Search Results

You are looking at 1 - 10 of 44 items for :

  • rust fungus x
  • User-accessible content x
Clear All
Free access

Guojing Li, Yonghua Liu, Jeffrey D. Ehlers, Zhujun Zhu, Xiaohua Wu, Baogeng Wang, and Zhongfu Lu

and southeast Asia, and its use is increasing in many other parts of the world. Rust disease, incited by the fungus Uromyces vignae , adversely affects production and quality of asparagus bean throughout this region ( Wang, 2004 ) and is an important

Free access

Phillip N. Miklas and J. Rennie Stavely

Foliar diseases are a major constraint to cultivated tepary bean (Phaseolus acutifolius A. Gray var. latifolius Freeman) production in some environments. The reactions of 12 cultivated teparies to eight individual races (41, 47, 49, 51, 53, 58, 67, and 73) of the bean rust fungus Uromyces appendiculatus (Pers.) Unger var. appendiculatus maintained at Beltsville, Md., were examined under greenhouse conditions. These diverse races, used together, overcome all of the major rust-resistance genes present within the 19 host differential cultivars of common bean (Phaseolus vulgaris L.). Seven lines (GN-605-s, GN-610-s, PI 321638-s, PI 502217-s, Neb-T-6-s, Neb-T-8a-s, and Neb-T-15-s) exhibited similarly high levels of resistance (immunity or necrotic spots without sporulation) to all eight races. Inheritance of resistance was examined across five susceptible × resistant (S × R) and three resistant × resistant (R × R) populations. The rust reactions in the F1, F2, and F3 generations derived from S × R crosses revealed that the immune or necrotic resistance response was conditioned by a single locus exhibiting incomplete dominance. The rust resistance of four lines tested for allelism in R × R crosses was found to be derived from the same gene. This apparent lack of variability for rust resistance suggests that a single introgression event may realize the full potential for cultivated tepary bean to contribute rust resistance to common bean through interspecific hybridization. In addition, the limited variability for resistance to the highly variable rust pathogen in cultivated tepary bean supports the occurrence of a “bottleneck effect” during domestication of this species, as observed in germplasm diversity studies.

Free access

Lisa A. Beirn, William A. Meyer, Bruce B. Clarke, and Jo Anne Crouch

became apparent that leaf spot–resistant cultivars such as Merion were highly susceptible to stem rust disease caused by the fungus P. graminis ( Ray, 1953 ). It is now common practice for turfgrass breeding programs to evaluate new sources of germplasm

Free access

M.E. Ostry

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.

Free access

Charles J. Wasonga, Marcial A. Pastor-Corrales, Timothy G. Porch, and Phillip D. Griffiths

Internacional de Agricultura Tropical, 2006 ). Common bean rust, caused by the basidiomycete fungus Uromyces appendiculatus , is a destructive disease of dry and snap beans worldwide and is a particularly endemic and severe disease in eastern and southern

Free access

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.

Free access

Todd A. Burnes, Robert A. Blanchette, Jason A. Smith, and James J. Luby

can serve as alternate hosts for Cronartium ribicola , the causal agent of white pine blister rust (WPBR). This disease was introduced into North America over 100 years ago and has caused major mortality to native five-needle pines. Once the Ribes

Full access

Eugene K. Blythe, Cecil Pounders, Michael Anderson, Earl Watts, and Barbara Watts

, 1991 ; Stout, 1986 ). Daylily flowers may be used to flavor and garnish culinary dishes ( Pollard et al., 2004 ). Daylily generally has few insect and disease pests in the landscape; however, daylily rust, caused by the fungus Puccinia hemerocallidis

Free access

Charles J. Wasonga, Marcial A. Pastor-Corrales, Timothy G. Porch, and Phillip D. Griffiths

in particular, common bean rust caused by the fungus Uromyces appendiculatus, which can severely limit the yield and quality of the snap bean crops ( CIAT, 2006 ; Wasonga et al., 2010 ; Wortmann et al., 1998 ). Rust is a destructive disease of

Free access

John A. Muir and Richard S. Hunt

Introductions of white pine blister rust (WPBR, causal fungus: Cronartium ribicola J.C. Fischer) to eastern and western North America before 1915 caused such extensive damage that western white pine (Pinus monticola D. Don) was essentially abandoned as a manageable forest tree species for over 60 years. Recent results from WPBR resistance selection and breeding programs, and from field trials of tree spacing, pruning and bark excision treatments have supported efforts to increase establishment and to intensively manage western white pine. Western white pine is a desirable component in many forested areas because of its faster growth and much higher value compared to many other associated tree species. It also has a low susceptibility to armillaria root disease caused by Armillaria ostoyae (Romagnesi) Herink and laminated root rot, caused by Phellinus weirii (Murr.) Gilb. Some regulations, e.g., Forest Practices Code of British Columbia (BC) Act, require anyone who harvests timber on provincial forestland and uses western white pine for reforestation to either plant genetically resistant western white pine stock or prune susceptible young trees for protection. Risks of increased WPBR associated with increased commercial cultivation of gooseberries and currants (Ribes L.) have yet to be determined. However, major threats appear to include 1) increase in local amounts of spores for nearby infection of pines; and 2) possible introductions or development of new, virulent races of C. ribicola, particularly from eastern to Pacific northwestern North America. In view of these possible threats, we recommend that existing regulations and legislation should be amended, or possibly new measures enacted, to permit propagation and commercial cultivation only of varieties of Ribes that are immune or highly resistant to WPBR.