Effect of Rootknot Nematode On Tomato Rootstocks in Non-Fumigated Open Field Production

Soil fumigation has been an essential component of open field fresh market tomato production systems since the 1960’s.  Farming without fumigants has remained a challenge, in part because the management of many soilborne diseases has been achieved with conventional genetics.  Building new plant systems using rootstocks grafted to market acceptable varieties is a common practice in protected agriculture but has not gained acceptance in open field production.  The performance of tomato rootstocks in open field conditions (Pineda fine sand) under the care of a commercial grower was evaluated in a replicated field trial.  A raised bed, plastic mulched production system with drip irrigation and fertigation was employed by the grower.  The experimental site was located in St. Lucie County, FL.  The experimental design consisted of 6 blocks with 10 treatments consisting of 2 scions (‘Biltmore ‘and ‘FL-47’) grafted on 3 rootstocks (‘Aloha’, ‘Multifort’ and ‘H-7997’- 50 plants per treatment block) in a randomized design.  Controls consisted of ungrafted and self-grafted scions.  Plant vigor as judged by overall plant growth as measured by plant height was significantly different for ‘Biltmore’ on ‘Multifort’ and ungrafted ‘FL-47’ then that of ‘FL-47’ on ‘H-7997’.  The severity of root galling from Meloidogyne spp. was greatest on self grafted and non grafted ‘FL-47.  ‘Biltmore’ grafted onto ‘Multifort’ and ‘Aloha’ and FL-47 grafted onto ‘Aloha’ had no apparent root galling, indicating that damage from Meloidogyne spp was minimal on those rootstock/scion combinations.  Nematode egg counts within root systems were greatest on the ungrafted ‘Biltmore’.  However, egg masses were not found when ‘Biltmore’ was grafted onto ‘Multifort’ and ‘Aloha’ rootstocks.  No root galling was observed when FL-47 was grafted onto ‘Aloha’.