Open AccessEffect of Microclimate on Leveillula taurica Powdery Mildew of Sweet Pepper
Author(s) -
Y. Elad,
Yoel Messika,
Michal Brand,
Dalia Rav David,
A. Sztejnberg
Publication year - 2007
Publication title -
phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.264
H-Index - 131
eISSN - 1943-7684
pISSN - 0031-949X
DOI - 10.1094/phyto-97-7-0813
Subject(s) - microclimate , powdery mildew , pepper , horticulture , biology , germination , greenhouse , relative humidity , daytime , agronomy , botany , ecology , physics , thermodynamics , atmospheric sciences , geology
Sweet pepper-Leveillula taurica microclimate relations were studied under controlled conditions and in commercial greenhouses. Conidial germination occurred at 10 to 37°C and was optimal at 20°C. Conidial viability declined as temperatures increased to 40°C for 6 h. Leaf colonization was optimal at 15 to 25°C. Severe leaf infections occurred at 15 to 20°C and conidiation was suppressed at 20 to 25°C. Highest germination rates were observed at 75 to 85% relative humidity (RH). Severity of leaf coverage by symptoms was high for plants which were subjected to longer periods of temperatures between 10 to 15°C and daytime RH between 85 to 95%, and positively correlated with nighttime RH. Disease severity was negatively correlated with lengthy periods of temperatures >25°C, day and night average temperatures, and average daytime RH. Conversely, leaf shedding was relatively high under conditions characterized by long periods of temperatures >20°C and <13°C, and positively correlated with average daytime temperatures and periods of RH <75%. Increasing nighttime temperatures by heating and daytime temperatures by closing the greenhouse side walls reduced disease in two commercial greenhouse experiments. A midseason shift from a cooler greenhouse climate to warm daytime climate halted epidemic development. Flower number and yield were reduced in infected crops.