. Baldwin for technical support, K. McRae for assistance with statistical analysis, and J. Wilson for the original selection of the rootstock survivors. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal
C.G. Embree, B.H. Lesser and A.D. Crowe
M. Carmen González-Mas, M. José Llosa, Antonio Quijano and M. Angeles Forner-Giner
, citrus-growing success depends on availability of suitable rootstock that is tolerant of low Fe. Trifoliate orange [ Poncirus trifoliata (L.) Raf.], sweet orange [ C. sinensis (L.) Osb.], and Carrizo citrange ( C. sinensis × P. trifoliata ) are all
Judy A. Thies, Jennifer J. Ariss, Richard L. Hassell, Sharon Buckner and Amnon Levi
been lost from the U.S. market because of human health risks and groundwater contamination ( Chitwood, 2003 ). Thus, there is increased interest in the development of alternative technologies such as use of resistant rootstocks for grafting to manage
Eduard Alcañiz, Jorge Pinochet, Carolina Fernández, Daniel Esmenjaud and Antonio Felipe
Fourteen Prunus rootstocks were evaluated against mixtures of several isolates of the root-lesion nematode Pratylenchus vulnus Allen and Jensen in three greenhouse experiments. Most of the tested rootstocks are new releases or materials in advanced stages of selection that also have incorporated root-knot nematode resistance. The plums Torinel (Prunusdomestica L.) and Redglow (P. salicina Lindl. P. munsoniana Wight and Hedrick cv. Jewel) showed a moderately resistant response; their final nematode population levels were lower or slightly higher than inoculation levels. Low nematode reproduction also was found in the peach–almond hybrid G N No 22 [P. persica (L.) Batsch P. dulcis (Mill.) D.A. Webb] and the plum Bruce (P. salicina P. angustifolia Marsh.), and although these rootstocks did not perform as well as Torinel and Redglow, they also appear to be poor hosts for P. vulnus.
Paula B. Aguirre, Yahya K. Al-Hinai, Teryl R. Roper and Armand R. Krueger
Nitrogen (N) uptake was compared on 10 dwarf apple rootstocks (M.9 EMLA, M.26 EMLA, M.27 EMLA, M.9 RN29, Pajam 1, Pajam 2, B.9, Mark, B.469, and M.9 T337) grafted with the same scion (`Gala') in a four year-old orchard. Trees were treated in either Spring or Fall 1998 with 40 g of soil applied actual N per tree using ammonium nitrate enriched to 1% 15N. Both percentage of N (%N) and N from fertilizer (NFF) in leaf tissue were highly affected by the rootstock and the season of N application. Generally, higher %N and NFF were observed for spring than fall applications, except for leaves collected during early June 1998. Generally, M.26 EMLA, M.27 EMLA, and M.9 RN29 were the most efficient rootstocks in N uptake for spring applied nitrogen. M.9 EMLA was most efficient late in the season following fall application. Mark was more efficient early in the season for fall applied N than spring application. However, trees on Mark rootstock had the lowest %N throughout the season regardless of the time of N application. Pajam 1 and Pajam 2 were the least efficient rootstocks in N uptake following fall N application. Rootstock also significantly affected %N and NFF of wood tissue. Generally, trees on B.469 had the highest %N in their wood regardless of the season of application. No single rootstock had consistently higher N from fertilizer in their wood tissue after spring application. At the May 1999 sampling date, M.26 EMLA had higher NFF than M.27 EMLA, Pajam 1, Pajam 2, and B.9 with a fall application. Other rootstocks were intermediate. Samples collected in August showed that Pajam 1 was the least efficient rootstock in N uptake for fall applied N compared to other rootstocks, except for Pajam 2 and B.9 that were intermediate. Leaf and wood tissue analysis showed that different rootstocks had different N uptake efficiencies throughout the season. Generally, M.26 EMLA, M.27 EMLA, M.9 RN29 and M.9 EMLA were more efficient at N uptake regardless the season of N application. Pajam 1 and Pajam 2 were the least efficient.
B.H. Lesser, C.G. Embree and A.D. Crowe
The precocity and productivity of 30 Kentville Stock Clone (KSC) apple (Malus domestica Borkh.) rootstocks, with `McIntosh' and `Delicious' as scion cultivars, were assessed independently of each other using a procedure involving computer-aided fitting of curves to yearly production data. A good fit to the data was obtained after biennial fluctuations in yield were removed by using a weighted, 3-year running average. For all 30 rootstocks combined, `McIntosh' was more precocious and reached a higher level of productivity compared to `Delicious'. There was poor correlation between precocity and productivity.
Carolina Fernández, Jorge Pinochet, Daniel Esmenjaud, George Salesses and Antonio Felipe
New Prunus rootstocks and selections were evaluated for their reaction to Meloidogyne arenaria (Neal) Chitwood, M. incognita (Kofoid & White Chitwood), or M. javanica (Treub) Chitwood. Most of the clones were peach-almond hybrids (P-AHs) [P. persica (L.) Batsch × P. dulcis (Mill.) D.A. Webb] or plums of Spanish and French origin. In a first experiment, the P-AH Hansen 2-168 and plums GF-31 (P. cerasifera Ehr.) and GF 8-1 (P. cerasifera × P. munsoniana Weigth et Hedr.) were highly resistant to the mixture of five isolates of M. javanica. The P-AHs Barrier and Titan × Nemared were resistant and moderately resistant, respectively; GF-677, MB 3-13, MB 2-2, and MB 2-6 were susceptible. In the second and third experiment, the plums P 1079, P 2175, the hybrids Afgano (P. dasycarpa Ehrh.), G × N No 22, and G × N No 15, both P-AHs, and Nemared peach were highly resistant to mixtures of five isolates of M. incognita or M. arenaria. The plums P 2980 (P. cerasifera) and GF 8-1 tested against either root-knot species were also highly resistant. Cachirulo × (G × N No 9), a P-AH, showed less resistance to M. arenaria than to M. incognita. Montclar (P. persica) and the P-AHs Torrents AC and GF-677 were susceptible to both species.
1 Grape rootstock breeder and geneticist.
Terence L. Robinson and William C. Johnson
79 WORKSHOP 10 (Abstr. 667–668) Tree Fruit Rootstocks: Current Materials and Future Trends
Wesley R. Autio
168 ORAL SESSION 44 (Abstr. 312-318) Tree Fruits: Rootstocks