These experiments have proved conclusively the effect of cedar rust on the normal processes of the apple leaf. The diseased leaves use more oxygen and give off more carbon dioxide than the healthy leaves, and at the same time less starch and sugar is made than in the healthy leaves. When transpiration is reduced, the food supply - the soluble plant food - is accordingly reduced. The difficulty of diseased trees not being able to get sufficient food through insufficient transportation, by water, may be overcome by either of two methods - (1) irrigation or (2) fertilization, with neutral or slightly acid fertilizers, manure being an excellent material to use. The first and most important method of cedar rust control is to cut the cedars for a distance of at least a half mile from the orchard. Second in importance is by timely sprayings, and third, is by feeding the trees. In order that cedar rust control is to be realized, cooperation in a community is essential. “Team work" is necessary in all lines of work and the orchardist should not forget this fact. / Master of Science