Tent Caterpillars in Your Garden
Populations of tent caterpillars are usually held in check by winters cold, enough to kill many of the egg masses laid in the fall. But a mild winter may mean a tent caterpillar heyday in the spring. There are things you can do, however, to help mitigate the damage and mess they make out of your plants. The larval stages of several moths and butterflies create tents, but the controls for these caterpillars are all the same.
The tent caterpillar life cycle begins in the fall with adults laying eggs on branch ends of plant hosts that leaf out in the spring and become food for the caterpillars. The masses of hundreds of eggs are laid in a flat viscous material that dries hard and is camouflaged with the bark of the plant on which they are deposited. It takes some hunting to find these masses, but once you develop an“eye”for them, many can be easily found, removed manually, and disposed of.
When caterpillars hatch, they set up a tent of webbing. Each evening, they return to this tent for protection against the weather and predators. This is the best time to control them by removing the portion of the branch that contains the tent and dispose of it offsite.
For shrubs and trees that have branches out of reach, a bacterium Bacillus thurigensis (Bt) can be applied to foliage early in the plant’s spring growth – ideally before the caterpillars hatch. Once caterpillars ingest the bacteria-coated foliage, they die in 24 to 48 hours. However, once caterpillars reach ¾ inch in length, the Bt does not seem to have the same amount of control.
Parasitic wasps and other natural enemies of the tent caterpillars can be used as well. More potent chemicals are available but are not as safe for beneficial insects and animals. Additional questions? Go to https://extension.wsu.edu/whatcom/hg/hg-plant-clinic/
- Although spring blooming bulbs appear in stores this month, wait to plant them in late October, early November.
- Don’t pick your ornamental gourds or winter squash too early. Wait until the stems turn brown and the vines start dying.
- Throughout the fall, keep prunings, fruit and other debris picked up so they don’t provide a home for pests and diseases
- Early fall is a good time for seeding a new lawn or bare patches due to less weed competition, mild temperatures and fall rains.
Plant a Cover Crop
Cover crops serve several valuable functions in the home vegetable garden. The plants prevent erosion from winter rains and reduce the ability of weeds to grow. They also help the soil retain nutrients for next season’s crops and can even fix nitrogen if you use legumes like crimson clover or field peas. Most commonly planted by gardeners in the fall, cold hardy cover crops serve as ‘green manure’, when cut and turned into the soil in the spring to decompose and increase organic matter. However, cold sensitive cover crops can be used in warmer months to suppress weed growth in garden space that is not planted in the current year. Planning for the use of cover crops is important – to determine the right time for good germination and which crop best suits your needs and the size of your gardening space. Go to these two WSU fact sheets for more detailed information:
- Sow seeds of cool season leafy greens – lettuce, spinach, kale and chard – this month for harvest this fall.
- Wait to transplant any ornamental shrubs or trees until after September. This is a very stressful time and doing so may result in the plant’s death by spring.
- Powdery mildew is likely to appear on roses, apples, grapes, lilacs and annuals. A fungicide will protect new growth but will not affect the mildew already there.
- Avoid watering your tomatoes from above as moisture on the leaves can encourage a fungus known as late blight. Consider a plan to grow them under cover next year to protect them from rain as well.
Make Every Drip Count
As our PNW summers grow increasingly dry, it’s time to up your efforts to conserve water and make every drip count. The first rule is to water plants only when they need it and use water-miser methods. Use drip irrigation or soaker hoses and avoid sprinklers as they have significant water loss due to evaporation. Be sure to position the water devices you use to prevent water runoff into walkways, storm gutters or the street. In addition, for shrubs, trees and the lawn, remember the mantra to water deep and less often. Plant selection is key. Select drought-tolerant lawn grasses – or let your lawn brown out. Include more water-frugal plants, especially natives that are suited to our climate. And be sure to keep your beds mulched to retain soil moisture and remove weeds that steal water from your plants. Finally, consider ways to keep water on your lawn. Add rain barrels to collect rainwater for watering plants. Design a rain garden or develop a swale to retain water in your soil and prevent runoff. Investigate your local codes regarding the use of grey water.
- For the rest of the season, only feed your roses, flowering annuals and veggies.
- The yield of beans and cucumbers is improved by watering a few times with a low-nitrogen liquid fertilizer.
- Continue to deadhead your flowering plants and harvest your veggies when they are in prime condition.
- Let your tomatoes ripen on the vine for best flavor – except later in the year when a frost is predicted.