Orchid Bacteria, Orchid Virus and Useful Insects for Orchids
These are, of course, invisible to the naked eye and by the time symptoms are observed it is usually too late to do anything.
Fortunately, they are very rare on windowsills or in conservatories.
Symptoms: slimy, porridge-like, moist patches on leaves and bulbs; yellow, glassy-looking tissue.
Causes: infestation through water; wind-borne or carried inor from other plants.
Remedy: generally in vain. If infestation is mild, isolate the plant, remove all infested leaves and water frequently withtea or a protection spray containing etheric oils.
Ask for advice from orchid experts in the case of rare or very precious plants.
Orchid raisers dread viral diseases among their plants.and are particularly at risk. Fortunately, viral diseases, like bacterial diseases, are fairly rare.
Symptoms: crippled growth and discoloration in flowers; small black and brown spots; striations on the leaves; purplish spots onleaves.
Causes: infection through poor hygiene or ventilation or via insects.
Remedy: isolate infested plants at once and wait for a few days. Not every deformed flower or spotty leaf is infected with a virus. If infestation progresses rapidly, throw the plant away.
The following problems with pests can be combated by employing useful insects:
- predatory mites to control spider mites
- lacewings and gall midges to control aphids
- ichneumon flies to combat white fly.
This practice is particularly successful in greenhouses, conservatories and windows conatining many plants. Useful insects can sometimes be obtained from garden centres and seed merchants.
Garlic tea to control fungi and bacteria
Crush one garlic clove, add it to 1 litre (1/2 pt) of water and bring to the boil. Allow it to cool and use as a preventive measure once a week by spraying it on plants or watering sick plants with the brew. Garlic contains fungicidal substances and antibacterial compounds which are still effective even when extremely diluted.
The plastic bag trick
The easiest, cheapest and most harmless way to get rid of spider mites is to create a “sauna”. Water the infested plants well, then pour away any excess water. Place the pot inside a large, transparent plastic bag. Tie up the neck of the bag and leave the plant inside for one or two days. Use bags from dry cleaners for very tallor Cymbidium plants.
If you are not quite certain about your own diagnosis of a problem, you can always turn for advice to your local garden centre or phone your nearest orchid nursery or society.