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What are the key points for controlling stem blight in carnations?

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Identification points: Carnation stem blight attacks the roots, the stem at the soil line, and the leaf sheaths of the plant. The affected parts turn brown, and the leaves yellow and wither from the bottom upward; the stem at the soil line dries up, and the pith of the stem turns brown and rots. Occurrence characteristics: The pathogen is a fungus. The fungus overwinters in the soil as chlamydospores or as mycelium in diseased plant debris
Identification points: Carnation stem blight attacks the roots, the stem at the soil line, and the leaf sheaths of the plant. The affected parts turn brown, and the leaves yellow and wither from the bottom upward; the stem at the soil line dries up, and the pith of the stem turns brown and rots.

Occurrence characteristics: The pathogen is a fungus. The fungus overwinters in the soil as chlamydospores or as mycelium in diseased plant debris, and the following year it infects the roots and stem base of the plant, forming brown lesions that gradually enlarge and spread into the pith, causing the plant to slowly die as the transport of nutrients and water is blocked. The disease is more obvious on sunny days following continuous rainy weather.Control methods:(1) Use well-rotted compost and avoid excessive application of nitrogen fertilizer; control the amount of watering after the seedlings have established.(2) Mix 75% quintozene wettable powder with soil at a 1:40 ratio and apply it around the roots.(3) Before the disease occurs, spray with a 800-1000 times dilution of 40% iminoctadine tris(albesilate) wettable powder, once every 7 days, for 4 consecutive sprays; in the early stage of the disease, spray with a 500-1500 times dilution of 50% carbendazim wettable powder, a 800-1000 times dilution of 80% thiram wettable powder, or a 2000-3000 times dilution of 12.5% diniconazole wettable powder.

Control techniques for carnation stem blight

Identification points: Carnationstem blight attacks the roots, the stem at the soil line, and the leaf sheaths of the plant. The affected parts turn brown, and the leaves yellow and wither from the bottom upward; the stem at the soil line dries up, and the pith of the stem turns brown and rots.

Occurrence characteristics:The pathogen is a fungus. The fungus overwinters in the soil as chlamydospores or as mycelium in diseased plant debris, and the following year it infects the roots and stem base of the plant, forming brown lesions that gradually enlarge and spread into the pith, causing the plant to slowly die as the transport of nutrients and water is blocked. The disease is more obvious on sunny days following continuous rainy weather.

Control methods:

(1) Use well-rotted compost and avoid excessive application of nitrogen fertilizer; control the amount of watering after the seedlings have established.

(2) Mix 75% quintozene wettable powder with soil at a 1:40 ratio and apply it around the roots.

(3) Before the disease occurs, spray with a 800-1000 times dilution of 40% iminoctadine tris(albesilate) wettable powder, once every 7 days, for 4 consecutive sprays; in the early stage of the disease, use 50%carbendazimwettable powder at a 500-1500 times dilution, 80% thiram wettable powder at a 800-1000 times dilution, or 12.5% diniconazole wettable powder at a 2000-3000 times dilution for spraying.

Control methods for carnation damping-off

Identification points

Carnation damping-off occurs at the seedling stage, producing oval dark brown lesions on the stem that are sunken; as the disease develops the lesions enlarge and can encircle the young stem, the affected part constricts, and the stems and leaves above the lesion wither and die; in the middle and later stages, brown concentric ring spots appear on the stems of diseased plants, later turning dead white, and the leaves yellow and wither. When humidity is high, mycelium grows on the lesions; the mycelium is cobweb-like and brown, and sometimes brown irregular sclerotia can be seen. When seed propagation is infected, it can cause seed rot and failure of emergence.

Occurrence characteristics

A fungal disease of the seedling stage. The pathogen is Rhizoctonia. Under suitable temperature and humidity conditions the mycelium invades the host and spreads with rainwater, irrigation water, and farming operations. It occurs frequently when seedlings are too dense, leggy, or when humidity management of the seedbed is improper.

Control methods

(1) Choose a disease-free seedbed with good drainage, and thoroughly disinfect the bed soil. For pot soil for home flower growing, high-temperature sterilization can be used; for field and greenhouse cultivation, formaldehyde fumigation can be used: 20 days before sowing, spray 40 ml of formaldehyde mixed with 2-4 liters of water per sq m, and immediately seal it with plastic film for one week.

(2) In the early stage of the disease, choose 75% chlorothalonil wettable powder at a 800 times dilution, 50% carbendazim wettable powder at a 800 times dilution, or 20% flutolanil wettable powder at a 2000 times dilution for spraying.

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