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.
Brian W. Geils
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'.
White pine blister rust (Cronartium ribicola J.C. Fisch.) (WPBR) was discovered on Ribes L. in New York in 1906, although it was accidentally introduced from Europe on pine (Pinus L.) seedlings. The spread of this destructive fungus has changed the forests in North America. After decades of reduced planting because of the concern over the impact of WPBR, white pine (Pinus strobus L.) is now being restored in the lake states of Minnesota, Wisconsin and Michigan. Although the potential for growing white pine is high on many sites, the disappearance of a seed source because of logging and fires means that reestablishment of white pine to these areas will require active management. A series of plantings have been established on three national forests in Minnesota and Michigan to evaluate various silvicultural treatments intended to minimize the incidence of WPBR and to compare the performance of seedlings selected for disease resistance to nonselected planting stock.
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.
Danny L. Barney
During the 1800s and early 1900s, red and white currants (Ribes L. subgenus Ribes), black currants (Ribes subgenus Coreosma), and gooseberries (Ribes subgenus Grossularia) were grown commercially in the United States. Because Ribes serve as alternative hosts of white pine blister rust (Cronartium ribicola J. C. Fischer) (WPBR), which was introduced from Europe, the federal government and many states either banned or severely restricted currant and gooseberry production beginning about 1933. The development of WPBR resistant pines and black currants (the most susceptible cultivated Ribes) renewed interest in commercial Ribes production. Climatic and soil conditions in selected areas of the U.S. inland northwest and intermountain west (INIW) are favorable for commercial currant and gooseberry production. Challenges to the establishment of a Ribes industry are labor, marketing, diseases, and pests. Careful site and cultivar selection are critical for successful commercial production. This article describes Ribes opportunities and risks associated with currant and gooseberry production in the INIW. The region includes Idaho and surrounding areas in Montana, Nevada, Oregon, Utah, Washington, and Wyoming.
Fruit from black, red and white currants, and gooseberries (Ribes L.) were grown commercially in North America at the beginning of the 20th Century. However, when white pine blister rust (WPBR) (Cronartium ribicola J. C. Fisch.) was introduced into the new world, their cultivation was discontinued. About 825,000 t (908,000 tons) of Ribes fruit are produced worldwide, almost entirely in Europe. The fruit is high in vitamin C, and is used to produce juice, and many other products. Now a wide range of imported Ribes products is available particularly in Canada, and the pick-your-own (PYO) market is increasing. Two diseases, powdery mildew [Spaerotheca mors-uvae (Schwein.) Berk. & Curt.] and WPBR, are the major problems encountered by growers. Fortunately, many new cultivars are resistant to these two diseases. Commercial acreage of Ribes in North America is located where the growing day degrees above 5 °C (41 °F), and the annual chilling hours are at least 1200. Initially, the Ribes industry will develop as PYO and for farm markets. But for a large industry to develop, juice products will needed. Our costs of production figures indicate that about 850 Canadian dollars ($CDN) per 1.0 t (1.1 tons) of fruit will be required to break even.
Todd P. West, Gregory Morgenson, Larry Chaput, and Dale E. Herman
relatively pest-resistant, including good resistance to white pine blister rust ( Cronartium ribicola J.C. Fisch) ( Stephan, 2004 ). Pinus cembra cultivars have performed extremely well during periodic drought events and received no foliage needle burn as
Stanisław Pluta and Edward Żurawicz
acid. Plants are highly resistant to powdery mildew, but susceptible to white pine blister rust and anthracnose. Description Flowering and fruit. In central Poland, the bloom period of ‘Tihope’ is medium late (end of April or beginning of May depending