|Reighard, Greg - CLEMSON UNIV., SC|
Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Proceedings
Publication Acceptance Date: November 4, 1996
Publication Date: N/A
Interpretive Summary: A peach seedling rootstock, BY520-9 (Guardian), was identified in an unbudded trial in 1991 as providing greater tree survival than Lovell (standard rootstock) on peach tree short life (PTSL) sites. Preliminary greenhouse reports also indicate that Guardian rootstock has some resistance to root-knot nematode. Grower demand has resulted in commercial availability of Guardian before all root-knot nematode testing was completed. In 1995-96, studies were initiated to determine the susceptibility of Guardian rootstock to two root-knot nematode species, Meloidogyne incognita and M. javanica. Results indicate that commercial seed sources of Guardian peach are poor hosts to the populations of M. incognita and M. javanica tested. Reproduction by both nematode species was less on Guardian plants as compared to Lovell. These data provide useful insights into the host suitability of Guardian rootstock to two root-knot nematode species. Additionally, Guardian rootstock is showing promise as an alternative to preplant fumigation with methyl bromide for control of M. incognita, M. javanica and PTSL induced by the ring nematode (Criconemella xenoplax).
Technical Abstract: Currently, the USDA-Byron & Clemson Univ. are providing commercial nurseries with "bulk" seed of BY520-9 (Guardian) selections from seed orchards of surviving seedlings from the mother tree which was lost. An unanswered question about the commercially available Guardian seed is its host suitability toward root-knot nematodes, specifically M. incognita & M. javanica. In 1995-96, studies were initiated to determine the susceptibility of Guardian rootstock to M. incognita and M. javanica. Ten-day-old Guardian-USDA, Guardian-Clemson and Lovell peach seedlings were transplanted into 10-cm-diam. pots containing 450 cm3 sand/vermiculite. Approx. 4,000 eggs of M. incognita or M. javanica were added to each pot five days later. Uninoculated seedlings served as controls. The experiment was terminated after 110 days. Root penetration & development of M. incognita into Guardian-USDA & Lovell seedlings were also studied. Results indicate that both Guardian-USDA and Guardian-Clemson commercial seed sources are poor hosts to the populations of M. incognita & M. javanica tested. Reproduction by M. incognita & M. javanica, as indicated by no. of eggs & no. of eggs per egg mass, was less on plants from both Guardian sources as compared to Lovell. However, gall formation was detected on roots of plants from both Guardian sources, & for M. incognita there were just as many galls produced as on Lovell. Root gall formation by M. javanica was less abundant on the Guardian sources as compared to Lovell. Root penetration studies indicate that M. incognita J2/s penetrate Guardian roots, root galls form, but the majority of the nematodes do not complete their life cycle.