Integrated Control Methods and Technical Key Points for Soft Rot in Zhacai (Pickled Mustard Tuber)
Zhacai (pickled mustard tuber), a family of the phylum Angiospermae, class Dicotyledoneae. Mostly herbaceous plants. Zhacai is a type of mustard, generally referring to the leafy mustard group, such as jiutoujie, xuelihong, zhuxuejie, doufupijie, etc. Zhacai is a semi-dry, non-fermented pickled vegetable, made by pickling stem mustard as the raw material. It is one of China's famous specialty products and, together with French pickled cucumber and German sweet-and-sour cabbage, is known as one of the world's three great pickled vegetables. It first appeared in 1898 in Fuling, Sichuan, China, and was then called “Fuling Zhacai”. Because the processing requires pressing out the water from the vegetable, it is called “zhacai”. It has now spread to more than 30 cities and counties within Sichuan Province, and is also produced in Zhejiang, Fujian, Jiangsu, Shanghai, Hunan, Guangxi, Taiwan and other provinces (municipalities directly under the Central Government, autonomous regions).
Zhacai (Brassica juncea var. tumida) is a plant of the family Brassicaceae, often covered with simple hairs, branched hairs, stellate hairs or glandular hairs. Flowers are bisexual, usually in racemes; sepals 4, free, in two whorls; petals 4, clawed, arranged in a cruciform corolla, a few without petals (such as shepherd's purse and wuban han cai); stamens 6, in two whorls, the outer whorl of 2 shorter, the inner whorl of 4 longer, called tetradynamous stamens; carpels 2, connate, ovary 1-loculed, with parietal placentation, divided into 2 locules by a false septum in the center, each locule usually with many ovules. The fruit is a silique; those nearly equal in length and width are called silicles, and those several times longer than wide are called siliquae, such as shepherd's purse and pepperwort, which are silicles, and Chinese cabbage and radish, which are siliquae. This family has about 350 genera and 3000 species of plants, widely distributed throughout the world. China has 90 genera and 300 species, most numerous in the north and northwest.
In mature stem tumor mustard before bolting, the aboveground part is 60-80 cm tall, the main root of the underground part is 20-30 cm long, and the whole plant generally weighs 2-4 kg. The lower part of the aboveground portion is the enlarged tumorous stem, on which grow more than ten large leaves; at the base of the petioles of the large leaves grow tumorous fleshy stems, generally with 3-5 obvious tumorous protrusions. The epidermis of the tumorous stem is green and smooth, and the flesh beneath is white and thick, tender and crisp in texture. The tumorous stem portion, namely the green vegetable head, generally weighs about 0.5 kg each, with larger ones 1-1.5 kg. Cooked green vegetable heads mixed with seasonings are very tasty; after cooking, the broth has a chicken-soup-like savory flavor. Pickles made from green vegetable heads appear tender, crisp and distinctive.
Integrated control of soft rot in zhacai
Soft rot is an important disease of zhacai and can cause large-scale death in vegetable fields. Its symptoms are yellowing, wilting leaves, rotting stems, grayish-white seed pods, and lodging of the plants. The integrated control techniques below, studied by our institute for many years, have achieved very good results.
1. Strengthen cultivation management
Implementing crop rotation in seed-production vegetable fields can reduce the severity of the disease. It is best to rotate with gramineous crops such as rice and wheat, and after harvest, plow the soil deeply to bury the pathogens deep in the soil. Field operations should avoid causing wounds to the plants, and high-ridge cultivation should be adopted, with good drainage and prevention of flooding irrigation. Use nitrogen fertilizer correctly, appropriately increase phosphorus and potassium fertilizer, and do not apply undecomposed fertilizer. Early diseased plants can be pulled out and buried deep, and healthy plants should be selected for seed production. Before sowing, soak the seeds in 10% salt water, then wash them clean with fresh water.
2. Thoroughly control insects to prevent disease
Insect pests and diseases are closely related, so in the early stage, attention should be paid to controlling underground pests. At the seedling stage, control of flea beetles, cabbage caterpillars and daikon leaf beetles should be combined with aphid control. For cabbage caterpillars before the third instar, biological control can be used first, such as Bacillus thuringiensis preparations, cabbage caterpillar granulosis virus preparations, etc., as well as “fourth-generation” chemical pesticides? urea-based preparations that inhibit insect chitin synthase (diflubenzuron 1, diflubenzuron 3, etc.), which can both control pests and avoid environmental pollution. “Malathion” at 500-1000 times dilution can also be selected to control aphids, flea beetles and spider mites at the same time. For pests occurring later, 2.5% deltamethrin emulsifiable concentrate at 6000-8000 times dilution, or 2.5% cyhalothrin emulsifiable concentrate at 6000-8000 times dilution, etc., can be used for control.
3. Chemical control
In the early stage of bacterial soft rot, 100-150 mg/kg streptomycin sulfate or agricultural streptomycin can be sprayed, once every 7 to 10 days, for 2-3 consecutive times, or 70% fenaminosulf wettable powder at 800 times dilution can be used for spraying. For sclerotial soft rot, 50% procymidone wettable powder at 2000 times dilution, or 50% thiophanate wettable powder at 500 times dilution, or 50% carbendazim wettable powder at 600-800 times dilution, or 40% dimetachlone wettable powder at 1000-1500 times dilution can be selected, spraying 60 kg of pesticide solution per mu, once every 10 days, for 2-3 consecutive times.