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Mich. Virus Diseases Affecting Peach and Maintenance of Vitrus- 



Free Standard Peach Varietes , (1) Develop methods and materials 

 for indexing; (2) learn presence or absence of and identitiy 

 of latent viruses in peach; (3) host range of peach viruses 

 and symptom expression in different hosts; (4) separation and 

 identification of virus entities present in peach in North 

 Central region and learn ability to incite disease singly 

 and in combination; (5) economic importance of several 

 diseases; (6) variability within viruses; (?) experimental 

 transmission of viruses; (8) influence of environment on 

 development and severity of diseases; (9) morphological, 

 physiological and biochemical aspects of disease development; 

 (lO) chemical, and other methods of freeing plants and plant 

 parts from virus infection and lessening injurious effects of 

 viruses; (l) obtain and preserve elite sources of scions and 

 rootstecks indexing as virus-free to be increased for 

 experimental work and for commercial propagation of certified 

 nursery stocks, 



Pl.Path.% & Bot. 820 (NC-IA) 



Minn, Stone Fruit Virus Diseases and. Their Control . To (l) 



learn occurrence, distribution, severity and identification 

 of viruses of hardy species of Prunus and hybrid varieties 

 grown in Northern Great Plains; (2) learn effect of viruses 

 on growth and yield of stone fruits; (3) study host range 

 of viinises of Prunus; (4) study effect of environmental 

 factors on expression of symptoms; (5) learn method of trans- 

 mission and dissemination of viruses of hardv Prunus, 

 especially in relation to insect vectors; (6) develop methods 

 and materials for indexing viruses; and (?) learn resistance 

 or tolerance of Prunus species and varieties to viruses 

 present or that might affect hardy species, 

 PI. Path. & Bot. 2223 (NC-l^) 



Mo. Stone Fruit Virus Diseases and Their Control . To (l) 



investigate new and different approaches to the problem of 

 virus disease control including: continuation and extension 

 of the indexing program; (2) fundamental studies of virus 

 infection; (3) pvirification studies; and (4) chemotherapeutic 

 studies. 



Hort. 68 (NC-14) 



Mo. Bacterial Spot, Brown Bot and Peach Scab Control and 



the Effect of Some of the Newer P'esticides Upon Fruit Finish 

 of Peaches . To test promising synthetic organic fvmgicides 

 as orchard sprays for effectiveness against brown rot, their 

 phytotoxic effects and their value in control of peach scab; 

 evaluating antibiotics which from in vitro tests have been 

 found to be highly toxic to Xanthanomas pruni, for control 

 of bacterial spot, and noting post harvest developnent of 

 rots with different orchard fungicide programs. 



Hort. 243 



