Vicia faba root rot and stem rot
Symptoms Vicia faba root rot: Vicia faba roots and stems are infected, pathogenic parts turn black and rot, most of the lateral roots or major roots shrink, and the lower leaves of the aboveground plants produce black and white patches of varying size, causing the entire leaf to change. Black withers, dead spots appear between the upper veins, and severe leaf and stem darkening shrinkage and death. Basal rot: The root is black and rots first, then spreads to the base of the stem, and the diseased department rots and dies without wilting, which is different from root rot.
The pathogen of pathogenic faba bean root rot was Fusariumsolani f.sp.fabaeYu et CTFeng, and the faba bean faba bean specialization type was a semi-known fungus subphylum fungi. Large conidia are slightly curved, spindle-shaped, with 0-6 membranes, typically 3, size 34.85, 2 (um). Small conidia are born on the stems of the conidial spores with irregular stems. Conidia oblong to ovoid or short rod, unit cell, size 6.62.1 (um). The chlamydospores are terminal or metastable, mostly single-celled, spherical or elliptical, with a size of 10,610 (um). Individuals have 1-2 diaphragms, solitary, sometimes joined into short rods, with a smooth surface. The sexual state is Nectria sanguinea (Bolt.) Fr., which is called Ascomycota spp.
There are mainly two kinds of broad bean stalk rot pathogens: Fusarium averenaceum (Corda ex Fr.) Sacc.f.fabarum Ruan et a1. Called O. granulosus aerial mycelia and F. avenaceum f.fabalis Ruan et al. Spore-myxoplasmic type, can infect broad beans caused by base rot and root rot. All belong to semi-informer Inglea fungi. The morphology of the two bacteria is similar. The hyphae are white with magenta and cotton wool. The large conidiospores are bent and worm-shaped and filamentous. The apical cells are narrow, slightly pointed, and have large curvature. They have 0-12 septa, 5 Most of them are small; small conidial spores are rare or absent, with 0-1 septa; venous nucleus is dark blue, 0.2-2.5 mm in diameter, and does not produce chlamydospore.
In Yunnan, Yunnan Academy of Agricultural Sciences investigated the flora of pathogens of faba bean root and stem disease with Fusarium spp., and Rhizoctonia solani was rare. The dominant species of Fusarium is Fusarium oxysporum, followed by Fusarium oats. Among them, Fusarium solani, Fusarium verticillioides, and Rhizoctonia solani caused root rot. Fusarium oxysporum, Fusarium oats, Fusarium falciparum, Fusarium arborescens, Fructus lyrata, and Yin cause root rot.
Transmission Pathways and Pathogenic Conditions Germs can survive or spread on seeds. Seed carrier rates range from 1.2% to 14.2%, and are mainly transmitted through the seed coat on the seed surface. In addition, mycelium and chlamydospore are associated with the diseased body in the soil. The winter overwintering bacteria can become the primary source of infection for the following year. The incidence of the disease is related to soil moisture content. When the groundwater level is high or the water in the field is high, the field water holding capacity is higher than 92%, and the high-lying plots have a lighter incidence. The fields with intensive farming and broad bean, wheat, and rapeseed rotations are lighter in the winter. The differences between the years are related to the meteorological conditions. In the year of raining and sowing, the roots were severely damaged.
Control methods (1) Rotation of broad bean root rot and stem rot pathogens are narrow in the host range, and the rotation of broad beans, wheat, rape, etc. for more than 3 years is effective. However, it should not be rotated with legumes. (2) Strengthen field planning and management Select a good block of Gaoshao drainage, apply adequately decomposed organic fertilizer, and do not use the diseased plants to produce fertilizer, and timely clean the pastoral after harvest. Do not lose fertilizer or water in the growth process of broad bean and strengthen irrigation and drainage. To prevent the soil from getting too dry and too wet. (3) Seed treatment soaked with warm water at 56°C for 5 minutes or soaked with 50% carbendazim WP 700 times for 10 minutes before sowing. (4) Chemical control: Mix 50% carbendazim WP with 50 parts of fine dry soil, remove 66.7m2 of 1.5kg at the base of seedlings, or spray 50% of the seedling stem base at the early stage of disease. Wet powder 600 times liquid, 70 thiophanate-methyl wettable powder 500 times liquid, every 7-10 days, continuous control 2-3 times, there is a certain control effect.
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