Effect Of Spore Concentration Research Articles

Effect of spraying adjuvants with the biocontrol fungus Microsphaeropsis ochracea at different water volumes on the colonization of apple leaves

In a previous study, it was observed that Microsphaeropsis ochracea was less efficacious as a biofungicide for apple scab when applied under field conditions as an unformulated spore suspension with an airblast spray using low water volumes as compared to a ground cover spray using high water volumes. The effect of spore concentration (109 to 1012 spores ha−1), water volume (250–1500 L ha−1), and 20 adjuvants were studied to improve colonization of apple leaves by M. ochracea. Using commercial-type spray equipment, the fungus was applied to excised apple leaves. Higher spores concentrations resulted in greater colonization. Water volume did not have a strong impact on colonization. Only a few adjuvants improved germination (glycerine) and mycelial growth (K-90, Agrimer, Ekol, and Tween 80) in some trials. When tested on apple trees, the adjuvant Assist provided the most consistent improvement in colonization in five out of eight trials. The use of oils, humectants, and surfactants could broaden the opportunities for using this biofungicide.

Formation of the spore clumps during heat treatment increases the heat resistance of bacterial spores

Effects of the clumping of bacterial spores on their heat resistance as a result of heat treatment were investigated. Spore suspensions of Bacillus cereus, Bacillus coagulans and Bacillus licheniformis were heated at 85 °C. Survivor curves of the three strains showed tailing in all treatments after 30 min. As the treatment time increased, the formation of spore clumps increased in all strains after 20 min. Relative hydrophobicity of the spore surface increased as a result of heat treatment. The effect of spore concentration on the inactivation of the B. licheniformis spores was investigated, and surviving curves showed no tailing below a concentration of 4.9 log CFU/ml.

Interspecific competition between the nematode-trapping fungus, Duddingtonia flagrans, and selected microorganisms and the effect of spore concentration on the efficacy of nematode trapping.

The fungus, Duddingtonia flagrans, is able to trap and kill free-living nematode larvae of the cattle parasite Cooperia oncophora when chlamydospores are mixed in cattle faeces. Isolates of Bacillus subtilis (two isolates), Pseudomonas spp. (three isolates) and single isolates of the fungal genera Alternaria, Cladosporium, Fusarium, Trichoderma and Verticillium were isolated from cattle faeces and shown to reduce D. flagrans growth on agar plates. When these isolates were added to cattle faeces containing D. flagrans and nematode larvae of C. oncophora, developing from eggs, none of the isolates reduced nematode mortality attributed to D. flagrans. Similarly, the coprophilic fungus Pilobolus kleinii, which cannot be cultivated on agar, also failed to suppress the ability of D. flagrans to trap and kill developing larvae of C. oncophora. Increasing chlamydospore doses of D. flagrans in faecal cultures resulted in higher nematode mortality. Thus, no evidence of interspecific or intraspecific competition was observed. The consequences of these findings are discussed.

Effect of inoculum density and borate concentration in a stump treatment trial against Heterobasidion annosum

Summary The effectiveness of disodium octaborate tetrahydrate (DOT) as a stump treatment chemical for Sitka spruce in Britain was tested on six occasions by inoculating treated and untreated stumps with basidiospores of Heterobasidion annosum at three concentrations ranging from an average 49 viable spores/ml to 4.9 × 105/ml of water. The extent of colonization of heartwood by H. annosum was measured and, along with the incidence of infected stumps, provided a measure of the combined effects of spore concentration and of the two DOT treatments (15 and 30 g/m2) on the trial results. On untreated stumps, both the incidence of infection and the cross-sectional area of stump heartwood colonized by the fungus increased with inoculum density. The same effect was evident in treated stumps, but it was reduced by increasing DOT application. Infection was at its lowest in stumps treated with DOT at 30 g/m2, being entirely absent from those 60 stumps that were inoculated with the fewest spores. The implications of these findings for the design of trials of control agents that rely on artificial inoculation with H. annosum and for the selection of dose rates to use in harvesting operations are discussed.

Some Factors Affecting the Germination of Thermoascus aurantiacus Ascospores

Studies were done to determine the cardinal temperatures for germination, as well as the effects of spore concentration and tube culture age on the germination of ascospores from Thermoascus aurantiacus. The minimum, optimum, and maximum temperatures for germination were 32.5–35 C, 47.5 C, and 60 C, respectively. Percent germination was affected slightly by culture age, and a statistically significant increase in percent spore germination occurred when the concentration was increased to 1 million per milliliter.

Effects of Spore Concentration, Temperature, and Dew Period on Disease of Field Bindweed Caused byPhoma proboscis

Spore germination of Phoma proboscis in vitro and resulting disease development were evaluated over a range of spore concentrations and after incubation at nine dew periods at each of five temperatures. Reduced percent germination on water agar occurred at spore concentrations above 10 7 spores ml -1 . Spore germination on agar was optimal at 24C (...)

Effect of spore concentration on germination and autotropism inTrichoderma hamatum

Effect of spore concentration on germination and autotropism inTrichoderma hamatum