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 Posted: Sun 11:48, 30 Jan 2011 Post subject: Rot disease of lettuce in Tianshui City, and the d |
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Rot disease of lettuce in Tianshui City, and the damages of
, The strain began to increase; when the temperature is 22.3 ℃, the rapid rise in the soft rot type strain, strain rate 34.19,5. Microscopic examination showed that the short rod cell, week 2 to 8 flagella of Health, for the soft rot Erwinia EErwiniaCarotovora (JOHES) Holland-1 infection due. ② wither and die type strain. Susceptible plants and early brown spots, up from the roots or petioles spreading gradually extended to the leaves wilt and dry,[link widoczny dla zalogowanych], irrigation lesion before the more common yellow, brown, after irrigation, roots or petioles are produced filamentous hyphae . Its occurrence is when the temperature l1.4 ℃, the disease began; when the temperature rose to 15.6 ℃, the strain increased; when the temperature is 19.8 ℃, the strain rate is not only increased, reaching 38.69, 5, and the strain of filamentous mycelium on the increase. Microscopic examination showed that the pathogen Rhizoctonia solani (Rhizoc-toniasolanikUhn) as Amon of imperfect fungi, Rhizoctonia fungus invasion caused. ③ rancid type strain atrophy. Department of susceptible plants before the foundation of the soft reduction, 3 ~ 9d after the odor. Examination results, the harvest rate of 25.3 of strain, the two pathogenic fungi and bacteria have infected. 2.2 Field symptoms and onset of disease symptoms occurs 2.2.1 Daejeon Daejeon type symptoms consistent with greenhouse observations, there are 3 types of the disease. But in different vegetable area, the occurrence of 3 types of strain and damage to varying degrees. Some strains of the main places to soft rot, bacterial heavy damage; some places, mainly to wither and die plants, fungi, heavy damage; but later atrophy rancid type strain appeared in general to the late harvest or growth, diseased plants rate is low. 2.2.2 Field disease incidence and transmission of disease re-Autumn and Winter lettuce, spring lettuce crop incidence of light. Exposed to harmful levels of morbidity and serious than the protected area. Protected cultivation generally from 2 months, late onset, in late March to April, the middle of entering Sheng, strain rate 28.3oA; exposed to Planting in late July or August to start in early disease, in August incidence between late September to enter the peak of the average strain rate of 34.5. Soft rot bacteria in sick deformed, weeds, contaminated soil and fertilizer in the winter, is not decomposed by bacteria in the manure, irrigation, insects and the spread of the invasion from the wound. Rhizoctonia mycelia and sclerotia in the soil sick deformed or winter, depending on irrigation, application of manure, and other manual means of communication. Humid warmth, high planting density, light plots with poor ventilation and incidence of weight, applied not fully decomposed organic manure plots incidence of weight. 2.3 Cultural factors of diseases in germination 2.3.1 Soaking the same species on the impact of disease in the same conditions, cultivation management, soil, and disinfection after 3 to 4 true leaves of seedlings, seeds were soaked 7 seedbed sowing germination, due to high seed germination, plant disease resistance increase, the average strain rate 11.69,5, while untreated seeds average strain rate of 4 beds 19.49,[link widoczny dla zalogowanych],5, soaking more Soaking is not low incidence of 7.8 percentage points. 2.3.2 Disinfection of soil shed the influence of the disease shed body sterilized soil treated l1 a shed, the average strain rate of 9.49,5, and shed 7 untreated, the average strain rate of 15.1 , disinfection disinfection than the average incidence rate is not 5.7 percent, and there l1 center of a diseased plant disinfection shed more time than non-sterile shelf late 5 ~ 8d. 2.3.3 Different Irrigation Methods on the impact of disease and the membrane under small furrow irrigation of 9 to the average strain rate of 4.5, the average yield loss 3.8oA, and flood irrigation of seven to an average strain rate of 7 .29,5, the average yield loss of 6.99,5, and the membrane under small furrow irrigation water flooding the larger the average strain rate of 2.7 percentage points lower,[link widoczny dla zalogowanych], the average yield loss decreased 3.1 percentage points. 3.1 Summary of findings 3 that occurred in the greenhouse and field type of soft rot, wither and die type,[link widoczny dla zalogowanych], atrophy rancid strain of 3 classes, which pathogenic preliminary examination results were Erwinia soft rot, Rhizoctonia bacteria and both. In the greenhouse, with temperature rise, strain gradually increased; field planting, the spring crop of light incidence, morbidity Autumn and Winter weight, exposed to harmful levels of morbidity and serious than the protected area. 3.2 the same species, cultivation and management in the same conditions, the soil, and disinfection, the soaking treatment, the average strain rate, without soaking treatment,[link widoczny dla zalogowanych], the average strain rate and low incidence of soaking than 7.8 without soaking percentage points. Sterilized soil shed body, the average strain rate lower than 5.7 percentage points is not disinfected, and the center of strain occurs later than 5 ~ 8d. Under small furrow irrigation and the average strain rate of membrane water flooding low of 2.7 percentage points higher, the average yield loss decreased 3.1 percentage points. (This article Zebian: Zhang Xueqin)
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