scholarly journals Survival, Germination, and Growth of Epichloë typhina and Significance of Leaf Wounds and Insects in Infection of Orchardgrass

Plant Disease ◽  
2013 ◽  
Vol 97 (3) ◽  
pp. 323-328 ◽  
Author(s):  
Stephen C. Alderman
Keyword(s):  
Water Potential ◽  
Infection Process ◽  
Effect Of Temperature ◽  
Ascospore Germination ◽  
Eriophyid Mites ◽  
Epichloë Typhina ◽  
Dry Conditions ◽  
Significant Yield ◽  
Germination And Growth ◽  
Germ Tubes

Epichloë typhina is an important stroma-producing endophytic ascomycete that is responsible for significant yield loss in orchardgrass (Dactylis glomerata) seed production fields. Infection is presumed to occur through leaves or stems, although details of the infection process and conditions that favor leaf infection are not well understood. The primary objectives of this study were to investigate the early stages of infection, including the effect of temperature or water potential on ascospore germination and subsequent growth of E. typhina, the tolerance of ascospores to desiccation, the requirement of leaf wounds for infection of orchardgrass by E. typhina, and the potential for insects to facilitate infection. Ascospores tolerated dry conditions, with at least 40% surviving 12 days under desiccation. Germination and growth of E. typhina was greatest at 25°C, with little to no growth at 5 and 35°C. Mycelial growth decreased with decreasing water potential from –0.3 to –10 MPa. Ascospore germination on leaves was predominantly hyphal at wound sites and iterative (conidiogenous) at sites without wounds. E. typhina typically entered leaves through wounds. Direct penetration was rarely observed and appeared to be associated with ascospore clusters. Germ tubes were significantly longer at sites with honeydew deposits from the bird cherry–oat aphid than at sites without honeydew. Growth of E. typhina was also observed at feeding sites of eriophyid mites, suggesting that leaf-wounding or sap-excreting insects support epiphyllous growth of E. typhina on leaves.

scholarly journals Effect of Temperature on the Discharge and Germination of Ascospores by Apothecia of Monilinia fructicola

Plant Disease ◽  
1998 ◽  
Vol 82 (2) ◽  
pp. 195-202 ◽  
Author(s):  
Chuanxue Hong ◽  
Themis J. Michailides
Keyword(s):  
Management Strategies ◽  
Brown Rot ◽  
Effect Of Temperature ◽  
Monilinia Fructicola ◽  
Stone Fruits ◽  
Warning Systems ◽  
Fresno County ◽  
Ascospore Germination ◽  
Daily Discharge ◽  
Germ Tubes

Naturally growing apothecia of Monilinia fructicola were collected from two commercial plum orchards near Reedley and Sanger, both in Fresno County, California. Ascospore discharges from 90 (1996) and 86 (1997) apothecia were monitored individually using spore traps at four constant temperatures. The period of discharge decreased as temperature increased from 10 to 25°C. However, daily discharge increased as temperature increased from 10 to 15°C and remained high at 20 and 25°C. The greatest discharge occurred with apothecia at 15°C, followed by those incubated at 20, 10, and 25°C. The germination of ascospores of M. fructicola and the length of germ tubes increased as temperature increased from 7 to 15°C; however, increasing temperatures above 15°C did not increase either ascospore germination or length of germ tubes. This information may help in the development of warning systems and management strategies for brown rot blossom blight of stone fruits.

Effects of Temperature and Moisture on Conidia Germination, Infection and Acervulus Formation of Apple Marssonina Leaf Blotch Pathogen (Diplocarpon mali) in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Sen Lian ◽  
Xiang-li Dong ◽  
Pingliang Li ◽  
Caixia Wang ◽  
shanyue zhou ◽  
...  
Keyword(s):  
Severe Disease ◽  
Infection Process ◽  
Effect Of Temperature ◽  
Leaf Wetness ◽  
Leaf Blotch ◽  
Dry Conditions ◽  
Conidium Germination ◽  
Effects Of Temperature ◽  
Epidemic Development ◽  
Diplocarpon Mali

Apple marssonina leaf blotch (Diplocarpon mali) is a severe disease of apple that mainly causes premature leaf defoliation in many apple growing areas in the word. Its epidemic development is closely related to temperature and rainfall. The effects of temperature and moisture on conidium germination, infection on leaves, and acervulus production were investigated under controlled environments. Temperature required for conidium germination and infection ranged from 5 oC to 30 oC with the optimum around 23 oC, and temperature required for acervulus formation was slightly wider with the optimum at 24.6 oC. Wetness was needed for conidia to germinate and infect; only few conidia germinated at RH=100%. However, lesions can produce acervuli in dry conditions. The minimum duration of leaf wetness required for conidia to complete the entire infection process were 14, 8, 4, and 6 hours at 10, 15, 20, and 25°C, respectively. A model describing the effect of temperature and leaf wetness duration was built. The model estimated that conidial infection has the optimum temperature at 22.6°C and the minimum wetness duration required of 4.8 hours. The model can be used to forecast the conidial infection of D. mali to assist in disease management in commercial apple production.

Low-temperature requirements for ascospore germination and growth of Hypoxylon diathrauston

1970 ◽  
Vol 48 (12) ◽  
pp. 2223-2225 ◽  
Author(s):  
G. B. Ouellette ◽  
E. W. B. Ward
Keyword(s):  
Low Temperature ◽  
Ascospore Germination ◽  
Temperature Requirements ◽  
Freezing Temperatures ◽  
Germination And Growth ◽  
Germ Tubes

Ascospores of Hypoxylon diathrauston Rehm germinated only at freezing temperatures or required pretreatments at −3 °C to enable them to germinate at 12 °C. They required from 10 to 30 days to germinate in our experiments. They germinated by two, but occasionally one, three, and even four, germ tubes growing through pores in the relatively thick inner wall at each end of the slit after its enlargement. Cultures grew at 0 °C with an optimum at 12–15 °C, and a maximum between 18 and 21 °C.

scholarly journals Impact of temperature on Bacillus cereus spore germination in ultra-high temperature chocolate milk

Food Research ◽  
2019 ◽  
pp. 808-813
Author(s):  
Ubong A. ◽  
C.Y. New ◽  
L.C. Chai ◽  
Nur Fatihah A. ◽  
Nur Hasria K. ◽  
...  
Keyword(s):  
High Temperature ◽  
Bacillus Cereus ◽  
Incubation Time ◽  
Spore Germination ◽  
Infection Risk ◽  
Effect Of Temperature ◽  
Harsh Environment ◽  
Chocolate Milk ◽  
Data Gap ◽  
Germination And Growth

Bacillus cereus spores are capable of surviving the harsh environment and more often, they cause great concern to the dairy industry. The current research was conducted to study the effect of temperature on germination and growth of B. cereus spores in UHT chocolate milk; the study was carried out at 8°C, 25°C and 35°C over a span of seven days. The results showed that no growth was observed at 8°C. At 25°C, a rapid increase in growth was observed as early as Day 1, from an initial count of ten spores to 4.01 log10 CFU/mL. Meanwhile, at 35°C, the growth on Day 1 was more rapid in which the count promptly increased to 8.07 log10 CFU/mL. Analysis of graph trend showed that the number of vegetative cells decreased while the number of spores increased with incubation time due to nutrients exhaustion. This study fills up the data gap towards understanding the possible issues that might arise in the actual scenario and at the same time, suggests a suitable approach to minimize infection risk caused by B. cereus spores.

Corrigenda - Measurement of the total water potential of aqueous solutions of polyethylene glycol - A comparison between osmometer, thermocouple psychrometer and equilibrated soil cores

Soil Research ◽  
1993 ◽  
Vol 31 (1) ◽  
pp. 1
Author(s):  
IM Wood ◽  
IK Dart ◽  
HB So
Keyword(s):  
Polyethylene Glycol ◽  
Water Potential ◽  
Close Correlation ◽  
Ease Of Use ◽  
Effect Of Temperature ◽  
Soil Cores ◽  
Total Water ◽  
Matric Potential ◽  
Thermocouple Psychrometer ◽  
Water Potentials

This study examined two polyethylene glycol (PEG) polymers (PEG 6000 and PEG 10000) and compared measurements of water potential obtained with a thermocouple osmometer and thermocouple psychrometers at three temperatures (15, 25 and 35�C) and five osmdalities (50, 100, 200, 300 and 400 g/1000 g water). These were then compared with estimates of matric potential of three soils brought to equilibrium with PEG solutions of the same osmolalities. At the same osmolality and temperature the two PEG polymers gave essentially the same water potential. There was a significant effect of temperature on water potential which corresponded closely with changes in specific gravity of the PEG solution. There was a close correlation between the measurements of water potential of the PEG solutions obtained with the osmometer and the psychrometers (R = 0.99). However, the psychrometer gave increasingly lower values than the osmometer as water potential decreased. The differences in the measurements between the two methods are thought to be the result of design and calibration differences. The ease of use of the osmometer is such that it is recommended for routine use. The water potentials of the soil cores brought to equilibrium with the PEG 10 000 solution were linearly related to the water potentials of the PEG solutions estimated from both the osmometer and psychrometers (R2 = 0.84). However, there were clear deviations from a 1:l relationship. It was concluded that the results from the soil cores could not be used to determine which of the two instruments gave the more accurate measurement of water potential of PEG solutions.

Ascospore germination, growth in culture, and imperfect spore formation in Cookeina sulcipes and Phillipsia crispata

1975 ◽  
Vol 53 (1) ◽  
pp. 56-61 ◽  
Author(s):  
J. W. Paden
Keyword(s):  
Germ Tube ◽  
Outer Wall ◽  
Wall Layer ◽  
Spore Formation ◽  
Spore Surface ◽  
No Formation ◽  
Ascospore Germination ◽  
Germ Tubes

Ascospores of Cookeina sulcipes germinate by one of two modes: (1) by the production of blastoconidia on sympodially proliferating conidiogenous cells which may arise from any point on the spore surface, and (2) by a thick polar germ tube. No ascospores were seen to germinate both ways. The conidiogenous cells are occasionally modified into narrow hyphae. The blastoconidia germinate readily but are evidently very short-lived. Ascospores of Phillipsia crispata germinate by two polar germ tubes; there is no formation of blastoconidia. In both species the inner ascospore wall separated from an outer wall layer during germination. In culture both C. sulcipes and P. crispata form arthroconidia. The arthroconidia are uninucleate; they germinate readily and reproduce the species when transferred to fresh plates.

scholarly journals Effect of Temperature and Water Potential on Survival and Mycelial Growth of Phaeomoniella chlamydospora and Phaeoacremonium spp.

Plant Disease ◽  
2001 ◽  
Vol 85 (2) ◽  
pp. 195-201 ◽  
Author(s):  
E. C. Whiting ◽  
A. Khan ◽  
W. D. Gubler
Keyword(s):  
Water Treatment ◽  
Water Potential ◽  
Growth Rates ◽  
Mycelial Growth ◽  
Hot Water ◽  
Effect Of Temperature ◽  
Effective Control ◽  
Conidial Suspension ◽  
Hot Water Treatment ◽  
Phaeomoniella Chlamydospora

Phaeomoniella chlamydospora, a species of Phaeomoniella, and two species of Phaeoacremonium, P. inflatipes and P. aleophilum, have been associated with young grapevine decline in major production regions of California. Phaeomoniella chlamydospora has been isolated from healthy vines and inoculated but non-symptomatic vines and rooted cuttings. Effects of temperature and water potential on fungal response in culture were investigated to find effective control strategies for nurseries. Mycelial growth rates at temperatures 5 to 37°C showed a quadratic response with optimum growth rates for Phaeomoniella chlamydospora and P. aleophilum at 25°C and at 30°C for P. inflatipes. Response to water potential varied by isolates within a species, but isolates of Phaeomoniella chlamydospora were not sensitive to decreasing water potential. A conidial suspension and plugs of agar with mycelia were placed in glass vials and incubated in hot water for 15 to 120 min. Conidia were sensitive to hot-water treatment after 15 and 30 min. Nevertheless, mycelia of P. inflatipes from agar plugs grew on potato dextrose agar at 22°C after 120 min incubation at 51°C. Because the fungi were not killed by incubation in glass vials at 51°C, methods other than hot-water treatment may be more effective in eliminating Phaeomoniella chlamydospora and Phaeoacremonium spp. from dormant vine cuttings.

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