Causes, harmful symptoms and integrated control methods of watermelon Fusarium wilt
Watermelon Fusarium wilt is commonly known as “vine death disease”, and it can occur at all stages, with the heaviest incidence during the fruiting stage, and it is more severe when soil water content is high and humidity is great, so what are the causes of watermelon Fusarium wilt? What are the harmful symptoms? Detailed integrated control methods attached!
1. Causes
Watermelon Fusarium wilt is caused by infection by a fungus of the subdivision Deuteromycotina, Fusarium oxysporum f. sp. niveum, the pathogen overwinters in soil and in unrotted infected fertilizer, and in the absence of a host it can survive for 5-6 years, with some pathogens surviving more than 10 years, the pathogen mainly invades through root wounds or the intercellular spaces at the tips of root hairs, first growing between and within the host vessel cells, then entering the vascular bundles and developing in the ducts, the pathogen secretes pectinase and cellulase, decomposing and destroying cells, causing pectin-type substances to accumulate in the ducts, blocking the ducts and affecting water transport, causing the plant to wilt, it spreads through infected soil, and with continuous cropping there are many pathogens in the soil, and the diseased plant rate can reach about 70%, diseased residues and diseased manure, as well as seeds, can also transmit the disease.
2. Harmful symptoms
When seedlings are affected they show damping-off, and after watermelon seedlings are transplanted, the lower leaves wilt, then all the leaves of the whole plant wither and die, the stem base constricts and brown lesions appear, sometimes an amber-colored gelatinous substance flows from the diseased part, on which white mold and pale red sticky matter (conidia) grow, the vascular bundles of the stem turn brown, sometimes longitudinal cracks appear, and the roots turn brown and rot together with the stem.
3. Integrated control
The most effective method for controlling watermelon Fusarium wilt is grafting to replace the roots, using cucurbit crops with high resistance to Fusarium wilt such as bottle gourd or Xintuzuo as rootstock to graft watermelon varieties; as long as care is taken to completely sever the watermelon roots and ensure that the graft union does not come into contact with the soil when the seedlings are planted, the occurrence of watermelon Fusarium wilt will be effectively prevented.
Planting disease-resistant watermelon varieties is the first-choice measure, such as selecting varieties like Xinong No. 8 and Fengkang No. 8; watermelon Fusarium wilt pathogens find it difficult to infect bottle gourd, edible gourd, pumpkin and others, and grafting onto these crops to replace the roots is a better way to solve watermelon Fusarium wilt; watermelon Fusarium wilt can survive in soil for 10 years, but in water it survives for only more than 130 days, so paddy-upland rotation is the best method to prevent Fusarium wilt; before sowing, soak seeds in a 2-4% bleaching powder solution for 30 minutes, then remove them and wash them clean, which can kill Fusarium wilt pathogens and anthracnose pathogens on the seed surface; for the nutrient soil used for raising seedlings, pond soil, paddy field soil or wall soil should be selected, and soil from melon fields or vegetable gardens must not be used, farmyard manure must be fully rotted, and farmyard manure containing diseased plant residues must not be used.
The above is the introduction by Tuliu.com to the causes and control methods of watermelon Fusarium wilt; for own-rooted watermelon seedlings that have not been grafted, the plant protection policy of “prevention first, integrated control” should be adhered to, and integrated control measures such as agricultural control and biological control should be earnestly implemented.