapidly infect other plants. What can you do? Pick off the affected leaves. This will control the infection, but it won’t stop it. You can also apply a multi-purpose fungicide to unaffected plants and continue to use it until you harvest the tomatoes. If possible, mulch plants with salt hay, and water at the base of the plants rather than overhead because splashing water on the leaves will promote the infection. Destroy the plants at the end of the season, and next year rotate your crops.
Please come by the Cornell Cooperative Extension of Westchester’s Master Gardener Booth at the Larchmont Farmers’ Market. We’ll be there to provide advice and answer your questions on Saturday, August 1 from 8:30 until 12:00.
Some Things to Do in July and early August:
- Continue to stake floppy plants like phlox, mallow and dahlias.
- Mow lawns regularly to keep grass height at 3 inches.
- Continue to aerate and moisten compost pile to speed decomposition.
- Deadhead annuals like marigolds, petunias, and geraniums as well as perennials like salvia, coreopsis, and daisies to encourage continuous bloom, and cut back any rampant growth.
- Remove any fallen leaves and debris that can harbor insect pests and disease organisms.
- Pinch back asters and chrysanthemums one last time.
- Finish deadheading rhododendrons and lilacs.