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Environmental factors impact temporal Passalora sequoiae conidia counts from Leyland cypress
Author(s) -
WilliamsWoodward Jean L.,
Copes Warren E.
Publication year - 2017
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/jph.12590
Subject(s) - conidium , cypress , biology , pinaceae , growing season , vapour pressure deficit , blight , horticulture , fungicide , botany , atmospheric sciences , pinus <genus> , physics , photosynthesis , transpiration
Needle blight disease, caused by Passalora sequoiae , results in a progressive loss of leaf tissue on Leyland cypress (× Cupressocyparis leylandii ) within container and field tree nurseries, in the landscape and on Christmas tree farms. Fungicide schedules have been developed in response to seasonal symptom progression and conidia dispersion without clarification of the influence of weather conditions on disease. Conidia count data of P. sequoiae were collected approximately weekly from June to December in 2001 in Watkinsville, GA , and in 2002 in Dearing, GA . Peak conidia numbers were trapped in September and October. Daily weather data summaries were obtained from a weather station at each location. Deterministic models were developed individually for summer (1 June to 30 September) and fall (1 October to 21 December) seasons. A three‐day moving average ( MA ) of average daily temperature (avgT) had a positive quadratic relationship with conidia counts in the summer season. A 10‐day MA of avgT, vapour pressure deficit ( VPD ) and total solar radiation (SolR) had a positive quadratic, a negative linear and positive linear relationship, respectively, with conidia counts in the fall season. The models show that the seasonal shift to cooler fall temperatures, along with lower VPD and SolR, favour production and dispersal of P. sequoiae conidia.