Viability Of Sclerotia Research Articles

Survival of sclerotia of Macrophomina phaseolina and Sclerotium cepivorum after drying and wetting treatments

Exposure of sclerotia of Macrophomina phaseolina to 0 and 33% relative humidity (r.h.) for 12 weeks and of Sclerotium cepivorum to 0, 33 and 55% r.h. for 20 weeks did not reduce their germinability on agar. Exposure to 78% r.h. caused high loss of germinability in M. phaseolina and complete loss in S. cepivorum. After 7-day exposures respective moisture contents of sclerotia of M. phaseolina and S. cepivorum were 1 and 2% at 0% r.h.; and 10 and 14% at 78% r.h. M. phaseolina sclerotia held at 0% and 33% r.h. in desiccators for several times up to 12 days did not decrease in subsequent survivability in moist soil, unlike sclerotia held at 78% r.h. for 4 days. More sclerotia of M. phaseolina were colonized by fungi and Streptomyces spp. on alkaline soil than on acid soil. On alkaline soil twice as many sclerotia were colonized after exposure to 0% r.h. as after exposure to 33, 55 and 78% r.h. Colonization of S. cepivorum sclerotia was as high on acid as on alkaline soil and 3 times as high on sclerotia treated at 0% r.h. as on those treated at higher r.h. Attempts to ascertain the effects of colonization on sclerotial viability were unsuccessful. Incubation of sclerotia of M. phaseolina in moist Rumsford sandy loam (50% m.h.c.) for 20 weeks reduced survivability by 43%. At room temperature, alternate drying and wetting of soil containing sclerotia did not appreciably affect survivability of either pathogen. Survivability of S. cepivorum sclerotia was highest when the sclerotia were incubated in air-dried soil (2–3% m.h.c.) for 20 weeks. Incidence of white rot on onion seedlings transplanted to S. cepivorum-infested soil was higher in soil that had been air-dried for 20 weeks than in soil that had been alternately wetted and dried. Sclerotia that were exposed to 0% r.h. for 7 days before soil incubation produced little white rot.

Sclerotinia sclerotiorum: Viability and Separation of Sclerotia from Soil

Sclerotinia sclerotiorum: Viability and Separation of Sclerotia from Soil

Fungicidal effects of the fumigant dazomet on sclerotia of Sclerotinia sclerotiorum in soil

Dazomet was fungicidal to sclerotia of Sclerotinia sclerotiorum (Lib.) de Bary, from pure culture or collected from different agricultural crops, in soil over a range of temperatures from 5 to 20°C and its effect became operative within 2 days at 20°C ; after 8 days no viable sclerotia were recorded at any of the temperatures. It was more effective in action on sclerotia than either nitrolim or dicyanidiamide which inhibit the formation of stipes and apothecia but do not kill all the sclerotia under the experimental conditions used.

Differential activity of fungicides on various stages in the life cycle of Sclerotinia spp.

Abstract Nine fungicides (benomyl, captan, dichlofluanid, dichlozoline, dicloran, quintozene, thiophanate, thiophanate-methyl, and thiram) were tested for activity against mycelial growth, germination of ascospores and sclerotia, and production of stipes of Sclerotinia minor Jagg, and S. sclerotiorum (Lib.) deBary. Benomyl, dichlozoline, and thiram at 5 ppm caused at least 60% inhibition of mycelial growth of both S. minor and S. sclerotiorum, but the other fungicides were less effective. These were, however, more active against S. sclerotiorum than S. minor, especially thiophanate and thiophanate-methyl. At low concentrations (3-4 ppm) only three fungicides (captan, dichlofluanid, and thiram) completely inhibited germination of ascospores; these three fungicides were fungicidal against ascospores, whereas the other fungicides, particularly dichlozoline, were fungistatic. Viability of sclerotia that were mcubated in suspensions of the fungicides was reduced to 5% for both fungi by benomyl at 1000 ppm and ...

Perpetuation of Species of Cercospora and Ramularia Parasitic on Oilseed Crops

Mode of perpetuation of 4 pathogens viz. Cercospora carthami Sundararaman and Ramakrishnan, Ramularia carthami Zaprometov, Cercospora linicola Pavgi and Rathaiah and Cercospora sesamicola Mohanty inciting leaf spot diseases of safflower, flax and sesame has been investigated. C. carthami and C. linicola perpetuate through a) the vegetative saprobic mycelium and b) viable stromata embedded in the crop debris. R. carthami and C. sesamicola perpetuate only through the viable sclerotia in the crop debris.

Sclerotial Production, Viability Determination and Quantitative Recovery of Sclerotium oryzae from Soil

Sclerotial Production, Viability Determination and Quantitative Recovery of Sclerotium oryzae from Soil

Sclerotial Production, Viability Determination and Quantitative Recovery of Sclerotium Oryzae From Soil

(1972). Sclerotial Production, Viability Determination and Quantitative Recovery of Sclerotium Oryzae From Soil. Mycologia: Vol. 64, No. 6, pp. 1333-1337.

Basidiocarps, annelloconidia, and sclerotia in agar cultures of Pistillaria (Clavariadelphaceae)

Pistillaria micans Fr. and Pistillaria setipes Grev. produced fertile sporophores in agar culture. Light was necessary for production of fertile basidiocarps in both species and for pigment production and conidium formation in P. micans. Annelloconidia were produced by P. micans. Viable sclerotia were formed by P. setipes. The taxonomic significance of sclerotia in Pistillaria and Typhula is discussed. Neither species demonstrated geotropism, but the fruit body of P. setipes was positively phototropic. Temperature optima for growth and sporophore production were ca. 15 °C for P. setipes and ca. 20–22 °C for P. micans.

Studies on sharp eyespot disease of cereals II. Viability of sclerotia: persistence of the causal fungus, Rhizoctonia solani Kühn

SUMMARYSclerotia of Rhizoctonia solani survived for long periods in the laboratory. When left undisturbed in the soil, 79% of buried sclerotia survived for a period of 6 months. Sclerotia retained their infectivity towards seedling wheat plants throughout all viability tests.Sclerotia germinated readily in response to various stimuli and were able to regerminate at least ten times: it is considered that this property enhances their survival value.Although wheat stem isolates decomposed cellulose in pure culture and competitively colonized certain types of cellulose in soil, they were ineffective in colonizing cereal straws in the soil. The pathogen quickly died out in artificially infested soil and showed only limited survival in naturally infected cereal straw buried in soil. In pot experiments the pathogen persisted parasitically under a number of crops.

Host range of the violet root rot fungus, Helicobasidium purpureum pat.

The host range of Helicobasidium purpureum was studied in a glasshouse experiment. Seventeen species, in eight families, developed infection cushions of violet root rot. Over 10 weeks, no greater losses in viability of sclerotia were associated with susceptible roots than with resistant ones. In a study on the effect of root systems on germination of sclerotia, Lotus comiculatus , a resistant species, induced a significant increase in germination in 10 weeks. Trifolium pratense , a susceptible species, significantly reduced the percentage of germination, compared with a control series in fallow soil.

THE OCCURRENCE OF VIABLE COTTON ROOT-ROT SCLEROTIA IN NATURE

Viable sclerotia of the cotton root-rot fungus, Phymatotrichum omnivorum, have been found under natural conditions in the soil of infested cotton fields in Texas, showing that this fungus is a soil organism not restricted to living roots of susceptible host plants, but having an independent means of over-wintering and dissemination.