Host Status of Ornamental Shade Trees and Shrubs to Plant Parasitic Nematodes.

Oregon leads the United States in nursery production of shade trees and is third in deciduous and broadleaf evergreen shrub production. Plant-parasitic nematodes have been implicated in problems with the growth of plants in nurseries and are also of phytosanitary risk. A greenhouse experiment was conducted to evaluate the host status of four trees () and two shrubs , ) to , and . Each plant/nematode treatment was replicated five times, and the experiment was conducted twice. Plants were inoculated with 3,000 eggs of or and 2,500 individuals of two weeks after planting. After three months, the plants were harvested, and the total density of nematodes in soil and roots for and the total density of second-stage juveniles (J2) in soil and eggs on roots for and were determined. The final nematode population (Pf) and reproductive factor (RF = Pf/initial population density) were calculated. For and , all of the ornamental trees and shrubs would be considered as fair to good hosts with RF values > 1. had the highest Pf (5,234 total J2 and eggs/pot) and RF value (28.4) on . For , all of the ornamental trees and shrubs were fair to good hosts, except for . was not a host for with an RF value of almost 0. This is the first report of , and as hosts for , and . This is also the first report of and as hosts for and the non-host status of for .