How to prevent and control damping-off of codonopsis (Codonopsis pilosula) seedlings?

The disease mostly affects the base of the stem below the epidermis, at the boundary between dry and moist soil. It begins as yellow-brown sunken lesions; as the lesions enlarge they girdle the stem and gradually penetrate into the stem, causing rot and death. Once infection occurs it spreads rapidly, killing plants in patches.

Control methods:

Choose well-drained sandy soil with good ventilation, and increase phosphorus and potassium fertilizer.

Treat seeds with 50% carbendazim wettable powder or 65% zineb wettable powder at 0.2%-0.3% of the seed quantity; alternatively, mix 50% carbendazim wettable powder or 65% zineb wettable powder with soil at 7-8 grams per sq m, spread it on the raised beds and ridges, and rake it in deeply.

Spray treatment when the disease occurs:

① 3.2% metalaxyl-hymexazol aqueous solution, after emergence, at 10 grams per sq m diluted in 3 kg of water.

② 3% guangkuling aqueous solution at 700-800 times dilution, poured or sprayed at the stem base, gives very good results.

③ 70% dexon wettable powder at 1000-1500 times dilution, or 50% carbendazim wettable powder at 800 times dilution, applied as a drench at 4-8 kg per sq m, also gives very good results.