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Pierluigi (Enrico) Bonello, The Ohio State University, Department of Plant Pathology; James T. Blodgett, Daniel A. Herms, |
In recent experiments, trees were first inoculated in the lower stems. Later inoculation higher on the stem resulted in smaller lesions on trees that were inoculated at the base with S. sapinea compared with trees that were not inoculated at the base (i.e., the controls). This study confirmed that SIR occurs in this pine species as well as in Monterey pine (Bonello, Gordon, and Storer, 2001).
We also have preliminary data that show systemic accumulation in the induced trees, described previously, of chemicals active in resistance in pine trees, which further proves that we are measuring resistance and not some other unknown phenomenon (Blodgett and Bonello, 2001).
Lastly, we have recently found that fertilization of red pine trees with an N-P-K fertilizer in controlled field experiments significantly increased the severity of Sphaeropsis tip blight. Thus, higher host vigor (evident from superior growth rates of fertilized trees) appeared to increase disease susceptibility in this pine. These studies will be replicated with Austrian pine.