. ( Van Laere et al., 2007 ), Prunus spp. ( Kukharchyk and Kastrickaya, 2006 ; Liu et al., 2007 ), Rhododendron spp. ( Eeckhaut et al., 2007 ), and Rosa spp. ( Gudin, 1993 ). Liu et al. (2007) described a technique used to rescue young embryos of
 al. 2022 ). Two of these subspecies have been reported in North America and are associated with disease in Prunus spp., X. fastidiosa ssp. fastidiosa , and X. fastidiosa ssp. multiplex . A third subspecies was described in the southwestern United
Prunus serotina is a wild, fast-growing tree native to North America ( Marquis, 1990 ) which has been widely planted in European forests and has spread from plantations to invade several types of woodlands and open habitats on poor soils ( Muys
‘Greenpac’ is a new peach hybrid rootstock [ Prunus persica (L.) Batsch × P. davidiana (L.) Batsch] × [ P. dulcis (Mill.) D.A.Webb × P. persica ] developed by Agromillora Iberia, S.L., Barcelona, Spain, for use mainly as a rootstock for peach
Ten genetically diverse peach [Prunus persica (L.) Batsch] seedling rootstocks were studied for 10 years on Fox sand using `Redhaven' as the scion. The purpose of the experiment was to assess the performance of three Harrow Research Station (Ont.) hybrid selections (H7338013, H7338016, and H7338019) and two northern China introductions (`Chui Lum Tao' and `Tzim Pee Tao') against five commercial standards, two of which were selected in Canada (`Harrow Blood' and `Siberian C') and three in the United States (`Bailey', `Halford', and `Lovell'). Rootstock performance was assessed indirectly by measuring or subjectively rating various aspects of scion performance including annual trunk cross-sectional area (TCA); final tree height, spread, and TCA; bloom and fruit set intensity; yield and yield efficiency; canker (Leucostoma spp.) severity; defoliation rate; winter injury; cold hardiness of flower buds and shoot xylem; and tree survival. Rootstock effects on the above measurements and ratings were significant in some years and not in others. Year effects were always large and significant, while rootstock × year interactions were usually small and not significant. In the combined analyses over years, the largest rootstock effects were obtained for bloom, fruit set, and defoliation ratings and for TCA measurements. Three cumulative responses, including marketable yields, yield efficiency, and tree survival, were used for comparing the five experimental rootstocks with the five commercial standards and also for ranking the 10 rootstocks with respect to each other to assess their potential commercial value as peach rootstocks. `Chui Lum Tao', H7338013, and `Bailey' had the most commercial potential for southern Ontario because they typically promoted above average cumulative yield, yield efficiency, and tree survival. `Tzim Pee Tao', `Siberian C', and `Harrow Blood' were less valuable, with low cumulative marketable yields. `Halford' and `Lovell' were the least valuable, with the lowest tree survival (17%). Performance of H7338013 exceeded that of both parents (`Bailey' and `Siberian C'), H7338019 exceeded `Siberian C' but not `Bailey', while performance of H7338016 was inferior to both parents. Wider testing of the experimental rootstocks on different soil types and climatic zones is needed.
Consecutive replanting of peach (Prunus persica) trees on the same orchard site can result in various replant problems and diseases, including armillaria root disease (Armillaria spp.), which develops upon contact between the roots of newly planted trees and infested residual root pieces in the soil. There is little information regarding the quantity of roots remaining in stone fruit orchards following tree removal and land clearing. We investigated the utility of ground-penetrating radar (GPR) to characterize reflector signals from peach root fragments in a controlled burial experiment and to quantify the amount of residual roots remaining after typical commercial orchard clearing. In the former experiment, roots ranging from 2.5 to 8.2 cm in diameter and buried at depths of 11 to 114 cm produced characteristic parabolic reflector signals in radar profiles. Image analysis of high-amplitude reflector area indicated significant linear relationships between signal strength (mean pixel intensity) and root diameter (r = -0.517; P = 0.0097; n = 24) or the combined effects of root diameter and burial depth, expressed though a depth × diameter term (r = -0.630; P = 0.0010; n = 24). In a peach orchard in which trees and roots had been removed following typical commercial practice (i.e., trees were pushed over, burned, and tree rows subsoiled), a GPR survey of six 4 × 8-m plots revealed that the majority of reflector signals indicative of root fragments were located in the upper 30 to 40 cm of soil. Based on ground-truth excavation of selected sites within plots, reflectors showing a strong parabolic curvature in the radar profiles corresponded to residual root fragments with 100% accuracy, whereas those displaying a high amplitude area represented roots in 86.1% of the cases. By contrast, reflectors with both poor curvature and low amplitude yielded roots for less than 10% of the excavated sites, whereas randomly selected sites lacking reflector signals were devoid of any roots or other subsurface objects. A high level of variability in the number of residual roots was inferred from the radar profiles of the six plots, indicating an aggregated distribution of root fragments throughout the field. The data further indicated that at least one residual root fragment would be present per cubic meter of soil, and that many of these fragments have diameters corresponding to good to excellent inoculum potential for armillaria root disease. Further GPR surveys involving different levels of land clearing, combined with long-term monitoring of armillaria root disease incidence in replanted trees, will be necessary to ascertain the disease threat posed by the levels of residual root biomass observed in this study.
will continue to be essential for sustaining efficient, profitable cultivation of Prunus spp. ( Gradziel, 2009 ; Moreno, 2004 ; Reighard et al., 1989 ). In California and other regions where Prunus species have been cultivated through many
. Esmenjaud, D. 2006 The Ma gene from Myrobalan plum ( Prunus cerasifera Ehr.) conferring a complete-spectrum resistance to rootknot nematodes ( Meloidogyne spp.) is a member of a TIR-NBS LRR gene cluster 28th Symp. European Soc. Nematol Blagoevgrad
quadrangularis L.), apricot ( Prunus armeniaca L.), low-chill peach ( Prunus persica [L.] Batch.), aonla ( Emblica officinalis Gaertn), ber or Chinese date (Z iziphus xylopyrus Willd. or Ziziphus jujuba Mill.). The vegetable section features two chapters
)], jujube [ Ziziphus jujuba ( Ma et al., 2012 )], almond [ Prunus dulcis ( Dangl et al., 2009 )], and sweet cherry [ Prunus avium ( Lacis et al., 2009 )]. SSR markers were developed previously in peach and used for genetic diversity assessment ( Li et al