Identification and Control of Lotus Root Rot
Lotus root is the rhizome of the lotus, a plant in the water lily family. It is plump and jointed, with small tubular holes inside, and when broken, threads connect the pieces. The rhizome is slightly sweet and crisp, and can be eaten raw or cooked, and its medicinal value is quite high. Its roots, leaves, flower stamens and fruits are all treasures that can nourish the body and be used as medicine. Made into powder, lotus root can aid digestion and stop diarrhea, stimulate the appetite and clear heat, nourish and strengthen the constitution, and prevent internal bleeding. It is an excellent liquid food and nourishing delicacy for women, children, the elderly, and those who are frail and often ill. During the reign of Emperor Xianfeng of the Qing Dynasty, it was designated as a tribute food for the imperial kitchen. Lotus root originated in India and was later introduced to China.
The underground stem of the lotus is called lotus root. It is a plant of the water lily family and an aquatic vegetable. It is plump and jointed, with tubular holes inside, and is divided into red-flower lotus root, white-flower lotus root, and twisted lotus root. Red-flower lotus root is slender, with a brownish-yellow, rough outer skin, low moisture, and is not crisp or tender; white-flower lotus root is plump, with a delicate, smooth outer surface, silvery white in color, crisp, tender and juicy, with a rich sweet taste; twisted lotus root is pink, with a rough outer surface and high starch content.
Lotus root has a high vitamin C content (40 to 50 mg per 100 grams) and also contains polyphenolic compounds and peroxidase, which can thoroughly clean out the “garbage” in the human body. Lotus root contains relatively rich high-quality protein (about 2%), and its amino acid composition is close to human needs, with high biological value. In addition, lotus root is also rich in dietary fiber (about 2%), and its calcium and phosphorus contents are also relatively high (calcium 89 mg, phosphorus 285 mg).
Lotus root has a relatively high iron content, and eating it regularly can prevent iron deficiency anemia. Rich in vitamin C and dietary fiber, it is quite beneficial for weak conditions such as liver disease, constipation, and diabetes. The tannic acid it contains has the effect of constricting blood vessels and stopping bleeding, making it extremely suitable for people with blood stasis, vomiting blood, nosebleeds, blood in the urine, blood in the stool, as well as postpartum women and people with hemophilia. It can relieve summer heat and clear heat, and is a good food for dispelling summer heat.
Understanding and Control of Lotus Root Rot
Lotus root rot, also known as fusarium wilt and decay disease, is one of the most common and serious diseases in lotus root growing areas. The disease mainly damages the underground stem and roots, and causes yellowing of the aboveground leaves, with severe cases withering. Under conditions of high temperature of 23 to 30 degrees C and continuous rainy weather, the disease is severe. In the early stage of the disease, there are no obvious symptoms. In the later stage, the affected parts of the diseased stem, lotus whip and roots show brown to purple lesions, the diseased stem shrinks longitudinally, the vascular tissue of the lotus whip also turns brown, and the lotus roots necrose. The leaves emerging from diseased lotus roots turn pale, with green wilting appearing first at the leaf margins, then expanding inward, and finally the entire leaf curls and scorches. In severely affected fields, the whole field turns withered and yellow, as if burned by fire. When the lotus roots are dug out, a pink sticky substance (the fungal conidia mass) can be seen at the nodes.
Control methods for lotus root rot:
1. Select superior varieties. Use disease-free seed lotus roots, rotate crops every 2 to 3 years, and before transplanting, apply 100 kg of lime per mu for soil treatment.
2. Seedling treatment. Spray the lotus roots with a 800-fold dilution of 50% carbendazim or thiophanate-methyl wettable powder, and seal with plastic film for 24 hours to fumigate the seeds.
3. Strengthen field management. Apply decomposed organic fertilizer, increase phosphorus and potassium fertilizer, manage water according to the water requirement at each growth stage, and promptly remove diseased plants in the early stage of the disease.
4. Stem and leaf treatment. Spray with 12% copper green 700-fold, or carbendazim 600-fold, or thiophanate-methyl 700-fold. At the same time, 50% carbendazim plus 75% chlorothalonil wettable powder can be used, mixed with 30 kg of fine soil per 500 grams per mu, piled and fumigated for 3 to 4 hours, then applied to the field while maintaining a shallow water layer. The two methods can be carried out at the same time, once every 7 days, for 2 to 3 treatments.