. Canadian journal of agricultural science. Agricultural Institute of Canada; Agriculture. Figure 2. The condition of the roots of four varieties of beans differing in their to the dry rot organism. The process of producing disease resistant types by " hybridization is necessarily slow because of the length of time that is required to isolate and fix the desired type from the miseellanecus population that will appear as the result of crossing. This diversity of the residting population, while it constitutes a hindrance to rapid pro- gress, is one of the factors in favor of th
. Canadian journal of agricultural science. Agricultural Institute of Canada; Agriculture. Figure 2. The condition of the roots of four varieties of beans differing in their to the dry rot organism. The process of producing disease resistant types by " hybridization is necessarily slow because of the length of time that is required to isolate and fix the desired type from the miseellanecus population that will appear as the result of crossing. This diversity of the residting population, while it constitutes a hindrance to rapid pro- gress, is one of the factors in favor of the liybridization method of plant improvement in tliat the diverse popu- lation obtained affords a good opportunity of isolating a plant possessing the maximum of desirable qualities. A few examples will suffice to illustrate the work that is being done, mainly by our plant pathologists, in the production of resistant strains by tlie isolation of re- sistant individuals from commercial varieties. Blinn (9) by selection within commercial varieties was able to isolate a cantaloupe resLstant to rust. Hansen (10) has secured by .selection a type of sand cherry re- sistant to mildew. Shamel and Cobey (11) obtained a strain of tobacco resistant to wilt by one year's selection. Bain et al. (12) selected a strain of Red Clover apparently resistant to anthraenose. Nor- ton (13) found that the tomato varieties Stone and Stirling Castle possessed considerable resist- ance to the causal organism of leaf mold. Jones (14) developed a strain of cabbage possessing resistance to yellows. Barrus () rejiorts a sti'ain of beans, ob- tained by a grower from an individual plant selection, which is resistant to both strains of the bean anthraenose fungus. The possibilities of the slower and more difficult method of securing disease resistant plants by means of hybridization, wjll be dealt with somewhat more fully. Ill this connection the work done in securing beans re- sistant to the causal organis
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