Page 28 - ALG Issue 1 2022

Avoiding pests
and diseases when
sowing seeds and
transplanting
The most important point to note when sowing seeds is to keep your tools and equipment clean and to use fresh seed sowing compost that is free draining. A number of compost borne pathogens can cause a condition called “damping off” where seedlings collapse and decay; white fungus may also be visible. It is a particular problem when sowing under glass with high humidity and poor air circulation but can also affect seeds sown outdoors. Seeds sown directly into wet, cold soil are especially vulnerable to damping off. Avoid sowing seeds too thickly.
Andrew Tokely from Kings Seeds advises charging the seed tray or pot with water before you start; you should not need to water again until you transplant; use tap water not butt-water as fungus can survive in butt water. If you are using peat-free compost, be careful to not over-water
- the medium may appear dry on the surface but be moist underneath. Once the seedlings appear, remove from the propagator into a light well- ventilated spot.
Fungus gnats are common on house plants and can affect seedlings grown under glass. The adult flies are 3-4mm long and greyish brown in colour; they can be seen flying around the surface of the compost. They do not harm the plants, but the larvae can feed on seedling roots. It is best to avoid fungus gnats by using fresh seed compost and keeping a good hygiene regime around propagation areas. Fungus gnats are not usually a problem for outdoor sown seeds.
Seeds sown directly into your plot are more likely to come under attack from pests rather than diseases. Mice and birds are partial to pea and bean seeds and slugs like nothing better than a lush young seedling or transplant. Physical barriers such as netting can restrict access to your crops from the birds and wire over seed drills discourages mice. Some gardeners use spiky leaves such as holly or gorse.
Using nematodes in your seed bed will reduce slug numbers in that area; these microscopic organisms infect slugs and kill them. You
can pick slugs by hand at night; also beer traps and bran are popular methods. Slug pellets are a last resort and should be used with moderation. Young transplants can be protected by individual cloches – recycled water bottles with the bottom cut off work well. Aphids also like soft young growth but they can be removed by hand or dislodged by a water spray.
Thinning out your carrot seedlings can attract carrot fly. Damage can be avoided by always using a rotation system, sowing thinly, and covering the crop with enviro-mesh. Cabbage root fly will attack brassicas soon after transplanting – brassica collars around the small plants means that the eggs are laid 15cms away from the roots, too far away to be a problem. Flea beetles can also be a problem and wipe out on seedlings in the brassica family such as cabbage, broccoli, sprouts, turnip, radish, and salad rocket. The beetles can be seen jumping away from the crop and the leaves will be riddled with small holes. The adult beetles over- winter in leaf litter so clean up any piles near to your growing area and remove weeds such as shepherds’ purse and hairy bittercress that are also susceptible to attack. Insect-proof mesh is the best way to protect against attack.
Encouraging natural predators such as birds, frogs and ground beetles into your plot will reduce damage from many pests.