Authors
H. E.
Waterworth
,
Plant Pathologist
, and
Ray
Mock
,
Support Scientist, USDA, ARS, Plant Quarantine Office, Bldg. 580, Beltsville, MD 20705
ABSTRACT
Nested polymerase chain reaction (PCR) assays were evaluated for use on a routine basis in a quarantine program to detect phytoplasmas in dormant fruit tree scionwood collected during the winter season. Phytoplasmas associated with peach yellow leaf roll, Western X, apricot chlorotic leaf roll, plum leptonecrosis, and apple proliferation diseases were detected in all known infected sources. Phytoplasmas in Prunus spp. were readily detected in both dormant bud and internodal tissues. Use of nested PCR versus a single primer pair resulted in electrophoresed PCR products that were easier to interpret. The nested PCR procedure has replaced 3-year tests with grafts on sensitive indicators to detect this group of pathogens.