A virus was isolated from carrots and purified utilizing chloroform, differential ultracentrifugation, polyethylene glycol precipitation, and rate-zonal sucrose density-gradient centrifugation.  Flexuous rod-shaped particles with a modal length of 736 nm were found in purified preparations.  The virus was transmitted by aphids (Myzus persicae and Cavariella aegopodii) given 5- to 10-minute acquisition and transmission feeding periods.  Properties in crude sap included: longevity in vitro = 2 days, thermal inactivation point = 50–55 C, and dilution end point = greater than 10^–5.

The virus was named carrot thin-leaf virus (CTLV).  Virus morphology, vector relationships, and properties in crude sap suggest that CTLV belongs to the potyvirus group.  Differences in host range, symptomatology, and serology distinguish CTLV from other members of the potyvirus group.

Additional key words: umbelliferous virus.