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MANUAL OF DETERMINATIVE BACTERIOLOGY 



Genus IV. Nanus Holmes, 

 {hoc. cil., 123.) 

 Viruses of the Dwarf-Disease Group, inducing diseases characterized by dwarfing 

 of host plants or by growth of adventitious shoots with short internodes; chlorotic 

 mottling absent. Generic name from Latin nanus, dwarf. 

 The type species is Nanus loganobacci Holmes. 



Key to the species of genus Nanus. 

 I. Infecting rosaceous plants. 



A. In loganberry and Phenomenal berry. 



1. Nanus loganobacci. 



B. In black raspberry. 



C. In peach. 



D. In ocean spray. 



E. In strawberry. 



F. In prune and plum. 



II. Infecting graminaceous plants. 

 A. In sugar cane. 



1. Nanus loganobacci Holmes. 

 (Handb. Phytopath. Viruses, 1939, 124.) 



From New Latin loganobaccus, specific 

 epithet of loganberry, Riibus loganobaccus 

 Bailey. 



Common name: Loganberry -dwarf 

 virus. 



Hosts: ROSACEAE—Rubus logano- 

 baccus Bailey, loganberry and Phenom- 

 enal berry. 



Geographical distribution: United 

 States (Oregon, Washington, and Cali- 

 fornia). 



Induced disease : In Phenomenal berry, 

 leaves small, obovate, rigid, new canes 

 short, spindly. In young plants, some 

 necrosis along and between veins, leaves 

 crinkled, finer veins chlorotic. Stems 

 not streaked or mottled, normal in color. 

 In late stages, canes very short, inter- 

 nodes short. Sepals and petals of flowers 

 small. Fruit of fair size, but druplets 

 ripen unevenly and tend to fall apart 

 when picked. Loganberry is less sus- 

 ceptible than the Phenomenal berry but 

 is similarly affected. 



2. Nanus orientalis. 



3. Nanus mirabilis. 



4. Nanus holodisci. 



5. Nanus fragariae. 



6. Namis cupitliformans. 



7. Nanus prrinil 



8. Nanus sacchari. 



Transmission : By aphid, Capitophorus 

 tetrahodus (APHIDIDAE). Not by 

 inoculation of expressed juice. 



Literature: Zeller, Phytopath., 15, 

 1925, 732 (Abst.) ; 17, 1927, 629-648. 



2. Nanus orientalis H. {loc. cit., 124). 

 From Latin orientalis, eastern. 



Common names : Raspberry -streak vi- 

 rus, raspberr}'^ eastern blue-stem virus, 

 raspberry rosette virus. 



Host: ROSACEAE—Rubus occiden- 

 talis L., black raspberry. 



Insusceptible species : ROSACEAE — 

 Rubus idaeus L., red raspberry; R. pho- 

 enicolasius Maxim., Japanese wineberry. 



Geographical distribution : United 

 States. 



Induced disease : In black raspberry, 

 plants stunted, becoming smaller in suc- 

 cessive seasons; leaves usually curled, 

 close together on canes, dark green, often 

 twisted so as to be upside down. New 

 canes show bluish violet dots, spots, 

 or stripes near their bases and sometimes 

 also on branches or on fruiting spurs. 



