Leaf spot of bananas caused by Mycosphaerella musicola: action of oil on the life cycle of the pathogen

1968 ◽  
Vol 46 (12) ◽  
pp. 1495-1505 ◽  
Author(s):  
R. H. Stover ◽  
J. D. Dickson
Keyword(s):  
Incubation Period ◽  
Leaf Spot ◽  
Germ Tube ◽  
Tube Growth ◽  
Disease Development ◽  
Resistant Varieties ◽  
Mycosphaerella Musicola ◽  
Appressoria Formation ◽  
Ascospore Production ◽  
Germ Tube Growth

Oil spray reduced germination, germ tube growth, and appressoria formation by spores of Mycosphaerella musicola under field conditions for periods varying from 2 days to 2 weeks. Inhibition occurred only when spores were on the same leaf surface to which oil was applied. Appressoria formation and germ tube growth were reduced up to 33% and 25%, respectively. Conidia and ascospore production and dissemination were not adversely affected by oil spray. However, there were fewer sporodochia and perithecia in spots that were slow to develop as a result of oil spray. Oil application up to 2 weeks before or after infection increased the incubation period and the generation time, and reduced the number of spots. Oil is effective in retarding spot development when applied either before streaks appear or at the yellow streak stage of disease development. Oil, when applied during the incubation period or to yellow streaks, causes a variable amount of reduction in spotting and in only a minority of cases is disease development stopped completely. Therefore, leaf spot can build up on oil-sprayed plants when inoculum is abundant and weather favorable. The behavior of the pathogen on oil-sprayed susceptible banana plants is similar to that on partially resistant varieties.

scholarly journals Effect of Temperature on Thekopsora minima Urediniospores and Uredinia

Plant Disease ◽  
2004 ◽  
Vol 88 (4) ◽  
pp. 359-362 ◽  
Author(s):  
S. E. Pfister ◽  
S. Halik ◽  
D. R. Bergdahl
Keyword(s):  
Incubation Period ◽  
Germ Tube ◽  
Polynomial Regression ◽  
Tube Growth ◽  
Effect Of Temperature ◽  
Optimum Temperature ◽  
Infection Efficiency ◽  
Percent Germination ◽  
Leaf Disks ◽  
Germ Tube Growth

Thekopsora minima is a heteroecious rust, with spermogonia and aecia occurring on the needles of hemlock (Tsuga spp.) and uredinia, telia, and basidia occurring on the leaves of ericaceous genera, including species of Rhododendron. The effect of temperature was determined for urediniospore germination, germ tube growth, and infection efficiency on Rhododendron ‘White Lights’. Percent germination and germ tube growth were assessed at 10, 15, 20, 25, and 30°C after 3 h of incubation on 1.5% water agar in the dark. Polynomial regression analyses revealed a significant effect of temperature on both germination (P < 0.001, R2adj = 0.936) and germ tube growth (P < 0.001, R2adj = 0.933), with predicted optimum temperatures of 21.5 and 22.0°C, respectively. Germination and germ tube growth were reduced greatly at 30°C and below 15°C. Temperature also was found to have a significant effect on infection efficiency, as measured by incubation period (P < 0.001, R2adj = 0.808) and uredinia produced (P < 0.001, R2adj = 0.866). On excised leaf disks of Rhododendron ‘White Lights’ maintained under a 14-h photoperiod, the shortest mean incubation periods of 10.7 and 10.0 days were at 20 and 25°C, respectively, with a predicted optimum of 23°C. The mean incubation period at 15 and 30°C was approximately 4 and 3 days longer, respectively, than at the predicted optimum temperature. The number of uredinia produced was similar at 15, 20, and 25°C, but was reduced sixfold at 30°C. The predicted optimum temperature for uredinial production was 19.5°C, with a 5% variation in uredinia production between 17.5 and 22°C.

Constitutive Coumarin Accumulation on Sunflower Leaf Surface Prevents Rust Germ Tube Growth and Appressorium Differentiation

Crop Science ◽  
2007 ◽  
Vol 47 (3) ◽  
pp. 1119-1124 ◽  
Author(s):  
E. Prats ◽  
M. J. Llamas ◽  
J. Jorrin ◽  
D. Rubiales
Keyword(s):  
Germ Tube ◽  
Leaf Surface ◽  
Tube Growth ◽  
Germ Tube Growth

Effect of light exposure on in vitro germination and germ tube growth of eight species of rust fungi

Mycologia ◽  
2010 ◽  
Vol 102 (5) ◽  
pp. 1134-1140 ◽  
Author(s):  
James W. Buck ◽  
Weibo Dong ◽  
Daren S. Mueller
Keyword(s):  
Germ Tube ◽  
Light Exposure ◽  
Rust Fungi ◽  
Tube Growth ◽  
In Vitro Germination ◽  
Effect Of Light ◽  
Germ Tube Growth

Factors influencing infection, colonization and symptom expression in barley by Rhynchosporium secalis

1974 ◽  
Vol 25 (1) ◽  
pp. 9 ◽  
Author(s):  
SM Ali
Keyword(s):  
High Temperature ◽  
Germ Tube ◽  
Leaf Tissue ◽  
Tube Growth ◽  
Rhynchosporium Secalis ◽  
Symptom Expression ◽  
West China ◽  
Effects Of Temperature ◽  
Resistant Genotypes ◽  
Germ Tube Growth

Germ tube growth and mycelium establishment of Rhynchosporium secalis, the causal agent of scald in barley, were studied in seven resistant and four susceptible barley hosts of known genotype. Although no visible symptoms were apparent, none of the resistant hosts were free from mycelium establishment in leaf tissue. The resistant hosts could be divided into two categories according to the rate of germ tube growth. The effect of host age, duration of incubation period, temperature, spore concentration, and pathogen age on symptom expression in the 11 genotypes was examined. Excluding the effects of temperature, the resistant genotypes could be grouped into (a) those expressing their resistance consistently, e.g. Psaknon, Atlas 46, Atlas 57, Hudson and Turk, and (b) those expressing their resistance inconsistently, e.g. West China and La Mesita. High temperature caused breakdown of resistance in Psaknon, Turk, Hudson and West China. The pathogenicity of one isolate (UWA307) was found to be impaired by high temperature. Implications of the above findings are discussed in relation to the disease situation in Western Australia.

The effect of temperature on in vitro germination and germ tube growth of urediniospores of Tranzschelia discolor

1990 ◽  
Vol 41 (3) ◽  
pp. 479 ◽  
Author(s):  
PJ Ellison ◽  
BR Cullis ◽  
RW Bambach ◽  
PF Kable
Keyword(s):  
Germ Tube ◽  
Three Dimensional ◽  
Tube Growth ◽  
Effect Of Temperature ◽  
In Vitro Germination ◽  
Three Dimensional Models ◽  
C 30 ◽  
Tranzschelia Discolor ◽  
Germ Tube Growth

The effect of temperature on in vitro germination and germ tube growth of urediniospores of Tranzschelia discolor was studied over time under constant temperature conditions. Studies were carried out on 1% water agar in the dark at 3�C, 5�C, 8�C, 10�C, 15�C, 20�C, 25�C, 28�C, 30�C and 32�C. Germination was observed at all temperatures between 5 and 30'C, and occurred rapidly over most of this range. At 2 h, germination exceeded 80% at temperatures between 10 and 28�C, and this level was reached at 3 h at 8�C. Germination at 5 and 30�C was much reduced and at 7 h reached only 44% and 38% respectively. Germ tube growth occurred most vigorously at 15 and 20�C, reaching lengths in excess of 500 8m at 9 h. The optimum range was narrower than that for germination, and growth was reduced or poor at 8�C, 10�C, 25�C and 28�C, which were favourable temperatures for germination. Average germ tube lengths at 9 h at these temperatures were 55, 245, 273 and 62 8m, respectively. Three-dimensional models were derived relating germination and germ tube growth to time and temperature.

Production of extracellular enzymes by germinating cysts of Phytophthora infestans

1985 ◽  
Vol 63 (10) ◽  
pp. 1811-1816 ◽  
Author(s):  
Robert A. Moreau ◽  
Thomas S. Seibles
Keyword(s):  
Phytophthora Infestans ◽  
Esterase Activity ◽  
Time Course ◽  
Germ Tube ◽  
Extracellular Enzymes ◽  
Hydrolytic Enzymes ◽  
Tube Growth ◽  
Metabolic Inhibitors ◽  
Time Course Study ◽  
Germ Tube Growth

Cysts of Phytophthora infestans were prepared and allowed to germinate in water for 0 to 20 h. The activities of 11 different types of hydrolytic enzymes were detected in the extracellular germination medium. A time-course study revealed that most of the enzyme activities increased very little during germination. However, esterase activity increased 45-fold during germination. The rate of appearance of esterase activity closely paralleled the rate of germ tube growth. The intracellular levels of esterase activity were low throughout germination. These observations suggest that esterase is secreted during germination. Cysts also were allowed to germinate in the presence of various potential metabolic inhibitors and their effect on the appearance of esterase activity and on germ tube growth was measured. With each compound that inhibited the rate of germ tube growth, there was a nearly proportionate inhibition in the rate of appearance of extracellular esterase.

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