Search Results

You are looking at 21 - 30 of 42 items for

  • Author or Editor: Kim E. Hummer x
Clear All Modify Search

During research to develop a new germination protocol for Rubus being conducted at the National Clonal Germplasm Repository in Corvallis, we observed mixed responses to sodium hypochlorite (NaOCl) as a seed scarifying agent. For R. parviforus Nutt., scarification with NaOCl resulted in 34% germination. Fewer than 1% of the seedlings showed any negative effects after exposure to 2.6% NaOCl for 24 hours. But in R. ursinus Cham. & Schldl., R. multibracteatus A. Leveille & Vaniot, R. swinhoei Hance, and R. setchuenensis Bureau & Franchet, the percentage of injury observed ranged from 40% to 100%. In these cases, although embryonic tissue did not appear necrotic, the radicle and plumule failed to elongate after emergence. The epicotyl or primary leaves did not develop, and the radicle failed to form root hair. The cotyledons, apparently unaffected, opened and were a healthy green. NaOCl did not kill the embryo, but deterred development of the embryonic axis. As a result of the NaOCl scarification the cotyledons expanded yet the seedlings eventually died.

Free access

The National Plant Germplasm System (NPGS) of the U.S. Department of Agriculture (UDSA), Agricultural Research Service (ARS), has greatly expanded since 1980. Foremost in this expansion was the addition of seven repositories for clonally propagated fruit and specialty crops. Many collections at state agricultural experiment station sites were in jeopardy as breeders retired. These collections can now be preserved by the NPGS. The NPGS has provided funding for plant exploration and exchange. From 1980 to 2004, 37 exploration/exchange proposals for fruit crops were funded, and over 3000 accessions introduced as a result. Crop Germplasm Committees (CGCs), established for each commodity have prepared genetic vulnerability statements and prioritized collection activities. The USDA ARS, National Germplasm Resources Laboratory (NGRL), facilitates international relationships, and the USDA Animal and Plant Health Inspection Service (APHIS), National Plant Germplasm Quarantine Center (NPGQC), tests and makes pathogen-tested germplasm available. As a result of the Convention on Biological Diversity (1993) and the International Treaty on Plant Genetic Resource for Food and Agriculture (2004), the USDA now pursues germplasm collection through the establishment of bilateral agreements of mutual benefit.

Free access
Authors: and

Black currant (Ribes nigrum L.) cultivars with heavy, light, and no gooseberry mite (Cecidophyopsis grossulariae Collinge) infestation levels (MIL) were tested for cold hardiness by visually determining the bud injury rating (BIR) after laboratory freezing in Jan. 1998. Lightly mite-infested cvs. Blackdown and Risager, usually thought of as less cold hardy than Nordic cultivars, survived -35 °C, while mite-infested buds of the Finnish cv. Brödtorp were injured at -35 °C. Heavily mite-infested buds of the Swedish R. nigrum L. cv. StorKlas from Corvallis, Ore., were injured at -20 °C while lightly infested buds were injured to -25 °C. Noninfested `StorKlas' buds from Pennsylvania and British Columbia survived laboratory freezing to -35 °C. Heavy mite infestation lowered the bud cold hardiness of `Brödtorp' and `StorKlas' by 10 °C, as estimated by a modified Spearman-Karber T50, relative to the hardiness of lightly mite-infested buds of these cultivars. Heavily mite-infested buds contained unusual tissues forming what appeared to be spherical blisters or eruptions, ≈100 μ in diameter. Other tissues in the region of heavy mite infestation appeared to be more turgid than their noninfested counterparts. Abiotic and biotic stresses can have a combined impact on field-grown black currants.

Free access

A plant-collecting expedition to Iturup and Sakhalin Islands, Sakhalin Territory, Russian Federation, occurred between 21 July and 12 Sept. 2003. Strawberries, Fragaria L., were observed and collected. Japanese and Russian flora describe two diploid (2n = 2x = 14) species, F. iinumae Makino and the Yezoensis strawberry, F. nipponica Makino [syn. = Fragaria nipponica var. yezoensis (H. Hara) Kitam.], as native to those islands. In addition, a recent monograph described a new octoploid (2n = 8x = 56) strawberry species, F. iturupensis Staudt, from a Japanese herbarium specimen collected on Atsunupuri volcano near Lesozovodoskyi, Iturup, in 1929. The objectives of the 2003 collecting trip were to obtain wild strawberries from these islands and determine if a population of F. iturupensis still existed on the volcano. The native F. iinumae Makino was obtained from the Ogonki Village, Anivskyi Region, Southern Sakhalin Island, but was not observed on Iturup. The Yezoensis strawberry was observed at Cape Otlivnoy, Iturup. Two small colonies of the native octoploid F. iturupensis Staudt were collected from mid-elevations on the east-facing slope of Atsunupuri volcano. The native distribution of F. iturupensis was limited to this volcanic montane habitat and was not found in the foggy, sandy locations of coastal elevations on Iturup. The leaf morphology and growth habit of F. iturupensis plants were similar to that of F. virginiana subsp. glauca (S. Watson) Staudt of North America, but the fruit was different, more like F. vesca L. Probable cultivated escapes were observed at two sites on the east coast of Iturup and at one site in southern Sakhalin. The 2003 expedition confirmed the existence of F. iturupensis, the only known native Asian octoploid strawberry on Atsunupuri. Limited quantities of germplasm are available for research from the curator, U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository, Corvallis, OR, the U.S. national strawberry gene bank.

Free access

N.I. Vavilov, Academician of the V.I. Lenin All-Union Academy of Agricultural Sciences, takes his place as a founding pillar of knowledge in the cathedral of the origin and development of cultivated plants. Relying on the theories of his revered predecessors, Charles Darwin and Alphonse de Candolle, Vavilov developed the concept of centers of origin for agronomic crops. Vavilov’s astute hypotheses set the stage for the modern use of exotic germplasm in plant breeding. Vavilov, a devoted scientist, continued to revise and refine his theory of the centers of origin throughout his lifetime based on additional plant collections and data evaluation. Though he initially proposed three in 1924, and eight in 1935, his final papers of 1940, discussed seven major centers with some minor additions. His concept of specific centers of origin for crop plants was not an isolated aphorism but has directed breeders, on their study and reflection, to the continued improvement and economic development of plants for humanity. Inherent genetic plant variability is the basis of domestication and breeding into crops of economic importance with food, fuel, fiber, and industrial uses. The objective of this article is to present a summary of Vavilov’s plant explorations. His collection trips led to the development of his theory of the centers of origin of cultivated crops, the law of homologous variation, as well as his concept of genetic erosion. Further modification of his theories by other scientists and the impact of his ideas are mentioned. His influence on present day conservation of genetic resources are presented.

Free access

Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots and leaves of black currants (Ribes nigrum) and red currants (R. rubrum) in the Pacific northwestern U.S. Environmentally sound control measures are being sought as alternatives to sulfur or demethylation-inhibiting fungicides. This study examined the effect of mineral oil spray on powdery mildew infection in susceptible black and red currants. Mineral oil at 8 mL·L-1(8000 ppm) was applied to plants until runoff at 0-, 2-, and 4-week intervals from April through June in 1999 and 2000 on eight currant cultivars growing in Corvallis, Ore. Shoot and leaf surfaces were rated for powdery mildew incidence in early July both years. Oil applications significantly reduced mildew severity in vegetative growth as compared with that of the unsprayed control. The disease control from 2-week interval and 4-week interval oil applications was not significantly different.

Full access

Powdery mildew (Sphaerotheca mors-uvae) severely infects young leaves and stems of gooseberry (Ribes uva-crispa) throughout the world. Environmentally friendly control measures are being sought as alternatives to sulfur or demethylation inhibiting fungicides. This study examined the effect of a mineral oil spray, the biological control agent Trichoderma harzianum Rifai strain T-22 (Trichoderma), a combination mineral oil + Tricoderma, and the chemical fungicide thiophanate, on powdery mildew severity in `Industry,' a susceptible gooseberry. Mineral oil at 8 mL·L-1 (1.0 fl oz/gal), Tricoderma at 4 g·L-1 (0.5 oz/gal) and thiophanate at 1.45 mL·L-1 (0.186 fl oz/gal), and mineral oil + Tricoderma mix was applied to plants until runoff at 2-week intervals from February 2002 through April 2002, on potted `Industry' plants growing in a greenhouse in U. S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository (NCGR), Corvallis, Ore. The percent of infected leaves per plant were calculated and the percent of infected stem surface areas were visually rated in mid-April. The fungicide, mineral oil, and mineral oil + Tricoderma treatment applications significantly reduced powdery mildew severity inboth leaves and stems as compared with those of the unsprayed plants. The stem powdery mildew reduction levels of the mineral oil or a combination of mineral oil + Trichoderma treatments, were not statistically different than that of thiophanate, which is reported as commercially acceptable. We recommend mineral oil spray, or mineral oil + Tricoderma, as alternatives to fungicide control of powdery mildew on leaves and stems of young gooseberry plants.

Full access

A plant-collecting expedition to Iturup and Sakhalin Islands, Russian Federation, occurred between 21 July and 12 Sept. 2003. Actinidia, Rubus, Ribes, and Vaccinium, as well as seven accessions of strawberries, Fragaria L., were collected. Among them, a wild strawberry, Fragaria iturupensis Staudt, was collected on the eastern slope of Atsonupuri Volcano, Iturup Island, at 630 and 650 m elevation. This species was similar in habit, leaf color and overall appearance to the American strawberry species F. virginiana Mill. Fruits were bright red, oblate spherical, about 1.4 cm in diameter, and had exerted achenes. The native distribution of this species was limited to the middle elevation of the slope of this volcano, and only on Iturup Island. Chromosome counts indicated that these plants were octoploid. Initial DNA fingerprinting aligned this sample with other octoploid species. In addition to this species, samples of F. yezoensis H. Hara (syn. F. nipponica Makino) were collected on Kuibyshewskii Bay of Cape Otlivnoy, Iturup, and near Ujno-Sakhalinsk City, Sakhalin Island. F. iinumae Makino was observed in Ogon'ki Village, Sakhalin Island. This report confirmed the existence of F. iturupensis, the only known native Asian octoploid strawberry, and documented its limited range. Seeds of these strawberry species are available for research by request from the U.S. Department of Agriculture, Agricultural Research Service, National Clonal Germplasm Repository in Corvallis.

Free access

Luther Burbank, the quintessential nurseryman of the early 20th century, remarked that small fruit was the “Cinderella of the pomological family.” He stated that although tree fruits had been improved to the point of an almost uncountable number of cultivars, it was the time and responsibility of his generation and those to follow to develop the small fruit for human consumption. Burbank had a penchant for detecting potential qualities of unusual plants and his broad association with plant explorers at the U.S. Department of Agriculture and elsewhere allowed him to examine diverse wild berry species. He obtained seeds of many small fruit species from throughout the world. He made wide crosses within and between these genera and species. Burbank selected and named many cultivars to be introduced through his nursery and elsewhere. He named and released ≈40 blackberries, raspberries (Rubus L.), and strawberries (Fragaria L.); four grapes (Vitis L.); and a hybrid Solanum that he named ‘Sunberry’. He sometimes exaggerated their descriptions for promotion or public recognition. For example, Rubus ×loganobaccus ‘Phenomenal’ was, he stated, “far superior in size, quality, color, and productivity…” to ‘Loganberry’. Unfortunately, this cultivar was not a commercial success. Burbank made a few crosses and sold what he considered to be improved species, e.g., ‘Himalaya Giant’ blackberry (R. armeniacus). He created new common names for foreign species, e.g., balloon berry (R. illecebrosus) and Mayberry (R. palmatus), to better market them. However, his amazingly keen observations of thornlessness, pigment diversity, and recognition of repeat flowering and fruiting in blackberries, raspberries, and strawberries, were insightful of the needs of future industry. Burbank was a disciple of Darwin and his theory of natural selection. Burbank’s classic breeding approach, to make wide crosses, produce large numbers of hybrid seedlings, choose significant seedlings with his traits of choice, and backcross to the desired parent for several generations, was successful, although he did not know of ploidy or gene recombination. Unfortunately, the ‘Himalaya blackberry’, now ubiquitous in hedgerows and fields throughout the Pacific Northwest in the United States, is designated as a federal noxious weed. Although not presently in commercial production, three of his Rubus cultivars (‘Burbank Thornless’, ‘Snowbank’, and ‘Phenomenal’) are preserved in the U.S. Department of Agriculture, National Clonal Germplasm Repository, in Corvallis, OR.

Free access

Genetic resources of temperate berry crops were collected 7 to 27 July 2004 in Hokkaido, Japan, under a bilateral agreement between the United States and Japan. This expedition was a collaborative effort between the United States Department of Agriculture (USDA), the Japanese Ministry of Agriculture, Forestry and Fisheries (MAFF), the University of New Hampshire, and Akita Prefectural College of Agriculture, Japan. Additional assistance was provided by the Hokkaido Governmental Plant Genetic Resources Center, several Forest Research Stations of the Hokkaido University, and private botanists. The expedition obtained 100 accessions encompassing eight genera and 29 species. In all, 84 seedlots, and 23 plants were obtained. The genera collected included: Actinidia, Fragaria, Lonicera, Morus, Ribes, Rubus, Sambucus, and Vaccinium. Plant and seed accessions from this trip are preserved and distributed from the USDA ARS National Clonal Germplasm Repository in Corvallis, Ore., and from MAFF. The target genus for this expedition was Fragaria, so the trip was planned for July. Multiple samples of the two Japanese diploid strawberry species, Fragaria iinumae Makino and F. nipponica Makino (synonym = F. yezoensis H. Hara) were obtained during their prime ripening time. Ribes, Rubus, and Vaccinium fruits ripened later in the summer, but were collected when fruit were observed. Unfortunately, seeds of some of these accessions proved to be immature or nonviable upon extraction. We suggest that expeditions to collect these genera should be planned for late August. Morphological and molecular evaluation of collected germplasm is underway at the USDA ARS Corvallis Repository and at the University of New Hampshire.

Free access