selling or planting of certain Ribes species or cultivars, particularly the nonnative European black currant, R . nigrum , that has been found to be extremely susceptible to WPBR ( Barney and Hummer, 2005 ; McKay, 2000 ). One source of immunity to C
Todd A. Burnes, Robert A. Blanchette, Jason A. Smith, and James J. Luby
Eric T. Wolske, Bruce E. Branham, and Kevin J. Wolz
leaf area and decreasing leaf thickness. As the level of shading increased, plant yield decreased, and the authors concluded that shade levels should be no more than 60% for blueberries to remain economically viable. Black currants ( Ribes nigrum ) have
Doina Clapa, Alexandru Fira, and Nirmal Joshee
method was tested for: Rubus idaeus ‘Willamette’, Lyc ium barbarum , Amelanchier canadensis ‘Rainbow Pillar’, Ribes nigrum ‘Tisel’, cherry rootstock ‘Gisela 5’ ( Prunus cerasus × P. canescens ), Drosera capillaris , Drosera rotundifolia , and
The search for appropriate white pine blister rust (WPBR) (Cronartium ribicola J.C. Fischer) resistant germplasm to use in black currant (Ribes nigrum L.) breeding programs began in 1935 in Ottawa. Crosses were made in 1938 and 1939 with three different Ribes L. species and two standard black currant cultivars. The resulting seedlings from these crosses were evaluated for rust resistance. Three promising selections resulted from this program and were named `Coronet', `Crusader' and `Consort'.
Stanislaw Pluta and Agata Broniarek-Niemiec
Field resistance to white pine blister rust (WPBR) (Cronartium ribicola J. C. Fischer) was investigated on 53 black currant (Ribes nigrum L.) genotypes (cultivars and breeding selections) in 1998 and 1999. Uredia did not form on the black currant `Titania' and 17 advanced selections during field evaluations made at the Experimental Orchard at Dabrowice, near Skierniewice, Poland.
In North America for many years the commonly held solution to white pine blister rust (Cronartium ribicola J.C. Fischer) (WPBR) was to eradicate all currants and gooseberries (Ribes L.). That approach was tried to no avail. Can currants and gooseberries be successfully grown in North America? You bet they can! Vast areas of the United States and Canada are ideal for Ribes production. Black currants (Ribes nigrum L.) are a processed fruit and production may compare to that of grain. Many of the areas that presently grow other berries could easily grow Ribes. The main barriers for production in North America are state restrictions and the availability of up-to-date information and data for growers, processors, legislators and the consuming public. I suggest that this conference and the people herein form that task group and initiate the cooperative dialogue and set forth a process to approach the WPBR problem in a holistic manner.
Kim E. Hummer, Joseph D. Postman, John Carter, and Stuart C. Gordon
During Dec. 1997 and Jan. 1998, the gooseberry mite, Cecidophyopsis grossulariae Collinge, was observed to infest 48 currant and gooseberry (Ribes L.) cultivars in a field plantation in Corvallis, Ore. The mite was observed on 29 black currant, (Ribes nigrum L.), two red currant [Ribes rubrum L. and R. sativum (Rchbch.) Syme], 12 gooseberry [R. uvacrispa L., R. oxyacanthoides var. setosum (Lindley) Sinnot], and three R. ×nidigrolaria Bauer cultivars and the hybrid R. nigrum × R. pauciflorum Turcz. ex Pojark. A range of mite infestation levels was observed, with some cultivars not being infested, some with light infestation, having 1 to 100 adult mites per bud, and some heavily infested, with more than 100 mites per bud. On lightly infested buds, the mites were inside bud and leaf scales; in heavily infested buds, mites were also observed on floral primordia. Scales of infested buds were often loose and appeared more open than noninfested ones. Mite distribution varied by branch within a plant. Black currant cultivars with the heaviest infestation of C. grossulariae were of Scandinavian, Russian, Scottish, and Canadian origin. The Russian black currant cultivar Tunnaja was the most heavily infested with more than 1000 mites per bud. Floral primordia were damaged in heavily infested buds.
Black currant (Ribes nigrum L.) plants of eight varieties were grown either through black plastic mulch or in bare soil and with the area between the rows cultivated or sodded with red fescue (Festuca rubra L.). Over 6 years, black plastic mulch increased yields by 26% over no mulch and cultivation between the rows increased yield by 32% compared to sod. The effect of both treatments was additive, cultivation and black plastic increased yield by 68% over grass and no black plastic. Growers are recommended to plant black currants through black plastic and avoid using sod between the rows.
Paul J. Zambino
Artificially inoculated single-leaf cuttings and small plants consistently differentiated european black currant (Ribes nigrum L.) cultivars susceptible to white pine blister rust (WPBR; Cronartium ribicola J.C. Fisch.) from immune cultivars carrying the Cr resistance gene. Black currant cultivars Consort, Crusader, and Titania showed no signs of infection with any of 21 strains of WPBR, suggesting that strains able to overcome immunity conferred by the Cr resistance gene, if they exist, are uncommon in North America. However, in red currant (Ribes rubrum L.), two sources of material presumed to represent the immune cultivar Viking showed no resistance to infection. All rust strains infected and sporulated as if the cultivar were fully susceptible, casting doubt on the true identity of available sources of `Viking'.
D.R. Bergdahl and H.B. Teillon
White pine blister rust (WPBR) (Cronartium ribicola J. C. Fischer) has been present in Vermont and other northeastern states since the early 1900s. The fungus is commonly observed on currants and gooseberries (Ribes L.) every year, but incidence varies on eastern white pine (Pinus strobus L.). Our general impression has been that Vermont has had a relatively low level of infection on eastern white pines; however, we recently found rust incidence in Christmas tree plantings in northern Vermont to range from 10 to 42% (average 20%) based on 721 trees surveyed. Also, in pole-sized stands in southern Vermont, incidence ranged from 12 to 46% (average 32%) and 76% of these trees had main stem infections. In the southern survey, 98% of wild ribes plants had varied amounts of both urediniospores and teliospores. These preliminary survey data suggest that incidence of WPBR may be more significant than previously thought and therefore, additional survey work is needed. We screened cultivars of Ribes for susceptibility to WPBR. Eighteen cultivars were inoculated in the field with a mass collection of aeciospores of C. ribicola. The percentages of leaf area infected ranged from 0 to 49 for the urediniospore stage and from 0 to 55 for teliospores. The gooseberry (Ribes uva-crispa L.) `Welcome' had the highest percentage of leaf area with urediniospores, while black currants (R. nigrum L.) `Coronet,' `Consort,' and `Crusader' had no visible infection. Presently, Vermont has no WPBR regulations. However, previous federal laws did restrict black currant cultivation. Little is known about the genetic diversity of WPBR or its potential for change. Caution must be used when considering any cultivation of Ribes for the purpose of producing fruit because our valued white pine resources could be negatively impacted.