Pineapple wilt disease causes leaf wilt and root rot and death; how to prevent and control it

    Pineapple wilt disease, also known as root rot, is called "pineapple plague" locally. This disease occurs in Hainan, Guangdong, Guangxi, Fujian, Taiwan, China and other places. 

Pineapple wilt disease

    1. Symptoms: In the early stage of the disease in infected pineapple, the lower leaves above ground turn yellow and red, shrink, lose their luster, and the leaf margins curl inward; later the leaf tips dry up, the leaves wilt, and the plant stops growing. As the disease progresses, rot spreads from the root tips until part or all of the root system rots, and the plant dies. Most people believe that pineapple wilt disease is caused by infection with a virus transmitted by the pineapple mealybug. 

    2. Conditions for onset: ① Climatic factors. Generally, the disease occurs easily in the hot, dry autumn and winter, but it also occurs in the low-temperature, rainy spring. In Hainan Province, pineapple wilt disease mostly occurs from November to January-February of the following year. ② Plant growth factors. Generally, plots where pineapple plants grow vigorously, with high fertilizer and water levels and high density, are prone to the disease and suffer more severely. ③ Environmental condition factors. In mid-slope depressions, where water accumulates easily, on steep slopes, where soil erosion is severe, where roots are exposed, and where water retention is poor, roots are prone to dying and wilting. ④ Underground pest factors. Pests such as white grubs, termites, and earthworms that feed on the underground roots of pineapple can aggravate wilt disease. 

    3. Prevention and control techniques: ① Strictly select strong, disease-free pineapple seedlings. Do not save seed or introduce seedlings from diseased areas or diseased fields. If seedlings are introduced from diseased areas, the base of the seedling rhizome must be soaked in the pesticide solution for 2 minutes, and placed upside down on its side so that the pesticide solution accumulates at the leaf bases, in order to kill the mealybugs remaining in the pineapple seedlings; after drying, plant them. For soaking seedlings, use 50% malathion emulsifiable concentrate at 800 times dilution, 40% dimethoate at 800-1000 times dilution, or 80% dichlorvos emulsifiable concentrate at 1000 times dilution.

    ② Pesticide and fertilizer treatment. When diseased plants are found, the above pesticides can be mixed with 50% thiophanate-methyl wettable powder at 400 times dilution and 1-2% urea and sprayed to promote yellow leaves turning green. The soil surface around diseased pineapple plants and at the base of other healthy plants must be drenched with any one of the above insecticides to kill mealybugs and underground pests.

    ③ Improve the plantation environment. Choose suitable planting sites. Strengthen management. Use high-ridge planting to avoid water accumulation and soil erosion in the pineapple plantation. For kaolin and heavy clay soils, increase the application of organic fertilizer, improve soil aeration, and promote root growth. Promptly dig out and burn diseased pineapple plants.