BOTRYTIS

This common killer of promising plants occurs mainly in damp, crowded conditions.

Symptoms

The first signs are wilting stems and falling leaves, similar to the effects of over-watering. In fact over-watering is often a primary cause of this problem.

On further examination a grey furry mould may be seen on fallen leaves and around the base of the plant stems. A brown stain can often be seen travelling up the stems from compost level.  Leaves on such stems are unlikely to survive.

Treatment

Remedies include providing more space per plant; better ventilation with the greenhouse door open all day in all but the coldest weather, to allow a good circulation of air; and more careful watering. Infected plants can be pruned to remove the affected stems and will often make a full recovery. 

Compost surface should be kept clear of all decaying matter and a fungicide applied. Like many other problems botrytis is largely due to poor hygiene and greenhouse management.