Number Of Fungal Propagules Research Articles

Verticillium wilt of chrysanthemum: relative water content and protein, RNA, and chlorophyll levels in leaves in relation to visible wilt symptoms

Shifts in host metabolism during early stages of foliar infection and symptom development are examined. Verticillium dahliae Kleb. invaded and colonized chrysanthemum leaf tissue before symptom expression. Similar numbers of fungal propagules were recovered from non-symptomatic and symptomatic parts of a leaf lobe. No changes in relative water content, tissue permeability, RNA, and protein levels and only a slight decrease in chlorophyll level were detected within infected leaf tissue before the appearance of visible wilt. These data are discussed in relation to the possible role of senescence in the Verticillium wilt syndrome in chrysanthemum.

Mycoecology of willow and cottonwood lowland communities in Southern Wisconsin I. Soil microfungi in the willow-cottonwood forests.

A survey of the soil microfungi in 5Salix nigra-Populus deltoides forests in southern Wisconsin was conducted. The dilution plate method was employed to obtain 500 isolates per stand. The species present and their frequencies of occurrence were determined. The dominant forms,Trichoderma viride, Cladosporium cladosporioides, Gliocladium roseum, Mucor hiemalis, Coniothyrium sp. 5154,Mortierella minutissima, andPenicillium thomii, accounted for 41 % of the 2,500 isolates but only 4.5 % of the 154 species. They were followed at a second level of prevalence byPenicillium janthinellum P. multicolor, Mortierella alpina, andPhoma sp. 5157. The distribution of these taxa and others in the willow-cottonwood community was found to be correlated with an organic matter gradient. The Dematiaceae and the Sphaerioidaceae characterized populations obtained from the dry “pioneer” sites; the Mucorales and Moniliaceae became increasingly abundant as the percentage of organic matter increased. The number of fungal propagules ranged from 3,000 to 234,000 per gram of dry soil, the highest numbers occurring in soils with greater organic matter. The willow-cottonwood microfungal population was most similar to one obtained from soils of the closely related southern Wisconsin wet-mesic forests and least similar to ones isolated from the northern Wisconsin bogs and spruce-tamarack swamps.

The rhizosphere effect shown by some Victorian heathland plants

During the period July 1951 to October 1952, a study was made of the fungai population of the soil of a TVictorian heathland with reference to the rhizosphere effect exerted by five species of native plants growing there. Some 45 genera of fungi with 115 species were isolated; of these, 52 species were obtained from the free soil and the rhizosphere, 25 from the soil only, 27 from the rhizosphere, and 11 species were isolated only from dung. During this period, the numbers of fungal propagules in the free soil, estimated by the dilution-plate technique, varied from 68,500 to 247,600 per gram of oven-dry soil; R/S ratios of 0.6–9.7 were recorded. A study has been made of the antibiotic and cellulose-decomposing activities, and the nutritional requirements, of the mycoflora. Examination of the soil for N-fixing organisms showed that Azotobacter and acid-tolerant aerobes were absent; anaerobes were present in small numbers.