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Calif, The Growth of Citrus and Other Crors as Affected by 

 Minor Elements , To (l) develop methods of sufficient 

 sensitivity for detection and estimation of Co, Cr, Ni, V, 

 etc.; (2) investigate requirements of citrus and other crops 

 for these and other elements and determine symptoms in 

 deficiences; (3) study toxic effects of various elements on 

 crops; (/t) study methods of application for essential minor 

 elements and effects of treatment upon yield, growth, etc., 

 of plants; and (5) study effects of variation in supply of 

 minor elements upon absorption of major essential elements. 

 Soils & PI. Nutr. 1025 



Calif. The Citrus Fsorosis Diseases , (l) Obtain further knowledge 

 of different types of psorosis, their economic importance and 

 control or prevention, and the nature and properties of their 

 causal viruses; (2) investigate virus strains and interactions 

 between virus strains; (3) at cellular level, study initiation 

 and development of virus-induced bark lesions on psorosis- 

 infected citrus trees. 

 PI. Path. 1082 



Calif. Patholorf.c a l Investigations; Transmission. Symptoms tology. 

 Host Range, Histology. Prevention or Control and Other Studies 

 of the So-Called Orange Tree Quick Decline (Tristeza) DiseasT^ 

 and its Causal Virus , Maintain studies on causal virus; (1) 

 purification and isolation, electron microscopy, thermal 

 properties, possible inactivation of virus in host by heat 

 treatment, mechanical transmission; (2) host range' v/ithin citras 

 family, symptomless hosts, hosts other than citrus; (3) 

 susceptibility of citrus seedlings and "tolerant" scion- 

 stock combinations to stem-pitting phase of disease; (Z*) anatomical 

 effects of virus on infected trees, anatomy of stem pitting, 

 effects of different strains of virus; (5) virus strains, degrees 

 of virulence, cross-protection between strains, "seedli/ig yellows" 

 and its relation to quick decline; (6) combined infections of 

 quick decline and psorosis viruses; (?) cooperate with State 

 Department of Agriculture in learning distribution of disease and 

 establishing quarantine boundaries. Use mild strains of virus 

 as a control. 



PI. Path, 1376 



