scispace - formally typeset
Search or ask a question

Showing papers by "Jyoti Kumar Sharma published in 1979"


Journal ArticleDOI
TL;DR: 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.

5 citations


Journal ArticleDOI
TL;DR: Advantages of employing urediniospores produced per unit area as a measure of relative susceptibility in horizontally resistant clones and in tracing disease progress are discussed.
Abstract: Field infection of Melampsora leaf rusts ( M. larici-populina Kleb. and M. medusae Thum.) in five poplar clones ( Populus × euramericana ‘I-154’, ‘I-214’, ‘I-455’, P. regenerata and P. nigra cv. ‘Semi-evergreen’) was assessed using three disease parameters, namely, uredinia per mm 2 , urediniospores per mm 2 , and urediniospores produced per uredinium. All parameters demonstrated differential susceptibility in the clones tested and the relative susceptibility of the clones was the same when the two former parameters were used for assessment. However, urediniospores produced per mm 2 showed a few significant differences from conventional assessment based on uredinial numbers. Additionally more urediniospores were produced per uredinium on leaves of P. × euramericana cv. ‘I-154’,, than in ‘I-214’, and ‘I-455’, although ‘I-154’, was rated more resistant by other parameters. Advantages of employing urediniospores produced per unit area as a measure of relative susceptibility in horizontally resistant clones and in tracing disease progress are discussed.

5 citations