Cleaning Up the Garden
This summer's cool, wet weather made it a difficult growing season for
the vegetable garden. Between the weather and a resident woodchuck,
what I got the most of was weeds! That means that clean-up will be
especially important this fall to reduce next year's diseases and insect
problems. To keep yourself motivated, remember that sanitation is one
of the most important steps you can take to insure that next year's
garden will be healthy.
Plant disease agents such as bacteria, fungi and viruses all remain alive, though dormant, during the winter months. By recognizing the places where these organisms hide, gardeners can often destroy them and prevent disease outbreaks the following spring.
Many fungi spend the winter on or in old leaves, fruit and other garden refuse. These fungi often form spares or other reproductive structures that remain alive even after the host plant has died.
The fungus that causes scab on apple trees and flowering crabapples forms a thick-walIed overwintering structure, called a perithecium, in fallen leaves. Other fungi such as Fusarium (causes wilting on plants) survive in refuse in the vegetative state or form small, spore-like structures called chlamydiospores. Blackspot, one of the best-known rose diseases, overwinters on fallen leaves and twigs and re-infests healthy plants in the spring. And cucumber and squash vines, cabbages, and the dried remains of tomato and bean plants are also likely to harbor fungi if left in the garden over the winter.
Insects, too, survive quite nicely in pIant debris over the winter months. Female moths of the common stalk borer lay their eggs in late summer on grass, weeds and plant refuse. A single female moth may lay up to 2,000 eggs, each of which will hatch into a borer the following spring. You won't notice it until healthy young plants begin looking sickly, or stems break off above ground.
A common problem in the flower garden is the iris borer, one of the most destructive insect pests of iris. Females lay their eggs on old iris leaves and other plant material in the fall. These eggs spend the winter on leaves and hatch in April or May. Cutting iris leaves back to a four-inch fan and removing other garden refuse during the fall can save iris plants from serious damage next season.
To avoid any or all of the above problems, plant debris should be carefully raked up and disposed of in the trash. Do not put refuse on your compost pile unless you know that it will reach 140 degrees Fahrenheit. It takes a fair amount of heat to kill these organisms, and you won't want to recycle them right back into the garden.
Keep in mind that insects and plant pathogens can survive on weeds as well as on garden plants. Many weeds serve as alternate hosts for insects and fungi, helping them to complete their life cycle. Destruction of these weeds removes a source of future troubles. And if you get them before they go to seed, you can cut down on next year's weed problem. Again, unless your compost pile reaches 140 degrees Fahrenheit, you'll want to dispose of weeds with seed pods elsewhere.
While you're cleaning out the garden, take note of which varieties did well and which did not. That information is always helpful in January when it's time to order seed.
If you can fit it in before the end of September, turn the soil and plant a cover crop. It will cut down on erosion, promote soil microorganism activity and add organic matter to the soil in the spring. And think what a treat it will be next spring to look at a prepared garden plot rather than at last year's leftovers.
For additonal information on maintaining a successful garden download: 10 Easy Steps to Prevent Common Garden Diseases
Call the UNH Cooperative Extension's Family, Home & Garden Education Center 's Info-Line toll-free at 1-877-3984769 for "Practical Solutions to Everyday Questions." Trained volunteers are available to answer your questions Monday through Friday from 9 am to 2 pm .
By Margaret Hagen, Extension Educator University of New Hampshire Cooperative Extension