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Abstract Detail



Ecology/Pathology

Jiang, Qianwei [1], Kirk, William.W [2], Hanson, Linda.E [1].

Short term elevated temperature exposure impacts growth of mycelium of Cercospora beticola.

Cercospora leaf spot (CLS), caused by the fungus Cercospora beticola, is the most serious foliar disease in sugarbeet growing regions worldwide. Several models based on meteorological threshold parameters are available to help growers predict developmental events in epidemics of Cercospora leaf spot. Environmental factors such as temperature, relative humidity, and leaf wetness are integrated into the model to predict when conditions are conducive for conidial production, conidial germination, and infection. Daily severity values (DSV) are accumulated daily until thresholds are reached, indicating fungicide applications need to be made. However, DSV continue to accumulate even when air temperatures are above the optimum range reported for development and growth of C. beticola. This information prompted an enquiry into the impact of different durations of temperature in excess of 90oF (32.2oC) on developmental and growth responses of C. beticola. A set of experiments (in vitro) were initiated to determine the effects of different durations of thermal exposure from 28 to 40°C. Isolates were incubated at 28°C for 48 hours before testing. The initial growth before differential temperature exposures were imposed on cultures was recorded.  Individual sample plates were randomly assigned to one of the temperature treatments, 28, 34, 36, 38 and 40°C for 4, 6, or 8h and then incubated at 28°C. Colony diameters were measured including at 24, 36 and 48 h after initiation of exposure to the different temperatures. The diameter of the initial growth was subtracted from these values to give the growth during and after different temperature exposures. The results indicated that temperatures in excess of 94oF (34.4oC) inhibited C. beticola mycelial growth after 4-8 h exposure.  Isolates of C. beticola varied in response to variation in duration of exposure at different temperatures.  The results show that Cercospora beticola growth can be inhibited by elevated temperatures during exposure times similar to what may be encountered in beet production regions.


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1 - Michigan State University, Plant and Soil Sciences Building 1066 Bogue St., Room 494, East Lansing, MI, 48824, USA
2 - Michigan State University, Plant Biology Laboratories 578 Wilson, Rm. B35 , East Lansing, MI, 48824, USA

Keywords:
short term elevated temperature
cercospora beticola
Hyphal Growth
disease forecasting model development.

Presentation Type: Offered Paper - Paper
Session: 7
Location: Auditorium/Kellogg Hotel and Conference Center
Date: Tuesday, June 10th, 2014
Time: 9:00 AM
Number: 7003
Abstract ID:124
Candidate for Awards:Graduate Student Oral Presentation Award


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