The more healthy a plant is, the more resistant it will be to pest and disease attack. Insect pests are attracted to the weakest, most stressed plants in a crop. Improving soil structure and fertility with organic matter makes for healthier soil and this in turn makes for strong, healthy crops – and minimal crop damage. Organic gardening techniques also produce plants that grow steadily rather than rapidly as is the case with chemical fertilizers. The plants therefore do not become soft and sappy and prone to attack.
Compost and mulches retain soil moisture so that plants are not water -stressed on hot days. It is also important to water in response to the needs of the plant. Plants that are regularly wilted and stressed, as well as ones that are overwatered, are much more susceptible to attack by insects.
A plant in the wrong position is also liable to be attacked. We all succumb to the temptation to buy and plant things that are marginal for our climate, do poorly in our type of soil, or need conditions we cannot offer like wind protection or an open sunny site. But plants that survive these impulsive gardener moments will always remain more vulnerable to pests and diseases.
And it pays to plant crops at the optimal time. Plants may well survive being planted too early or too late, but they will never thrive as they should.
You can also choose cultivars that have been selected for resistance. Many strains of vegetables are able to resist attack to some degree. If you garden in an area regularly affected by a particular pest or disease, some research and careful selection will reward you with stronger, less susceptible plants. Neighborhood plant nurseries can be invaluable sources of good advice.
Good garden housekeeping
Many diseases and plant pests can be eliminated from the garden simply by good housekeeping practices. All garden wastes, including spent crops, should be composted. If material is infected, it should be placed in the centre of the compost heap where the high temperatures reached will kill all spores. Infected woody prunings, however, should be burned, if possible.
Viral diseases are passed on mainly by sap-sucking insects. As soon as a virus infected plant is detected, it should be removed and added to an activated compost heap. Or better yet, burn any diseased plant material if you can.
Dealing with garden problems as they arise will ensure fewer pests and disease problems. A thorough clean-up at the end of summer or early in autumn can do much to prevent pests and diseases in the next growing season. Digging the garden over at this stage not only aerates the soil but can also expose overwintering larvae of various pests. Make sure that no vegetables are left on the ground. Any mummified vegetables should be burned if possible. After pruning deciduous trees, check for the presence of borer and destroy any you find by poking a wire into any holes. Use a wire brush to remove any loose bark, which often shelters overwintering pests.
Don’t get mad, get clever
Combating slugs and snails
If your garden is small enough, picking off slugs and snails every night will reduce the damage done by them. Just squash them under your shoe or boot. Beer in a saucer is another effective trap – you will need to empty it every morning. Soft mollusc bodies don’t like crawling over scratchy materials such as crushed eggshells, slaked lime, salt or sawdust. Snails and slugs will also not cross copper because it gives out a weak electrical charge; trees can be protected with a band of copper, but allow room for a little growth.
Barriers and traps
Among the most useful advances in recent times has been the development of finely woven, transparent cloths to protect vegetables and fruit trees. These are woven to allow water and maximum light and air through while excluding insect pests. Floating row covers are ideal for the vegetable garden.
Other relatively newly developed barriers are sticky, non-drying glues that trap insects migrating up the stem or truck. The glue is placed on a paper collar around the base of the plant. A simple non-sticky collar can be made from a cardboard cup with the base cut out. Placed around the base of seedling, this is sufficient to protect it from cutworm damage.
In some areas, carrot fly is a real problem. But the female fly needs to hover low over the crop in order to detect the odour of carrots. Erecting a simple, temporary barrier fence of hessian (burlap) around the row will force the female fly to hover too high to detect the scent.
