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Overwintering Of Erwinia Amylovora Inside Living Host Tissue In Cache Valley, Utah, G. Doyle Morrill

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Experiments were conducted to see if Erwinia amylovora (Burrill) Winslow et al. overwinters inside living host tissue in Utah. Bacteria, collected from apple, pear, mountain ash, chokecherry and Pyracantha, were used in the experiment. Isolates taken from buds and inner bark plated on nutrient yeast dextrose agar, we re tested by serological and bacteriophage techniques. Those showing positive tests were then inoculated into Bartlett pear seedlings to test virulence.

Both virulent and avirulent isolates were isolated from each species of plant in the experiment. Pathogenic bacteria were isolated from diseased tissue near cankers, as well as from apparently healthy inner …

An Experimental Study Of Variation Within And Between Populations Of Petrophytum Caespitosum (Nutt.) Rydb. With Emphasis On Numerical Techniques, Frank R. Drysdale

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Nine populations of sixty-eight individuals representing the distribution of Petrophytum caespitosum (Nutt.) Rydb. (Rosaceae) in the Intermountain Region were investigated for taxonomically significant variation using numerical techniques. On the basis of 19 morphological characters 3 subspecific taxa are recognized. Two taxa are existing subspecies: P. caespitosum (Nutt.) Rydb. var. caespitosum and P. caespitosum (Nutt.) Rydb. var. elatius (S. Wats.) Tides. One new subspecies is described: P. caespitosum (Nutt.) Rydb. var. latifolium. The ecology of the species is discussed. The floral and vegetative anatomy are described. Chromosome counts of 3 populations have given n = 9. A list of herbarium …