|Reighard, Greg - CLEMSON UNIV.|
Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 9, 2005
Publication Date: July 1, 2006
Citation: Nyczepir, A.P., Beckman, T.G., Reighard, G.L. 2006. Field evaluation of Guardian peach rootstock to different root-knot nematode species. Acta Horticulturae. 713:303-309. Interpretive Summary: Root-knot nematodes are an important pest of peach in the U.S. and other parts of the world. Four major Meloidogyne spp. have been reported to cause damage to stone fruits throughout the world, but Meloidogyne incognita and M. javanica are the predominant species found on peach and plum. In previous short-term greenhouse studies, commercial sources of Guardian peach rootstock were effective in suppressing the reproduction of M. incognita and M. javanica 110 days after inoculation. However, additional long-term research is needed to elucidate the effect different root-knot nematode species have on growth parameters of Guardian and other advanced Prunus germplasm. Two separate field microplot studies were initiated to examine the susceptibility of two advance lines of Guardian rootstock (SC 3-17-7 & SL 2891) to M. incognita, M. javanica, and/or M. floridensis. Results indicate that tree growth suppression of SC 3-17-7 was greater in the presence of M. javanica as compared to M. incognita and the uninoculated plots, whereas SL 2981 growth was not affected by either nematode. In the other microplot study, M. floridensis and M. incognita did not suppress tree growth SC 3-17-7, Nemaguard, or Flordaguard rootstocks as compared to the uninoculated control These data provide useful insights into the potential recommendation of Guardian rootstock in peach orchards infested with certain root-knot nematode species. Since M. incognita is the predominant species on peach in the Southeast and not M. javanica, our findings indicate that both Guardian lines would perform better in M. incognita infested soil than the previous standard Lovell rootstock. Additionally, these data illustrate that SC 3-17-7, Nemaguard, and Flordaguard are all resistant/tolerant to M. floridensis.
Technical Abstract: Advance lines of Guardian (i.e., SL 2891 and SC 3-17-7) and Lovell peach rootstocks were evaluated for their susceptibility and growth response to Meloidogyne incognita (GA-peach isolate) and M. javanica (NC-tobacco isolate) 23 months after inoculation in field microplots. Results indicate that there was a significant interaction between nematode and rootstock for above-ground tree growth. Growth suppression, as measured by trunk diameter and fresh shoot weight of Guardian line SC 3-17-7 was greater (P < 0.05) in the presence of M. javanica as compared to M. incognita and the uninoculated plots. Guardian line SL 2981 growth was not affected by either nematode when compared to the uninoculated plots. Tree growth of Lovell was suppressed by both M. incognita and M. javanica when compared to the uninoculated plots. Below-ground growth suppression, as measured by dry root weight, was greater in Lovell than either SC 3-17-7 or SL 2891 regardless of nematode species. No difference in dry root weight was detected between the two Guardian lines. Root galling occurred on all rootstocks tested with either M. incognita or M. javanica. Root galling was more abundant on Lovell, intermediate on SL 2891 and least abundant on SC-3-7-17. Similar results were also detected for number of eggs per gram dry root weight regardless of nematode species. In another microplot study, M. floridensis and M. incognita did not suppress tree growth SC 3-17-7, Nemaguard, or Flordaguard rootstocks as compared to the uninoculated control. Meloidogyne floridensis reproduced on all 3 rootstocks, with greatest number of eggs per gram dry root being produced on Guardian and Nemaguard.