VIEW ARTICLE

Ecology and Epidemiology

Effect of Leaf Maturity and Shoot Age of Clones of Populus species on Susceptibility to Melampsora larici-populina. J. K. Sharma, Visiting fellow, Department of Forestry, Australian National University, P.O. Box 4, Canberra, A.C.T. 2600, Australia, Present address: Division of Forest Pathology, Kerala Forest Research Institute, Peechi-680653, Kerala, India; W. A. Heather(2), and P. Winer(3). (2)Reader, Department of Forestry, Australian National University, P.O. Box 4, Canberra, A.C.T. 2600, Australia; (3)Senior lecturer, Department of Statistics, Australian National University, P.O. Box 4, Canberra, A.C.T. 2600, Australia. Phytopathology 70:548-554. Accepted for publication 15 November 1979. Copyright 1980 The American Phytopathological Society. DOI: 10.1094/Phyto-70-548.

Leaves of varying maturity were detached from 4- to 33-day-old shoots of clones of Populus nigra ‘Semi-evergreen’ (field susceptible) and P. × euramericana ‘65/27’ (field resistant) grown in a rust-free glasshouse. The detached leaves were inoculated with uniform loads of uredospores of Melampsora larici-populina, and incubated in a controlled environment. Reaction type of the leaves and latent period (LP) for flecks and for uredia production were recorded. Within a shoot, LP and reaction type were related to leaf maturity, but for leaves of the same maturity, selected from shoots of varying age, the reaction type was determined by age of shoot. In comparisons between the clones or between leaves of different maturities or zones of shoot within clones, higher susceptibility was associated with shorter latent period (LP). The ecological and epidemiological significance of the results are discussed.