- 65 - 



111. Stone Fruit Virus Diseases and Their Control; Illinois . 



To (l) purify and characterize peach X-disease virtis and 

 cherry necrotic ring-spot virus j (2) diagnose stone fruit 

 virus diseases by serological, physical, or chemical methods; 

 (3) learn insect vectors of peach X-disease virus; (k) ascertain 

 rate of spread of cherry necrotic ring-spot virus under orchard 

 conditions and evaluate effect of ring-spot disease on fruit 

 quality and yield on tree growth; and, (5) detect presence 

 and learn severity of stone fruit virus diseases in nurseries 

 or orchards and their environs, 



Hort., Plant Path, 68-372 (NC-l^t. See Part 1?, Section c) 



Mich, Virus Diseases Affecting Peach and Maintenance of Virus - 

 Free Standard Pestch Varieties ^ To (1) develop methods and 

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

 identity of latent vinises in peach; (3) host range of peach 

 viruses and symptom expression in different hosts; (k) separa- 

 tion and identification of virus entities present in i)ea<!h in 

 north central region and learn ability to incite disease 

 singly and in combination; (5) economic importance of several 

 diseases; (6) variability within viruses; (7) experimental 

 transmission of viruses; (8) influence of environment on devel- 

 oiment and severity of diseases; (9) morphological, physio- 

 logical and biochemical aspects of disease developnoent; (lO) 

 chemical, and other methods of freeing plants and plant parts 

 from virus infection and lessening injurious effects of viruses; 

 and, (11) obtain and preserve elite sources of scions and root- 

 stocks indexed as virus -free to be increased for experimental 

 work and for commercial propagation of certified nursery stocks. 

 Plant Path,& Bot, 820 (NC-li^• See Part 17, Section c) 



Minn, Stone Fruit Virus Diseases and Their Control , To (1) 



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 virtises on growth 

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

 Prunus ; (h) study effect of environmental factors on expression 

 of symptoms; (5) learn method of transmission and dissemination 

 of viruses of hardy Prunus , especially in relation to insect 

 vectors; (6) develop methods and materials for indexing viruses; 

 and, (7) learn resistance or tolerance of Prunus species and 

 varieties to viruses present or that mis^"t affect hardy species. 



Plant Path. 86 Bot,, Hort, 2223 (NC-l^^, See Part 17, 



Section c) 



