A method for determining density of suspensions of urediniospores of Melampsora larici-populina causing leaf rust of poplar

TLDR: Urediniospores of leaf rust of poplar were harvested from the leaves of a variety ofpoplar clones grown in the field and suspended in distilled water and serially diluted to calculate spore production per unit leaf area as a parameter of disease intensity.

Abstract: Urediniospores of leaf rust of poplar ( Melampsora larici-populina Kleb.) were harvested from the leaves of a variety of poplar clones grown in the field. These spores were suspended in distilled water and serially diluted. For optical densities 0.006 ⩾ x ⩽ 0.332 the number of spores per ml ( x ) (from haemocytometer counts), was linearly related to the optical density ( y ) determined at 640 nm, by the formula y = 2.411 e -03 + 8.548 e -07 x ( R = 0.998; P Populus x euramericana clones. The use of this technique for calculating spore production per unit leaf area as a parameter of disease intensity is discussed.