Here is a short list of the pests and diseases likely to be encountered when growing vegetables. There are many more associated with particular plants which are described in detail in the many excellent books specifically on vegetable gardening that are available today.
Roots and tubers eaten. Leatherjackets, millipedes, slugs, wood-lice. Cover with crop-protection sheet and mulch soil with woven sheet mulching. Trap slugs in jam jars half full of stale beer.
Or, Cutworms, chafer grubs, vine weevil grubs, wireworms, cabbage root fly, carrot fly, onion fly, swift moth caterpillars. Treat soil with a soil insecticide and keep crops covered with crop protection sheeting.
Holes and notches in leaves. Earwigs, pea and bean weevils, caterpillars, flea beetles, capsid bugs. Cover with crop-protection fleece. Remove large pests by hand.
Or, Slugs and snails. Trap as above.
Or, Pigeons and other birds. Cover the area.
Black, green, grey insects in clusters on leaves, stems, roots. Aphids. Spray with horticultural soft soap or hand pick; cover with crop-protection fleece.
White, moth-like insects on leaves. Brassica whitefly. Cover crop.
Base of stems black, shrunken or rotten. One of a number of basal stem rots associated with poor growing conditions – wet, cold soil or compost and overcrowding. There is no cure, and affected plants should be removed. In young seedlings a similar condition is caused in the same way and is known as damping off or black leg.
Blistered or tunnelled leaves. Leaf miner. Unlikely to be serious.
Brown spots on leaves and pods. Leaf spots. Indicates poor growing conditions. Remove affected leaves or plants if infection serious. Try to improve conditions for subsequent crops.
Yellowing between veins. Magnesium or manganese deficiency. Can indicate a too high pH. Treat area with Epsom salts or sequestrene and check pH before resowing the area.
Club root disease. Serious disease of cabbage family. There is no cure so pull up and burn plants. Do not grow brassicas on that land for several years. Raise young plants in individual containers and plant deeply.
Gall weevil. In this case there will be a maggot inside the swelling. Not serious. No treatment necessary.
Eelworm. No cure. Do not grow crop affected on that land for at least 6 years.
Split, distorted or fanged roots in root crops. Irregular watering. Try to ensure consistent water supply.
Or, Fresh manure in the soil. Do not plant on newly manured ground.
Or, Stones. Remove as many large ones as possible from the ground.
Root rots. Several different diseases cause rots in vegetable fibrous roots, root crops, and bulbs such as onions. There is no cure and crops so affected should not be grown on the same land for several years. Rotting can also occur in heavy, cold, waterlogged soils so try to improve such soils before using for vegetables.
White powdery coating on leaves, some distortion. Powdery mildew. Remove badly affected plants.
Yellowing leaves with white furry fungus beneath. Downy mildew. Remove affected plants.
Mottled leaves. Possibly virus. Remove affected plants and burn. Protect against aphids which spread viruses from plant to plant.
Poor brassica crops – heartless cabbages, sprouts with loose, ‘blown’ rosettes instead of tight buttons, cauliflowers with loose, small or missing ‘curd’ (the white part). This is usually caused by insufficient firming and the plants blowing about in the wind. Brassicas should always be planted in firm soil and in windy districts sprouts should be individually staked. Drought, shade and impoverished soils can also cause these conditions so always plant in a sunny spot, fertilize well with a balanced feed, and give plenty of water in dry spells.