© 1998 Kluwer Academic Publishers. Printed in the Netherlands. 23 In vitro tolerance and resistance to burrowing nematode, Radopholus similis, in Anthurium species

scherzerianum Schott, and one species of breeding interest, were screened in vitro for tolerance and resistance to the nematode Radopholus similis Cobb, 1893. Adjustment of the tolerance measurement to the initial and uninoc-ulated treatment measurement improved the screening method. Use of a nematode strain with a relatively slow reproduction rate enabled concurrent screening for tolerance and resistance to R. similis in Anthurium. Based on a lower relative symptom index, A. pittieri Engl., A. ravenii Croat and Baker, A. antioquiense Engl. and A. aripoense N. E. Br. reduce nematode damage as compared to the reference standard, ‘Midori’. However, A. antioquiense and A. aripoense had higher root damage than ‘Midori’. Lower nematode damage in A. pittieri and A. ravenii is positively correlated with greater plant vigor or to fewer target roots for nematode infection. A. ravenii was among the most resistant species as measured by nematode reproduction. This is followed by A. aripoense and A. pittieri. Thus, strong plant vigor, fewer target roots for nematode infection, and/or lower nematode reproduction (higher nematode resistance) resulted in lower nematode damage in A. pittieri and A. ravenii. Combining the nematode damage and nematode reproduction results, A. pittieri and A. ravenii were identified as more tolerant than the reference standard ‘Midori’