Slugs and snails are a nuisance for most gardeners, but simple preventive treatment, such as erecting barriers, encouraging predators, and using biological controls, can significantly reduce attacks in gardens. Tackle other pests with similar organic controls and guards to reduce the need for chemicals.
Slugs and snails
Although these are annoying plant pests, much of their activity, such as devouring rotting vegetation, is actually beneficial. Unfortunately, they do not discriminate and are equally happy to chomp through desirable plants and crops.
These nocturnal nibblers have rasping mouthparts, and chew the margins of leaves and petals, as well as leaving holes in them. They also strip off chunks of stem, causing young plants to collapse, and graze the skin and peel of fruit and vegetables.
Seedlings and any juicy young shoots of established plants, flower and leaf buds, and newly unfurled foliage are particularly vulnerable. Snails can climb up walls and tall plants to reach their food, while some slugs live underground.
Check under and around the rims of pots, beneath ledges, in piles of rocks or logs, and on evergreen shrubs where slugs and snails roost, and pick them off. Beer traps will lure them in at night. Slugs and snails are also deterred by copper strips, which give them an electric shock when they pass over them, and cloches made from plastic bottles. If all else fails, sprinkle pellets sparingly around key plants.
These pests are commonly known as greenfly, although other colors exist and some have a woolly wax coating. Aphid species number over 4,000 worldwide, and many favor specific plants. They reproduce rapidly in spring and summer.
Signs of attack
Shriveled and distorted shoots, leaves, and flowers are the main signs of aphid attacks. You may also see a residue of a sticky honeydew excretion, which can lead to black sooty mold. Also look for aphids’ white discarded skins, which they shed as they grow.
Aphids transmit viruses, and yellow mottling and color streaks in leaves and flowers indicate possible infection. These tiny insects give birth to live young that immediately start feeding, so soft plant tips rapidly become infested. Pinch off heavily affected shoots or blast them with water from a hosepipe.
Birds and small mammals
Mice and other rodents dig up spring-sown seeds in the kitchen garden, and in autumn munch on ripening fruits and gnaw newly planted bulbs. Some birds are also a nuisance, pecking flowers, pulling up seedlings, eating brassicas, and stealing fruit.
Rabbits, squirrels, and pigeons can lay waste to newly planted beds, borders, and pots. To avoid scenes with plants ruined, erect barriers or netting, or cover seedlings and pots of bulbs with chicken wire. To prevent cats from scratching in the finely tilled soil of seed beds, lay thorny twigs across the surface, or insert short bamboo canes between crops or flowers. Sow large seeds, such as peas and beans, in pots away from hungry mice, and protect trees and shrubs with rabbit guards.
Tips: Biological control
Slugs, vine weevils, chafer grubs, and crane fly larvae can all be controlled with microscopic nematode worms that kill the pests without harming the environment. Mix the nematodes with water and apply at specific times of year, following the supplier’s instructions. Treatments may need to be repeated. You can buy nematodes to control a range of pests on the internet or via mail-order companies.