scholarly journals Epidemiology of Bacteral Canker of Kiwifruit. 4. Optimum Temperature for Disease Development on New Canes.

1993 ◽  
Vol 59 (6) ◽  
pp. 694-701 ◽  
Author(s):  
Setsuo SERIZAWA ◽  
Takeshi ICHIKAWA
Keyword(s):  
Disease Development ◽  
Optimum Temperature

scholarly journals Differences Between Ascospores and Conidia of Didymella rabiei in Spore Germination and Infection of Chickpea

2007 ◽  
Vol 97 (12) ◽  
pp. 1600-1607 ◽  
Author(s):  
Antonio Trapero-Casas ◽  
Walter J. Kaiser
Keyword(s):  
Disease Severity ◽  
Spore Germination ◽  
Opposite Effect ◽  
Disease Development ◽  
Optimum Temperature ◽  
Water Potentials ◽  
Wetness Period ◽  
Moisture Conditions ◽  
Germ Tubes ◽  
Plant Surfaces

Studies were performed to compare the germination and infection of ascospores and conidia of Didymella rabiei under different temperature and moisture conditions. Germination of ascospores and conidia on cover glasses coated with water agar began after 2 h, with maximum germination (>95%) occurring in 6 h at 20°C. No germination occurred at 0 and 35°C. Ascospores germinated more rapidly than conidia at all temperatures. Germination declined rapidly as the water potential varied from 0 to –4 MPa, although some germination occurred at –6 MPa at 20 and 25°C. Ascospores germinated over a wider range of water potentials than conidia and their germ tubes were longer than those of conidia at most water potentials and temperatures. The optimum temperature for infection and disease development by both ascospores and conidia was around 20°C. Disease severity was higher when ascospores were discharged directly onto plant surfaces from naturally infested chickpea debris compared with aqueous suspensions of ascospores and conidia sprayed onto plants Disease severity increased as the length of the wetness period increased. When dry periods of 6 to 48 h occurred immediately after inoculation, disease severity decreased, except for the shorter periods which had the opposite effect. Disease severity was higher with ascospore inoculum when no dry periods occurred after inoculation.

scholarly journals The Effects of Temperature and Wetness Period on the Development of Spinach White Rust

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 753-758 ◽  
Author(s):  
M. J. Sullivan ◽  
J. P. Damicone ◽  
M. E. Payton
Keyword(s):  
Disease Severity ◽  
Temperature Effects ◽  
Multiple Regression Model ◽  
Disease Development ◽  
Optimum Temperature ◽  
Influence Of Temperature ◽  
White Rust ◽  
Wetness Period ◽  
Controlled Environments ◽  
Effects Of Temperature

Experiments were conducted in controlled environments to determine the influence of temperature and duration of wetness on development of white rust of spinach. Plants of the susceptible cv. Kent were exposed to temperatures of 6 to 28°C and interrupted wetness periods that totaled 3 to 84 h following inoculation. Disease severity was assessed following further incubation in a greenhouse at 20 to 30°C. Disease was observed at all temperatures and increased with wetness duration. The optimum temperature for disease development ranged from 12 to 18°C. Only 3 h of wetness were required for disease development at 12 to 22°C. A minimum wetness period of 6 to 12 h was required for disease development at suboptimal temperatures. A multiple regression model describing the response surface of arcsine square root transformed disease severity was developed that had significant quadratic wetness effects, cubic temperature effects, and interaction between temperature and wetness. The resulting polynomial model provided a good fit to the observed data, accounting for 89% of the variation in transformed disease severity.

FACTORS AFFECTING INFECTIVITY OF VAIRIMORPHA NECATRIX (MICROSPORIDIA: NOSEMATIDAE) IN TRICHOPLUSIA NI (LEPIDOPTERA: NOCTUIAE)

1981 ◽  
Vol 113 (2) ◽  
pp. 93-102 ◽  
Author(s):  
Wei Hsuang Chu ◽  
Robert P. Jaques
Keyword(s):  
Trichoplusia Ni ◽  
Cabbage Looper ◽  
Artificial Light ◽  
Disease Development ◽  
Optimum Temperature ◽  
Factors Affecting ◽  
Rate Of Development ◽  
Time To Death ◽  
Third Instar Larvae

AbstractIngested dosages of 10.9 and 16.5 spores of Vairimorpha necatrix (Kramer) 7 and 27 weeks old, respectively, killed 50% of third-instar larvae of the cabbage looper, Trichoplusia ni (Hübner). Time to death of 50% of larvae (LT50) decreased from 14 to 3 days with increases in dosage from 5 × 101 to 5 × 106 spores (2-week-old)/Iarva. The LT50 for 5 × 101 spores/larva increased from 14 to 25 days with storage of spores at 4°C for 2 and 93 weeks, respectively. Spores applied to soil lost little activity during cool weather but spores applied in summer were inactivated within 60 days. Desiccation or exposure to sunlight or artificial light inactivated the spores. Rate of development of disease was increased by feeding host larvae a diet containing increased proportions of casein or sucrose. The optimum temperature for disease development in T. ni was 25°C.

Urdbean web blight and its management strategies- A review

2018 ◽  
Author(s):  
Santosh Kumar ◽  
Amarendra Kumar Rolling Anal ◽  
H. S. Tripathi
Keyword(s):  
Relative Humidity ◽  
Management Strategies ◽  
Molecular Characteristics ◽  
Disease Development ◽  
Optimum Temperature ◽  
Yield Losses ◽  
Culture Morphology ◽  
Abiotic Constraints ◽  
Web Blight ◽  
Heavy Rains

The production and productivity of urdbean ranks lower in India as compared to the that of world average due to the biotic and abiotic constraints. Web blight of Urdbean is caused by Rhizoctonia solani Kuhn and is a soil borne pathogen and initial inoculums come mainly from soil splashes which fall on leaves during heavy rains. Respective optimum temperature and relative humidity i.e. 26–28oC and 90–100% favours disease development chronically. The pathogen can survive very longer in the absence of a host either as sclerotia or thick walled brown hyphae in plants debris. Currently the disease is prevalent in many countries across the globe. The pathogen is highly variable in terms of its pathogenicity, culture, morphology, biochemical and molecular characteristics. The severity of this disease is directly linked with the population of viable sclerotia in the soil. Yield losses due to this disease vary in between 20-30% depending upon prevailing conditions.

scholarly journals Effects of Humidity on the Development of Grapevine Powdery Mildew

2003 ◽  
Vol 93 (9) ◽  
pp. 1137-1144 ◽  
Author(s):  
J. E. Carroll ◽  
W. F. Wilcox
Keyword(s):  
Powdery Mildew ◽  
Management Practices ◽  
Absolute Humidity ◽  
Uncinula Necator ◽  
Disease Development ◽  
Optimum Temperature ◽  
Test Range ◽  
Grapevine Powdery Mildew ◽  
Conidium Germination

The effects of humidity on powdery mildew development on grape seedlings and the germination of Uncinula necator conidia in vitro were examined. Studies were conducted at an optimum temperature of 25 ± 2°C. Disease on foliage was markedly affected by humidity levels in the test range of 39 to 98% relative humidity (RH), corresponding to vapor pressure deficits (VPD) of 1,914 to 61 Pa. Incidence and severity increased with increasing humidity to an optimum near 85% RH, and then appeared to plateau or decrease marginally at higher values. Conidial density and chain length also were proportional to humidity, but were influenced less strongly. There was a strong, positive linear relationship between humidity level and frequency of conidium germination with RH treatments of ≤84%. However, germination frequency fell sharply at RH levels above a mean of 87%. All measures of humidity were equally accurate in predicting germination responses; however, VPD was slightly more effective than RH in accounting for effects on disease development and pathogen sporulation, and both were more effective than absolute humidity. Humidity appears to play a significant role in grapevine powdery mildew epidemiology, confirming the benefits of management practices to avoid and mitigate high humidity in the vineyard canopy.

STUDIES IN FOREST PATHOLOGY: XXIV. POLYPORUS TOMENTOSUS FR. AS A MAJOR FACTOR IN STAND-OPENING DISEASE OF WHITE SPRUCE

1962 ◽  
Vol 40 (12) ◽  
pp. 1631-1658 ◽  
Author(s):  
R. D. Whitney
Keyword(s):  
Competitive Advantage ◽  
Rhizoctonia Solani ◽  
Disease Development ◽  
Forest Pathology ◽  
Phytophthora Cactorum ◽  
Optimum Temperature ◽  
Root Tips ◽  
Root Decay ◽  
Dead Trees ◽  
Optimum Ph

Stand-opening disease in Saskatchewan spruce forests is characterized by the occurrence of patches, often of an acre or more, of declining and dead trees. Polyporus tomentosus Fr. is a major cause of the disease, which develops slowly, with 20 to 30 years elapsing between initiation of attack and death of the trees. Extensive root decay develops before the above-ground symptoms become apparent. Inoculation experiments have shown that P. tomentosus grows about 1.5 in. per year, and that the fungus is parasitic on white spruce.Polyporus tomentosus may enter healthy roots at a point of contact with infected roots; no evidence was found that it entered through root tips or directly from the soil. The fungus remains viable in infected roots for at least 16 years. The disease is commonly associated with injury caused by root-tunnelling weevils in the genus Hylobius. Host vigor did not appear to influence infection or disease development. In culture, the optimum temperature for P. tomentosus was 20 °C and the optimum pH was 4.5. At lower temperatures P. tomentosus appeared to have a competitive advantage over fungi isolated from dying rootlets. Small seedlings grown in agar with P. tomentosus were killed in 8 months. Under these conditions P. tomentosus was much less virulent than Rhizoctonia, solani Kühn and Phytophthora cactorum L. and C. Schroet.

RESISTANCE TO MILDEW OF SELECTION FAMILY OF RED CURRANT THE BELAYA POTAPENKO × № 1426-21-80

1970 ◽  
pp. 38-40
Author(s):  
O. O. Kalinina ◽  
O. D. Golyaeva ◽  
O. V. Panfilova ◽  
А. V. Pikunova
Keyword(s):  
Powdery Mildew ◽  
Field Resistance ◽  
Disease Development ◽  
Artificial Infection ◽  
Sources Of Resistance ◽  
Climate Conditions ◽  
High Productivity ◽  
Local Soil ◽  
The Family ◽  
Red Currant

Powdery mildew is one of the most harmful fungal diseases that causes economically significant damage to berry plantations. The disease is common in all areas of currant cultivation in the Russian Federation. In this regard, in modern conditions of intensive berry growing, the problem of breeding cultivars that are highly resistant to diseases and pests becomes urgent. Breeders have a difficult task to combine the adaptive potential of the cultivar with its annual high productivity and resistance to biotic environmental factors. When studying the adaptability of introduced cultivars of red currant and selected forms of the Institute to local soil and climate conditions, the following cultivars were identified as sources of economic and useful characteristics and involved in selection: ‘Belaya Potapenko’ as a complex source of resistance powdery mildew and high marketable and taste qualities of berries; SS 1426-21-80 as a source of high productivity and long racemes (raceme length 11-13 cm; up to 20 berries in the raceme). On their base the selection family of red currant has been developed: Belaya Potapenko × ♂SS 1426-21-80. The study of data on the destruction of hybrid seedlings of the selection family by powdery mildew showed that in epiphytotic conditions, the percentage of intensity of the disease development varies over the periods of screening from 0.2% in May to 20.4% in June. Such indicators served as a prerequisite for conducting a comparative test of breeding material in the field under artificial infection with powdery mildew. After artificial infection on the background of epiphytosis, the rate of intensity of the disease development increased slightly and amounted to 35.6% for the family. There were 30 highly resistant seedlings in the family, 10 of which have remained stable and highly resistant since 2018. In these plants we can assume the presence of the so-called field resistance, controlled by polygens, each of which does not give a visible effect of stability, but with different combinations determines one or another of its degree. Highly resistant seedlings will be used in further breeding studies to identify new sources of resistance to powdery mildew.

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