Pests and Diseases...
Adult Vine Weevil cannot fly but they crawl into greenhouses, they are usually
bought in on infected plants. All plants should be treated before they are introduced
into the greenhouse. They hide at soil level during daylight hours and each female
can lay up to a 1000 eggs, which hatch after two weeks. She lays her eggs in the soil
and soilless compost is ideal for them as it doesn't irritate the grubs as gritty soil does.
The fat, whitish larvae are 6-10mm long and are crescent shaped and legless. They
cause serious root damage, the grubs feed for 3 months before pupating.
There are various chemicals suggested for eradicating them, perhaps the best method
is watering with a systemic insecticide such as Provado Vine Weevil Killer.
Alternatively use a biological control based on Nematodes.
Whitefly are tiny white flies which lay their eggs on the underside of leaves and
as they are so tiny they are difficult to identify. They live on the underside of their
leaf, where they can extract nutrition from the plant. Control can be achieved by using
an insecticide twice weekly to kill the young as they hatch. A strict regime of spraying
and checking is essential to break the 'life cycle'.
Aphids are one of the commonest garden pests, greenfly and blackfly are aphids
and they suck the sap from plants. They arte attracvted to the young tender shoots,
they cause leaves to be distorted but are unlikely to kill a plant. Spray with a insecticide.
Red Spider Mite:
These tiny sap sucking pests are pale green with two dark spots on their back and it is only in autumn and winter that they turn orange-red. They thrive is hot dry conditions and if the temperature stays above 12 celsius they can breed all year round. The leaves and stems of plants become covered in a fine webbing. The upper surface of the leaf is mottled,while mites and eggs can be seen with a magnifying glass on the underside. Spray leaves with a systemic insecticide containing fatty acids or plant oils. You can help control them by improving air circulation and boosting levels of humidity by misting plants with tepid water and standing bowls of water in between plants. Dampening the greenhouse floor will help and you could also try releasing a preditory mite 'Phytoseiulus persmilis' onto your plants.
A fast moving green insect that is active in early spring. They suck sap from the shoot
tips of leaves and buds, the damage is noticeable weeks later when new leaves are
distorted and blackened on the edges. In the case of fuchsias these are usually killed off.
Spray with a systemic insecticide.
Is a fuzzy grey mould fungus which attacks new growth and freshly rooted Poor air circulation and fluctuating temperatures is ideal for it. Remove the causes to control it easily.
The first sign is a slight discolouration on the leaf, it develops spots with tan centres and
purple borders. the underside of the leaf will have rust coloured spots in clusters of
reddish orange pustules. When the pustules ripen they erupt and spread their spores into
the air infecting any fuchsias nearby. Prevention is better than cure, to prevent infection
spray with a systemic fungicide every 3-4 weeks. Once infected it is extremely difficult
to eradicate. Collect and distroy any infected leaves.
Sooty mould is a fungus that indicates the presence of sap sucking pests, it does not attack the plant directly but is unsightly and can reduce the plants vigour. Controlling pests will eliminate the problem.