The Latent Period of Eastern Filbert Blight Jeff Stone, Ken Johnson, John Pinkerton, Jay W. Pscheidt The time it takes from a spore infecting a hazelnut shoot to the time we begin to see a canker symptom is called the latent period. This latent period is very long for EFB and is generally considered to be 15 months. However, it can be much longer before we see symptoms. The experiment described below outlines the problem. A total of 30, healthy 2-year old hazelnut trees were placed at five sites within a diseased orchard in the spring of 1988. These trees were replaced with 30 more healthy trees each week. After one week of exposure, trees were taken to a clean holding site for several months to allow symptoms to develop. A total of 120 trees were exposed during that spring. A total of 63 trees or 30% became infected and showed typical EFB cankers in June of 1989. These trees were destroyed before spores could infect the other trees. The remaining trees were held an additional year at this clean holding area. A total of 16 more trees developed typical EFB cankers in June of 1990, about 26 months after exposure. This means it may take up to three growing seasons (two years) after infection before symptoms of EFB are seen. There is one other requirement before cankers form. An extended cold period, during which the tree undergoes dormancy, is necessary to initiate formation of stromata.				Life Cycle Tour Previous / Next / Animated   Although you do not see symptoms, the fungus is growing within the cambium and primary phloem. Mycelium of the fungus is stained blue in this picture.
	For more information contact OSU Faculty. More sites related to Hazelnuts Disclaimer				Life Cycle Tour Previous / Next / Animated Management Location Life Cycle Risk Assessment References Home