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What are the control methods for soybean downy mildew?
Soybean downy mildew damages seedlings, leaves and seeds. After the first true leaf unfolds, chlorotic patches appear along both sides of the veins. On the leaves of mature plants, round or irregular yellow-green specks with indistinct edges appear on the surface, later turning brown, and a grayish-white mold layer forms on the underside of the leaves. The surface of diseased seeds is covered with a grayish-white layer of mycelium containing large numbers of the pathogen's oospores. The pathogen overwinters as oospores on seeds and in diseased leaves, becoming the primary infection source for the following year. The disease begins to appear in mid-to-late June each year, with the peak period from July to August, and in rainy years it often becomes severe. Control
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How to Identify Soybean Downy Mildew? A Complete Guide to Prevention and Control Techniques
Downy mildew is found in all major soybean-producing regions of China, occurring more frequently in the cold-climate areas of the Northeast and North China during the soybean growing season, with the disease worsening in rainy years, severely causing premature leaf drop or wilting, seed rot, and yield losses of 30%-50%. It mainly damages the leaves, pods, and seeds of seedlings or mature plants. Symptoms: The pathogen on infected seeds causes systemic infection leading to seedling disease, but the cotyledons show no symptoms. After the first pair of true leaves unfolds, chlorotic patches appear along both sides of the leaf veins, spreading along the main vein and lateral veins, causing the entire leaf to lose chlorophyll, with
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High-yield Cultivation Techniques for Soybean with Wide Ridge and Narrow Row Close Planting
Wide ridge and narrow row close planting of soybean can increase the canopy leaf area index, make full use of light energy, and achieve the goal of increasing yield. (1) Site selection and land preparation. The best preceding crops are wheat, corn or potato. Ridging is done as sowing proceeds. The ridge spacing is 130 cm, the ridge height is 25 cm, and the ridge top width is 3O cm. (2) Variety selection. For wide ridge and narrow row close planting of soybean, the varieties selected should generally be 168, ZOQI, 9409B, Fengshou 544, Mijiawang, Hefeng 25, Hebing 93-BS, etc. Seed selection should be carried out before sowing.
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Introduction to the Root Characteristics and Structure of Soybean
The root system of soybean is a taproot system. It is divided into a main root and lateral roots, and both the main root and the lateral roots are densely covered with root hairs. The main part of the root lies 5-20 cm deep in the soil, and the whole root system is roughly bell-shaped. On soybean roots, rhizobia live in symbiosis with the soybean. When the soybean germinates, the rhizobia invade the root, and when the soybean grows its first compound leaf, root nodules have formed on the soybean roots, first on the main root and then gradually spreading to the lateral roots. The root nodules are produced through the action of rod-shaped rhizobia that have 1-2 flagella at one end. They are aerobic bacteria, mainly growing on the root system near the soil surface
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How should soybeans be harvested properly? A full breakdown of the key methods
Soybeans should be harvested promptly once mature. If harvesting is too late, the pods lose too much moisture and are prone to shattering and dropping seeds, causing losses. The suitable harvest period should be determined according to different harvest methods. When harvesting with a sickle, begin harvesting after all soybean leaves have fallen, as nutrient transport to the seeds has essentially stopped by then. Mechanical harvesting must be done after the whole plant is fully mature and dry. Manual harvesting is best done in the morning, when the soybean plants have a higher moisture content, so they do not prick the hands and are less prone to pod shattering. A low stubble height is required, with no "horse ears" left exposed and no missed cutting.
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Causes of Soybean Sclerotinia Stem Rot and Its Control Measures
1. Symptoms The first thing to catch the eye in the field is the upper leaves of the plants turning brown and dying. Brown lesions continue to develop on the stems of diseased plants, producing white cottony mycelium and white granular material, which later turns black and becomes sclerotia. When the stem of a diseased plant is cut lengthwise, black cylindrical sclerotia are seen arranged in rows inside. After the diseased plant dies, it turns grayish white, the hollow stem cortex often rots into a hemp-fiber-like state, and the sclerotia on the outside of the diseased plant readily fall off. The lesions on the pods are brown, and the pods die rapidly without setting seed, finally turning pale white; lightly affected pods may still set seeds, but the affected seeds are rotted or
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Soybean Good Seed Propagation Methods and Key Technical Points
Soybean is a self-pollinating crop. Due to mechanical mixing, adverse climatic and cultivation conditions, and natural cross-pollination, the varietal characteristics often deteriorate. Therefore, self-pollinated seeds cannot be used long-term, and seeds should be replaced every three years. Thus, it is necessary to persist in purification and rejuvenation and carry out good propagation work to maintain the varietal characteristics of good varieties. 1. Purification and rejuvenation methods for soybean varieties (1) Line selection The commonly used method for soybean purification and rejuvenation consists of three steps: individual plant selection, line identification, and mixed high-ratio propagation. Three plots are established: an individual plant selection nursery,
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Detailed Explanation of Key Soybean Field Management Techniques
1. Thin seedlings early. As the farming proverb says: "Thin seedlings an inch early, and it is as good as a load of manure." Thinning is especially important for mechanically drilled soybeans or hand-sown beans planted with a large plow in furrows. After thinning, the seedlings are distributed evenly and reasonably, which promptly prevents seedlings from crowding one another, reduces consumption of soil nutrients and water, and allows the seedlings to develop evenly and vigorously, thereby increasing soybean yield. Thinning is generally carried out during the soybean seedling stage, when the two opposite single leaves are flat and spreading and compound leaves have appeared. During thinning, diseased seedlings, weak seedlings, and mixed seedlings must be pulled out. 2. Cultivation and weeding. Generally, three hoeings and three hillings are required. Specific timing:
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New soybean variety Tiedou 41 approved
The new soybean variety "Tiedou 41", bred by the Tieling City Soybean Science Research Institute in Liaoning Province (postal code: 112616, tel: 0410-2601837), recently passed variety approval in Liaoning Province. This variety has a growth period of about 126 days and belongs to the medium-maturity group, with determinate pod-setting habit, oval seeds, yellow seed coat, glossy, yellow hilum, and 100-seed weight of 20.9 grams. The crude protein content of the seeds is 43.94%, and the crude fat content is 20.72%. It is resistant to soybean mosaic virus disease. The average yield per mu reaches
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Introduction of new soybean varieties for farmers' reference in seed selection
Xinfeng No. 1 was developed by the Agricultural Technology Extension Station of Hongmiaozi Township, Xinbin County, through sexual hybridization and selection using Chang No. 4 as the female parent and Qunxuan No. 1 as the male parent. It was approved by the Crop Variety Approval Committee of Liaoning Province in December 2002. The variety has a growth period of 121 days and belongs to the early-maturing group. The average plant height is 94.7 cm, with a semi-determinate podding habit and 17.9 nodes on the main stem. The stems are thick and tough, the root system is well developed, and it is lodging-resistant. The leaves are round, the pubescence is gray, and the flowers are white. The pods are grayish-brown, with 59.9 pods per plant, and many pods contain 3-4 seeds. The seeds are yellow with a yellow hilum,
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