•^ 16 - 



Stone Fruits 



Calif, Factors Influencing the Re-Establishment of Peach 



Orchards on Old Peach Soils . To discover and devise merfchods 

 for preventing the peach replant growth depression. 

 Pomol. 1126 



Calif. Separation of Individual Viruses from Complexes Latent 

 in Many Stone Fruit Varieties and Rootstocks ^ To (1) obtain 

 pure cultures of ringspot, sour cherry yellows, and prune 

 dwarf viruses; (2) determine effects of separate viruses and 

 effects of various combinations of these viruses on stone fruit 

 trees; and (3) maintain pure cultures of viruses for other 

 research in this and other States. 

 PI. Path. 1584 (W-22) Coop. ARS 



Calif. The Canker Complex of Stone Fruit Trees - Etiology, Envi- 

 ronmental Relations and Control . (1) Learn if canker disease 

 of stone fruits is caused by a single bacterial species or by 

 several closely related species and if fungus species sometimes 

 associated with canker symptoms are of primary or secondary 

 importance; (2) importance of certain physiological factors 

 induced by microorganisms associated with canker in occurrence 

 of disease in its various phases; (3) study effect of soil 

 type, nutrition, soil moisture, soil temperature, nematode and 

 soil micro-organisms, and possible soil. toxins on development 

 of canker phase of diseases; (A) learn nutritional needs of 

 microorganisms associated with different phases of canker 

 complex; (5) time and method of natural infection by bacteria 

 commonly associated with disease and the environmental con- 

 ditions favoring infection; (6) from above, formulate an 

 effective control program for disease or diseases on various 

 stone fruit hosts. 

 PI. Path. 171A 



Colo. Diseases of Fruit Trees . To (l) investigate virus diseases 

 of stone fruits, especially peach mosaic and Western X; (2) 

 investigate distribution and severity, nature of infection, and 

 spread, and possible control of Cytospora guinnosis of peach; and 

 (3) provide an adequate fungicide testing program for control of 

 fire blight, powdery mildew, Coryneum blight, Cytospora gummosis 

 of peach. 



Bot. 79 



Colo. The Characterization of Strains of Peach Mosaic Virus and 

 Changes Associated With the Host-Cell Metabolism of Infected 

 Plants . Tb (1) isolate abnormal proteins associated with plants 

 infected with different strains of peach mosaic virus; (2) 

 characterize the strains of the isolated virus and try to establish 

 their infectivity; (3) determine changes in host-cell metabolism 

 and try to correlate changes with different strains of the virus. 

 Bot., PI. Path. 235 (W-22) 



