DiseasehighJun–Oct

Verticillium wilt

Verticillium dahliae

This description was machine-translated.

How to spot it

Verticillium wilt is a soil borne fungal disease that enters through the roots and blocks the plant's vascular tissue. Because water and nutrients can no longer get through, individual shoots or leaves wilt, often on one side only, and no longer recover overnight. Typical is a brown to greenish black discolouration in the wood, which you can see when you cut open an affected shoot. On maple and smoke bush a whole branch often dies back suddenly while the rest is still green. On tomato, aubergine, pepper and strawberry the plant struggles in summer heat and later collapses. The fungus forms resting bodies that survive ten years and more in the soil, which is why it keeps coming back on infected ground wherever susceptible crops are grown. The symptoms show above all in the warm summer, from June into October.

Prevention

No spray helps against verticillium wilt, because the fungus sits in the soil and inside the plant. So rely on prevention and a healthy site. Dig out infected plants with as much of the roots as possible and put them in the residual waste, not on the compost, so that the resting bodies do not spread further. On contaminated beds, do not follow with susceptible crops such as tomato, aubergine, strawberry or dahlia for several years; instead put in a wide rotation with grasses, cereals or alliums. Where possible choose resistant or tolerant varieties, and among woody plants pick resilient species. Keep the plants strong through an even water supply without waterlogging and moderate feeding, because stressed plants fall ill more easily. Avoid root damage when hoeing and transplanting, work in compost and mulch for an active soil life, and clean tools and shoes before you move from an infected bed to a healthy one.