Managing Difficult Plant Diseases: Inoculation, infection, and symptoms separated in time

Sycamore anthracnose occurs only on sycamores and London plane trees and is favoured by infections during cool, wet weather as new leaves emerge in spring. Photo courtesy James Chatfield

By James Chatfield, Joseph Boggs, and Erik Draper

The inoculum that arrives at the plant via wind, splashing rain, or a vector cannot be seen. Then, a spore germinates and penetrates into plant tissue, a nematode inserts its stylus into the plant, or a vector inserts the pathogen into plant tissue, and the pathogen is still not seen. It spreads through the plant and establishes a host-parasite relationship with plant cells.

Turf professionals have no idea the pathogen is there until symptoms develop on the plant (e.g. leaf blighting and discolouration along the veins of a sycamore due to an infection from the sycamore anthracnose pathogen). Symptoms can develop days, weeks, or sometimes even months or years after inoculation, penetration, and infection. Green industry professionals are effectively in the dark all that time. Among other things, this makes effective timing and use of disease-controlling pesticides such as fungicides difficult. Symptom development and damage to the plant may be inevitable even when the infected plant looks fine.

Read the full article: Managing Difficult Plant Diseases

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