Conditions for Infection of Apple by Phytophthora syringae

• Published in: Journal of phytopathology 2003-04, Vol.151 (4), p.190-194
• Main Authors: Harris, D. C., Xu, X.-M.
• Format: Article
• Language: English
• Subjects: apple; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; oospore germination; Phytopathology. Animal pests. Plant and forest protection; Phytophthora syringae; Systematics. Morphology. Development cycle. Physiology; zoospore infection
• ISSN: 0931-1785; 1439-0434
• DOI: 10.1046/j.1439-0434.2003.00704.x

The processes leading to Phytophthora fruit rot were divided into two main stages for the purposes of investigating the effects of temperature and duration of wet periods on pathogen development: oospore germination and infection of fruit by zoospores. It was found that the first stage was markedly affected by temperature over the range 10–20°C and required a wet period of 4–7 days. At 18 and 20°C, activation was low regardless of the length of the wet period. Once oospore germination (first stage) had occurred, free water was necessary for only a few hours for fruit infection (second stage) to occur, but the incidence of infection rose rapidly over the first 48 h, regardless of temperature over the range 10–20°C. From the data obtained, mathematical models were produced relating the incidence of Phytophthora fruit rot to the two weather variables. These models can be used to develop a weather‐based risk assessment system for the disease.