Gardening Pests and Diseases

Aphids
Colonies of small round-bodied insects suck the sap from leaves and distort plant growth. They excrete a sticky honeydew on which sooty moulds grow, and can also spread viruses. Aphids, which are mostly wingless, may be black, green, pink, red, yellow or variously coloured.

Danger Period
Spring and early summer in the open, but any time of the year under glass or indoors.

Treatment
Outdoors or in a greenhouse, spray thoroughly with systemic insecticide such as heptenophos, or with non-systemic insecticides such as malathion, pirimicarb, fenitrothion or derris. Inside the house, use derris only. Encourage predators such as beetles, ladybirds (you can get from some garden centres), bluetits, hoverflies and praying mantis.

If I ever find a praying mantis on my terrace I pick him up and place on my roses or trees so he can eat all the baddies :)

Scale Insects
Particulalry troublesome on greenhouse and houseplants, but also ornamental shrubs, trees and fruit grown outside.

Recognition
Brown, yellow or white scales - flat or oval - mainly on the underside of leaves and clustered alongside the veins and on the stems

Danger Period
Late spring or early summer outdoors, but at any time of the year when under glass

Treatment
Spray with pirimiphos-methyl, heptenophos & permethrin, or malathion three times at twp-week intervals. Alternatively, gently remove scales by hand or with a soft toothbrush, or spray insecticidal soap.

If you have any bark breaking then you need to cut out the dead wood, remove loose bark to reveal a clean wound. Feed, mulch and water the tree properly and the wound should heal naturally.

Do not have irrigation pipes close to the roots, let the water run to the plant rather than right at it!

Do you have any spotting on the leaves of the tree?
Try watering during dry spells and muching the trees, this is common after a drought.

Fruit - Drop
If your fruit has dropped from your tree early then this would be a classic sign that pollinators are not in your garden, feed, mulch and water the tree. If you are experiencing fruit drop in cold seasons then this means poor pollination and nothing can be done until the following season.

Honey Fungus
This can affect most trees and shrubs. Common among rotting tree stumps, some herbaceous perennials and some bulbs.

Recognition
Toad stools at soil level at the base of the trunk. White fan-shaped growths of fungus occur beneath the bark of roots and at soil level. Black ´bootlace´threads on diseased roots spread infection.

Danger Period
Autumn

Treatment
Destroy dead or dying plants and as many roots as possible. Sterilise the soil with a phenolic compund such as Armillatox. The ´bootlaces´do not necessarily mean disaster. Many species of the fungus are not invasive.

Nitrogen Deficiency
All types, but most commonly fruit trees and vegetables.

Recognition
The young leaves turn pale yellow-green, and later develop yellow, red or purple tints. the plants are small, stunted and lack vigour.

Danger Period
Growing season

Treatment
Use nitrogenous fetiliser such as blood, fish and bone or sulphate of ammonia in spring. Improve soil structure and fertility generally. For a quick result, water with a liquid feed or apply a nitrogen-rich foliar feed. A temporary definciency can arise in cold weather, but it will disappear as the soil warms up.

If you have advice where you can purchase these fertilisers or treatments, please let us know so we can forward to our readers

Thanks