Rapid Method of Rating Forest Trees for General Resistance to Foliar Pathogens

Author： Stelzer H. E. Polk R. B. Loegering W. Q.

Publisher： Society of American Foresters

ISSN： 0015-749X

Source： Forest Science, Vol.29, Iss.2, 1983-06, pp. : 215-221

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Abstract

A simple and rapid method of rating forest trees for general resistance to foliar pathogens was tested. Rapidity of taking and recording data is especially important where many individuals must be scored at frequent intervals and where the amount of disease on that individual plant may change quickly with time, as was the case in this investigation. The system directly compares, over time, the relative amount of disease on a single plant with all other plants in this test. The Pinus ponderosa Laws : Scirrhia acicola (Dearn.) Siggers association (brown-spot needle blight of ponderosa pine) was used in evaluating the rating method. Results, based on one judge's evaluation during one disease cycle, indicate that the method is repeatable over location. Furthermore, measurement of general resistance to brown-spot of individual ponderosa pine trees is possible regardless of the amount of disease. The time that it took to take notes on a plantation using this method was only a fraction of what would have been required if the evaluations had been made using conventional note-taking methods. With experience, one can rate individual plants, with the aid of a tape recorder, while walking through the plantation at a comfortable pace. This method makes the evaluation of large numbers of trees feasible in terms of time and cost. Forest Sci. 29:215-221.