A hydroponic method was developed and tested for screening red raspberry genotypes for resistance to Phytophthora fragariae var. rubi, the most common causal agent of Phytophthora root rot in raspberry. Plants of `Titan' and `Encore' exhibited typical disease symptoms, with the latter developing significantly smaller stem lesions and fewer petiole lesions. The resistant cultivar, `Latham', regenerated healthy root tissue from the crown and older-order roots after initial infection and necrosis of young roots and exhibited no other symptoms beyond minor leaf chlorosis. This component of the resistance reaction has not been documented previously. A segregating F1 population from the cross of `Latham' × `Titan' had a survival rate of 56% with 42% classified as resistant, exhibited minimal symptoms, and produced varying amounts of healthy root tissue. This screening method allows multiple observations of all plant tissues, including roots, under repeatable and definable growth chamber conditions. It should be useful for classifying the phenotype of individuals in segregating red raspberry populations to investigate the inheritance of Phytophthora root rot resistance using molecular markers.
J.A. Pattison, W.F. Wilcox, and C.A. Weber
Gina E. Fernandez and Marvin P. Pritts
A 2-year study was conducted to investigate the influence of the light environment on source-sink relationships in `Titan' red raspberry. Treatments imposed included flower and cane removal in conjunction with partial or whole canopy shading. Raspberry plants were remarkably resistant to a reduction in carbon supply. Yields and primocane production were maintained even when canopies were shaded. Furthermore, if raspberry plants were prevented from producing a full crop in one year, yields the following year tended to be higher than normal. These data, and other studies demonstrating that raspberry roots are strong carbon sinks, suggest that raspberry plants may rely on stored carbohydrate to mature the current crop of fruits when current photosynthate is inadequate. This trait is characteristic of some perennial species adapted to progressively changing environments, but may not be optimal for horticultural situations where growing conditions are relatively constant from year to year. A large root storage capacity and excessive primocane production likely contribute to the relatively low yields that are typical of this species.
Jean-Pierre Privé and N. Allain
Four primocane fruiting (PP) red raspberry cultivars, `Bogong', `Cascade', `Heritage', and `Dinkum', were grown in exposed or sheltered (50% permeable artificial windbreak) sites fully exposed to prevailing westerly winds. The cultivars were evaluated to determine the effects of wind stress on vegetative and reproductive development and leaf gas exchange during the establishment year. The artificial windbreak resulted in an overall 35% reduction in wind velocity, increased the number of calm days (<5.4 km·h–1) and decreased the incidence of strong breezes (>36 km·h–1). Concurrently, the artificial windbreak did not have much of an effect on altering relative humidity, air or soil temperature. All cultivars responded similarly to wind exposure Plants in exposed sites had reduced leaf areas, internode lengths, leaf, cane, and total above ground dry weights. Leaf gas exchange parameters (Pn, gs and Ci) expressed per unit leaf area did nor differ between treatments for most of the season but the sheltered plants as a whole supported a greater total leaf area and must have fixed a greater amount of carbon than the exposed plants. These larger sheltered plants produced a more extensive fruiting framework and resulted in a 2-fold yield increase. For these reasons, it is highly recommended to shelter raspberry plants from wind in the establishment year.
Doina Clapa, Alexandru Fira, and Nirmal Joshee
’ ( Prunus cerasus × Prunus canescens ) is a dwarf cherry rootstock. Rubus idaeus , Rubus fruticosus , Vaccinium macrocarpon , and Vaccinium corymbosum as well as ‘Tayberry’ ( Rubus fruticosus × Rubus idaeus ) are important fruit shrubs. Lycium
Saki Toshima, Marika Fujii, Momoko Hidaka, Soya Nakagawa, Tomonari Hirano, and Hisato Kunitak
Rubus (Rosaceae) comprises more than 740 species with additional commercially cultivated raspberry ( R. idaeus ssp. idaeus) and blackberry ( R. fruticosus ) ( Gu et al., 1990 ). The fruit are used as ingredients in fresh dishes and processed
Inga A. Zasada and Patrick P. Moore
Plant–parasitic nematodes were first reported in Rubus species in North America in the 1930s, when Pratylenchus species were associated with declining red raspberries ( Rubus idaeus L.) ( McElroy, 1992 ). Of the plant–parasitic nematodes
Mary Woodhead, Ailsa Weir, Kay Smith, Susan McCallum, Katrin MacKenzie, and Julie Graham
the Scottish Crop Research Institute Rubus idaeus EST database where a match was found or the similarity between the amplified Rubus and Prunus sequences are shown. The primer sequences designed to amplify the loci for identification of
Archana Khadgi and Courtney A. Weber
prickled samples, the surfaces of prickle-free samples were covered with only simple, nonglandular trichomes in all the species observed. Fig. 1. Gross morphology of Rubus idaeus L. (red raspberry) ‘Caroline’ and ‘Joan J’ showing ( A ) prickled and ( B
Nina R.F. Castillo, Barbara M. Reed, Julie Graham, Felicidad Fernández-Fernández, and Nahla Victor Bassil
Most of the cultivated fruit species in Rubus belong to two subgenera: Idaeobatus (raspberry) and Rubus (formerly Eubatus ) (blackberry). Idaeobatus contains european red raspberry ( R . idaeus ), north american red raspberry ( R
Primocane-fruiting raspberries ( Rubus idaeus L.) produce new canes (primocanes) from buds on the roots or from basal buds on older canes or the crown. Flowers are initiated on these primocanes regardless of daylength and when field-grown can