Damping Off Control

Symptoms

In the nursery, seeds may rot before emerging, called pre emergence damping off. After emergence, young seedlings develop a water soaked, soft, brown rotting at the base of the stem near the soil, the stem becomes thin and weak, and the seedling topples over and dies, called post emergence damping off. The collapse usually appears in circular patches that spread outward, and is worst in crowded, overwatered, poorly drained nurseries.

Damage

Damping off, caused mainly by Pythium, Rhizoctonia and Phytophthora fungi, is the most serious nursery disease of tomato, chilli, brinjal and capsicum and can destroy large numbers of seedlings in a few days. It can kill 30 to 80 percent of seedlings in a badly managed nursery, leaving farmers short of healthy transplants. Because it spreads fast in wet crowded conditions, a single mistake in nursery management can wipe out the seedbed and delay the whole crop.

Organic & cultural control

Prepare raised nursery beds with very good drainage and never overwater. Treat seed with Trichoderma viride or Trichoderma harzianum before sowing, which is highly effective and safe. Solarise the nursery soil by covering moist beds with clear plastic for a few weeks in summer to kill the fungi. Sow seed thinly to avoid crowding, mix well rotted compost enriched with Trichoderma into the bed, and water in the morning so the surface dries by evening. Remove affected seedlings promptly.

Chemical control

Treat seed before sowing with a fungicide such as thiram, captan or carbendazim plus mancozeb at the recommended rate. If damping off starts in the nursery, drench the beds with a copper oxychloride solution or carbendazim, or use metalaxyl plus mancozeb where Pythium is the cause, and reduce watering at once. Avoid overdosing as it can harm seedlings. Always follow the product label dose and consult your KVK or agronomist for the correct seed treatment and drench.

Always follow the product label, the recommended pre-harvest interval, and your local KVK or agronomist. Pesticide approvals change, so verify before use.

Prevention

Always use raised beds with good drainage, sow seed thinly and avoid overwatering, which is the single biggest cause. Treat all seed with Trichoderma or a fungicide before sowing and use clean, solarised or fresh soil for the nursery. Do not use heavy, water holding or previously infected soil. Give the nursery good sunlight and air movement, water only in the morning, and avoid excess nitrogen that makes seedlings soft. Raising seedlings in pro trays with sterile media greatly reduces the risk.