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Diseases
SHOOTS AND LEAVES AND FLOWERS
Powdery Mildew. A fungal disease that attacks both upper and lower sides of the leaves and occasionally, the stems
WHAT TO LOOK FOR: White to grey powdery spots form on the leaves. If allowed to progress unchecked, leaf death will occur and eventually the plant will die. Canadian Xpress PMT is non toxic and will control Powdery Mildew.
Botrytis. A very common fungal disease that often attacks flowers but also attacks stems and leaves, especially where the plant tissue has been damaged. The optimum conditions for germination of spores is a temperature of around 15-20oC and 8-12 hours of very high humidity. In practice, it most often occurs in the last stage of the flowering period.
WHAT TO LOOK FOR: Grey mould on flower heads. They become slimy and disintegrate in severe cases. Soft rot on leaves is usually also Botrytis. If this occurs then the plants are too wet and are probably lacking in ventilation.Other Fungal Diseases. A number of other fungal diseases may attack the plants. The symptoms are generally similar with brown spots, either regular or irregular, on the leaves. They may be flat or raised. If these symptoms appear and then seem to spread from one plant to another you may suspect a disease.
ROOTS
Pythium. A fungal disease that attacks the roots. The disease organism can be found in water supplies, irrigation lines and soil. It is very common and is a worldwide problem.
WHAT TO LOOK FOR: The tips of the plants wilting after the lights come on or when the plant is exposed to sunlight. The plants will recover at night or when the lights go off. As the disease progresses, the wilting becomes permanent and widespread. The plant stops growing and may die. Virulence varies widely from hardly noticeable to swift and sudden plant death. It is important to maintain hygiene and treat nutrient solutions on a regular basis. Use Regen-A-Root and Wiltguard together.
Phytophthora. Similar to Pythium and the treatment is the same. Use Regen-A-Root and Wiltguard together.
Rhizoctonia. A fungal disease that attacks the stem at ground level
WHAT TO LOOK FOR: A soft rot of the stem at soil level. Keep the drippers from wetting the stem every time the plant is irrigated.Verticillium. A fungal disease of the vascular system which enters the plant through the roots. The first symtoms are wilting often of just one side of the plant first, followed by wilting of the whole plant then death. On cutting through the stem, the vascular system can be seen to be a brown colour.