The first is a pre-emergence rot, which can be seen as failure of plants to emerge. Both symptoms are usually found in patches and the area affected can increase rapidly, particularly during cold wet periods. Damping-off is caused by various species of Pythium, Fusarium and Rhizoctonia. These fungi are all common soil inhabitants which cause damage generally under conditions that are less than ideal for seed germination and seedling growth. No control measures are available.
Infection can cause general stunting of plants and severe yield loss.
The only economic control measure is by rotation with non-host plants such as grasses. Bacterial wilt Bacterial wilt can cause serious losses in the eastern States but has not yet appeared in Western Australia. Symptoms include yellow-green foliage and stunted plants. Leaf margins are often 'cupped' or curled upwards. Symptoms can appear on single plants scattered throughout the stand or on patches of plants.