Symptoms can be from the seedling stage to the adult stage, with more infections at the flowering stage, mainly affecting the roots or rhizomes. The lower leaves of the diseased plants begin to yellow and gradually develop to the middle and upper parts, causing the whole plant to turn yellow and wither. The main and lateral roots become black, vertical roots, vascular bundles become brown or soil red, root nodule and root hair is significantly reduced, from the light, the plants are dwarfed, stems are thin, leaves are small or light green leaves, individual branches are wilting or Wilt-like, mildly diseased plants are still flowering and scabbing, but the number of pods is greatly reduced or the grains are thin; the stem base of the severely diseased plant is contracted or the depression is browned, showing a "slim waist" shape, and the cortex of the diseased part rots or a large number of dead plants after flowering. No crops were received, causing all fields to turn yellow. This disease has been a major disease that has commonly occurred in pea cultivation areas at home and abroad.
The pathogen Aphanomyces euteiches Drechsler called root rot fungi, Pythium ultimum Trow called the ultimate Pythium, all belong to the flagellin subphylum fungi. Fusarium solani (Martius) f.sp.pisi (Jones) Snyderet Hansen said that the eggplant type Fusarium spp. A.euteiches ovipositor subglobose or subglobose, endogenous on the usually more branched, size 19-24um, the inner surface of the wall is corrugated. Oval spores are oval or subglobose, nearly colorless to deep yellow, 14-31um in diameter, and l-2um in wall thickness. Male tops, often curved branches. The mycelium branches are not very luxuriant, and the zoosporangium is directly formed by the pellicles of the vegetative mycelium. After maturity, tens to hundreds of zoospores are released. The zoospores first stop in clusters, and when they rest, they have a spherical shape. 6-10um, soon dispersed, Mr. Dodge a nipple, released from the nipple at the end of a number of long flagellar zoospore, sometimes zoospores can germinate after germination, grow bud tube. P.ultimum colonies on the CMA no special shape, radial on the PCA, the main hyphae width 6.2um, spherical or nearly spherical sporangia, multiple births, individual primary size 19-24um; ovipositor spherical, smooth, More than one student, individual students, size 20 to 23um; male 1-3, mostly one, cystic curved, typical of the same raw, sessile, close to the ovipositor, a small number of different wire, with Shank, size 9.2-12.35.5-7.6 (μm); oospore spherical, size 16-19um, containing one storage ball and one refractive body. Yin silk growth temperature 32 °C, the highest 36-40 °C, the lowest 4 °C. F.solani colonies on PDA medium were round or nearly round, white, and cotton-like, and there were a few ovoid or oblong small conidia after microscopic examination. Large conidiospores can be formed in the oat husk culture medium, showing a guillotine shape with blunt and curved ends. With more than three diaphragms, the foot spores are not obvious. The chlamydospores are terminal, internode, or connate, pale brown, round or nearly round, and have a smooth surface.
Thielaviopsisbasicola (Berk. et Br.) Ferr., called Fusarium oxysporum (Schl.), Fusarium oxysporum (Schl.), Rhizoctonia solani kuhn, Rhizoctonia solani, Sclerotinia sclerotiorum (Libert) de Bary, Sclerotinia sclerotiorum, Root rot can also be caused.
Transmission routes and onset conditions Both root rot fungus and ultimate pythium can both live in the soil and live in the soil with ovipositors and mycelium. Sputum sac is produced when there is sufficient water in the spring of the following spring. The sporocysts release a large number of zoospore, which invade through the lower axis of the seedling cotyledon or the outer cortex of the root after germination. The occurrence of the disease is closely related to soil moisture. The bacteria grow well at about 20°C. The soil temperature is low and the seedlings grow slowly, which is conducive to the invasion of bacteria and is easy to be affected. Poorly drained wetlands and soil become heavy and heavy. The special type of faba bean peas, which can invade from the fibrous root, extend to the lateral roots and the main roots, resulting in long brown lesions, making the main root contracture, necrotic roots. Lesions can also extend to the base of the stem, causing the dwarfing of the ground to die.
Control methods (1) Selection of disease-resistant varieties such as Gansu's Gongjing selection, hemp, adzuki bean 60, 704, etc. are more resistant. (2) Seed-dressing seed dressing weight of 0.25% of 20% triadimefon EC or seed dressing of 0.2% of 75% chlorothalonil wettable powder has a certain effect. (3) In the early stage of onset, spray 20% methyl-rhodium phosphorus emulsifiable concentrate 1200 times or 72% DuPont Kelu wettable powder 1000 times, 72.2% Precise (feroxcarb) 400 times liquid, spraying every m2 Good liquid 2-3L, or 95% hymexazol (soil bacteria elimination) fine 4000 times liquid, 3L per m2.
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