Gardening
for Your Watershed – March
2004
---------------------------------------------------------------------------
Topics in this issue:
* Getting into the Swing of Spring
* Pest of the Month: Crane Fly
* Free Lawn Evaluation for Crane Fly
---------------------------------------------------------------------------
Getting into the Swing of Spring
---------------------------------------------------------------------------
While it’s easy to get excited about gardening on a warm summer day, the damp days make early spring a much better time to plant perennials. Transplants do better with cold days and cold soils. And the frequent spring rains will help keep new plants well-watered, saving you some time and boosting root development.
If you neglected weeding over the last several months, it’s likely that winter annuals have infested your flower and vegetable beds. Perennial weeds like dandelions are also coming out of dormancy. Take some time to pull them out while they’re relatively small, and you may be able to avoid using herbicides later.
Now is also the time to pay some attention to your lawn. Overseeding now will help new grass become established before the dry season begins. It’s also a good time to fertilize, if your turf needs additional nutrients.
---------------------------------------------------------------------------
Pest of the Month: Crane Fly
---------------------------------------------------------------------------
Crane flies are often blamed for lawn problems. In 1999, homeowners around
the Puget Sound spent about $13 million on home use pesticides to control
crane flies.
But these insects, which look like giant mosquitoes bumbling around your porch light in late summer, may not actually do any damage to your lawn. Since 2001, WSU Master Gardeners have sampled over 150 lawns in the Lake Whatcom watershed and only found one lawn that had enough crane fly larvae to be even considered a potential pest problem.
Todd Murray, the Integrated Pest Management project manager at the local WSU Extension office, believes that most pesticide applications for crane fly in the watershed, and in the county as a whole, are probably unnecessary. “Judging by our study, crane fly doesn’t seem to be a problem for most lawns,” he says.
The two chemicals most commonly used by homeowners for crane flies, chlorpyrifos (also known as dursban) and diazinon, have been detected in streams throughout western Washington. (Both are being phased out of home use.) The U.S. Environmental Protection Agency has determined that diazinon and chlorpyrifos in drinking water is primarily due to use by homeowners.
A 1999 Department of Ecology study did not detect any insecticides in Lake Whatcom, the drinking water supply for half of Whatcom County’s residents, but preventing them from entering the lake is still a priority for local government agencies.
Adult crane flies lay eggs in the late summer. The eggs develop into larvae, called leatherjackets for their leathery appearance, which start feeding on turf roots in the early spring. They are mostly inactive by June, and emerge as adults in August and September.
Since this is the season when crane flies are feeding on your lawn, now is the right time to go out and survey your lawn for larvae and, if necessary, to decide how to manage them.
Decision making:
• Count your leatherjackets. Using a shovel or spade, cut a 6” x 6” square of sod and gently peel it back. Count the number of larvae and multiply by four to get the number of larvae per square foot. Most lawns can tolerate up to 25 larvae per square foot; many can withstand at least 40. WSU Extension traditionally recommends treatment if your lawn has 25-50 larvae per square foot.
• Assess the state of your lawn. Does it have good drainage, does it get enough nutrients, do you mow it to the correct height? A healthy lawn can absorb more damage from crane flies than an unhealthy one.
• Learn about the birds and the bees. If you decide to treat with a pesticide, avoid using one that’s toxic to other insects and birds (who love to eat leatherjackets).
---------------------------------------------------------------------------
Free Lawn Evaluation for Crane Fly
---------------------------------------------------------------------------
In March, WSU Master
Gardeners will evaluate lawns throughout the county for crane fly problems.
If you’re interested in having your lawn
evaluated, sign up for your free evaluation at http://whatcom.wsu.edu/cranefly or
by calling 360/676-6736. Hurry because the survey is limited to 100 lawns!
=============================
This newsletter
is produced by Whatcom County Extension. To subscribe or unsubscribe,
or to make comments and suggestions, please contact Scarlet
Tang or
360/676-6736.
