Occurrence and Control Methods of Root Rot and Soft Rot in Patchouli

1. Symptoms and Causes

PatchouliRoot rot occurs at the roots, with the junction between the underground stem and the root being more prone to rotting, which then gradually spreads to the aboveground parts of the plant. This causes the cortex to turn brown and rot with an alcoholic smell, often exuding a brown gummy substance, and the branches and leaves wilt and die. Root rot mainly occurs under conditions of intense midsummer heat (above 28°C), frequent rain, heavy clay soil, or large fluctuations in dryness and humidity, poor drainage, too-deep planting, root injury, as well as insufficient water and fertilizer and weakened plants.

2. Control Methods

(1) When the disease occurs locally, diseased plants should be dug out and burned promptly, and lime should be spread in the soil at the site of the diseased plants for disinfection. Other nearby plants can be sprayed with a 500-1000 times dilution of 25% carbendazim wettable powder, sprayed 2-3 times consecutively at intervals of 3-5 days, or sprayed with a 500-600 times dilution of 75% chlorothalonil wettable powder, 3-4 times consecutively at intervals of 2-3 days. This is to prevent the pathogen from spreading and expanding, and healthy branches should be pressed and buried into the soil to let them develop new roots. If the area affected by root rot and soft rot is relatively large, chlorothalonil can be used to irrigate the diseased plants for control. The concentration should follow the instructions and be determined according to the severity of the disease.

(2) Biological pesticide control also has a good effect. At present, the Haopu brand high-efficiency biological immune fungicide produced in Dalian is mostly used, with a common dosage of 20-50 milliliters per mu diluted to an 800-1500 times solution. Apply by spraying, 3 times consecutively, with an interval of 7 days.

(3) In hot summer weather, other crops should be planted for shade, or grass should be used as mulch for shade.

(4) During the rainy season, accumulated water should be drained promptly to avoid excessive soil moisture.

(5) Disinfect the soil before planting; at planting time, soak the roots for 10 minutes in a 100 times dilution of 65% zineb wettable powder, or a 1000 times dilution of 50% carbendazim, or a 1:1:100 Bordeaux mixture.

(6) Before the disease occurs, irrigate each square meter with 10 kg of a 200 times dilution of 50% carbendazim. During the disease period, irrigate the diseased plants with a 1000-2000 times dilution of 50% thiophanate-methyl, or a 500-1000 times dilution of 50% carbendazim.

(7) Continuous cropping is not suitable, otherwise it will cause diseases in patchouli plants.