|Reighard, G - CLEMSON UNIVERSITY|
|Ouellette, D - CLEMSON UNIVERSITY|
|Brock, K - CLEMSON UNIVERSITY|
|Newall, W - CLEMSON UNIVERSITY|
Submitted to: Acta Horticulturae
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 11, 2002
Publication Date: October 31, 2004
Citation: Reighard, G.L., Ouellette, D.R., Beckman, T.G., Brock, K.H., Newall, W.C. 2004. Field-testing peach rootstock selections for tolerance to peach tree short life and replant sites in south carolina. Acta Horticulturae. 658:429-434. Interpretive Summary: Guardian peach rootstock is currently utilized commercially as a bulked seed lot collected from a small number of F1 siblings. To date it has performed well on peach tree short life sites (PTSL), providing superior tolerance to PTSL compared to Lovell, the previous commercial standard. There are notable differences in nursery performance and physical characteristics of the various F1 seedlings lines currently mixed into the bulk Guardian seed lot, some of which are undesirable. The purpose of this trial was to determine the relative tolerance of wider range of Fl Guardian siblings to PTSL. After two growing seasons some differences in vigor, suckering and early orchard establishment were evident. Most Guardian selections grew as or more vigorously than Lovell. However, a small number suckered more than Lovell. Many Guardian selections displayed better planting survival than Lovell. It is too early in these trials to look at differences in PTSL survival. Long term this trial may lead to the identification of Guardian selections with PTSL resistance, nursery and orchard characteristics superior to that of the current bulked mix.
Technical Abstract: Peach tree short life (PTSL), a bacterial canker/cold injury disease syndrome of peach, remains a replant problem in warm temperate regions of the United States, A bulked seed line trademarked Guardian Brand BY520-9 has performed well (i.e., survival) when compared to Lovell rootstock, the industry standard, in field trials in South Carolina. However, undesirable nursery characteristics and some segregation of phenotypic traits in the bulked F1 seedling population have made it necessary to re-evaluate mother parents for future seed production. Only a few of the F1 seedling populations were tested in earlier plantings. The objective was to evaluate untested with previously tested Guardian Brand BY520-9 selections and Lovell rootstock (e.g., standard) at grower locations in South Carolina to determine their short life tolerance and orchard productivity on replant orchard sites. F1 seedling lines from 36 selected Guardian parents budded with RubyPrince and AutumnPrince were planted in the winter of 1999-2000 on replant sites at five grower farms in South Carolina. After two growing seasons, there were some significant differences in tree survival and growth. F1 seedlings from Guardian selections were as or more vigorous than Lovell at four of the five sites. There were significant differences in tree growth among sites as well as significant genotype x site interactions. One selection (2-11-1) was within the top eight rootstocks for trunk cross-sectional growth at all sites. Among rootstocks planted at all sites, trees on Lovell were generally smaller. Most tree death after two years was due to drought, machinery, animals or theft. Lovell had one of the lowest survival rates (89%) across all sites. PTSL was not observed, but generally appears at three to five years of age. Trees on Guardian Brand BY520-9 rootstocks grew and survived as well or better than Lovell rootstock after two years in the field. Extensive field-testing will ultimately lead to selection of parental genotypes that produce superior F1 peach rootstock seedlings for use on South Carolina replant sites.