We forget the challenges of cutworms in the early spring and the potato beetle we faced in the summer. In winter, we neglect the pests, imagining them to have just gone away. In reality, they’re asleep too. The pests that we encountered over the summer have gone into hibernation or diapause not far from the food source they enjoyed over this past season. At this stage they are vulnerable, which gives the gardener an advantage and the opportunity to implement controls.
Winter management strategies are not an instant solution to the problems in your garden but they will give you a head start on the season to come. This approach works with the natural system, this is what we are aiming for – long term effects that will continue to work after the initial implementation and require little to no maintenance.
Knowledge is key, so let’s refresh our memories of which pests were in the garden so we may address the problems over the winter to give our gardens a better chance this spring. Who attacked your plants this past season and where are they now?
|Pest||Host Plants||Damage||Overwintering Sites|
|Aphids||A wide range of annuals, perennials, fruit and vegetables found throughout North America||Aphids are sap sucking insects that will cause foliage to distort and leaves to eventually drop. Aphids excrete a substance called honey dew which encourages black sooty mold reducing photosynthesis and weakens the plant.||Found throughout North America. Adult Aphids overwinter on host plants in and around the garden. Host weeds include; Thistle, field bindweed, lambsquarters, grasses and mustard. In some cases aphids overwinter as eggs on the terminals of fruit trees.|
|Potato Beetle||Potatoes, tomatoes, eggplant, petunias.||Beetles will defoliate plants very quickly, ultimately killing the plant.||In the soil as adults in most states and Canada. The adults are usually found around the edges of fields and wooded areas under brush and leaf debris.|
|Cutworm||Seedlings and starts of vegetables and annuals. Found Throughout N. America||Cutworms are present in the early season feeding on new transplants or seedlings. They chew through stems at ground level. Many vegetable starts can be devoured in a night. The destruction resembling a small clear-cut forest.||On the Pacific Coast and in Southern U.S. Cutworms are found as caterpillars in the soil of raised beds, gardens, pastures and weedy areas. In colder climates they will migrate in as adults as the temperatures warm.|
|Cabbage Maggot||Cabbage family crops; Cabbage, Broccoli, Cauliflower, mustards and radishes||Maggots tunnel in roots causing plants to pale and wilt. This can kill the plants directly or provide opportunity for other disease organisms to move in.||As pupae in the soil close to plants in the cabbage family and related weeds. Throughout the northern U.S. And Canada.|
|Mexican Bean Beetle||Cowpeas, lima beans, snap beans, soybeans. Found East of the Mississippi as well as Arizona, Utah and Nebraska||Adults and juveniles will feed on the underside of leaves causing a lacy appearance and ultimately defoliation.||As adults under brush and leaves in wooded areas adjoining fields/gardens and in the soybean refuse. Found in most States east of the Rocky Mountains.|
Don't throw out the good with the bad.
The allies of your garden such as ladybugs, syrphid flies, ground beetles and parasitic wasps will also stick close to a successful environment. We want to encourage their presence. When you are implementing controls of any kind the aim should be BALANCE not elimination. Balance is achieved through diversity and established thresholds. Diversity means having a broad spectrum of plant variety and insect species.
Thresholds are a predetermined level of pests that we can manage without severely impacting a crop .For example; a low level of aphids is necessary to keep the ladybugs and other aphid predators active in your garden. We need to conduct our garden cleanup with this in mind, approaching the activity with all aspects of the natural system considered.
Follow these guidelines to ensure that you are addressing the problem while not eliminating your allies in the garden.
Winter Control Guidelines For Beneficial Insects:
- Leave healthy, standing, hollow stemmed plants such as dill, amaranth and elderberry as refuge spots for ladybugs and solitary bees.
- Rocks and logs strategically placed in the garden for aesthetic effect make excellent refuge for predatory beetles.
- Wait until Spring to cut back ornamental grasses. These perennials are ideal locations for overwintering bumblebees.
- Create small piles of maple leaves, brush or untreated grass clippings for ground beetles and other terrestrial predators.
Add fresh compost to beds to boost beneficial microbes and predatory mites.
Winter Control Guidelines For Pest Control:
- Inspect and remove plant material in the garden where known pests existed. Check the leaves of kale, cabbages and brussel sprouts for aphids. If found, remove material and dispose into garbage. Not in compost pile.
- Pull any remaining carrots, onions and rutabagas. Check for root maggots and dispose of those in the garbage.
- In asparagus patches, remove remaining plant debris where asparagus beetle or aphids are overwintering.
- Turn the soil lightly to expose any soil dwelling cutworms, potato beetle and grubs to the birds. You can even go so far as to scatter bird seed to encourage types that eat both insects and seed.
- Collect any Ground beetles and Rove beetles and gently transport them to the composter and place under the material.
- Clean greenhouse structure with mild bleach solution to kill any fungus spores. If structure is wood follow up bleach solution with horticultural oil painted onto all exposed wood. This will suffocate the spidermite, thrips and other tiny pests who are hibernating in the cracks and crevices.
Education is the key
When Spring arrives and the first of the plants start to bloom, get out there and have a look around. The more you know the better equipped you will be. Check for plants that are struggling, these will be the first to be hit by pests. Notice which plants are thriving. What is it that makes them so successful? Learn which insects inhabit your garden to determine what you may be missing and take the steps to encourage the missing ones in.
Educating yourself leads to a greater level of intimacy with your garden and a clearer understanding of how it all works. Learning today prepares you for tomorrow.
Colorado State University
University of Florida
Rodales Organic Life