scholarly journals Bacterial Blight in Carrot Seed Crops in the Pacific Northwest

Plant Disease ◽  
2005 ◽  
Vol 89 (8) ◽  
pp. 896-907 ◽  
Author(s):  
Lindsey J. du Toit ◽  
Fred J. Crowe ◽  
Mike L. Derie ◽  
Rhonda B. Simmons ◽  
Gary Q. Pelter
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
Daucus Carota ◽  
Bacterial Blight ◽  
Xanthomonas Campestris ◽  
The Pacific ◽  
Carrot Seed ◽  
Direct Seeded ◽  
Clean Seed ◽  
Seed Crops

Carrot (Daucus carota subsp. sativus) seed crops in Oregon and Washington were surveyed in 2001-02 and 2002-03 for development of Xanthomonas campestris pv. carotae, causal agent of bacterial blight. For each state and season, 20 plants were sampled from each of 7 to 12 direct-seeded crops twice in the fall or winter and three times from spring to summer; and from each of 2 to 4 steckling (root-to-seed) crops three times from spring to summer. X. campestris pv. carotae was detected in 1 of 15 and 6 of 32 stock seed lots planted in the fall in Oregon and Washington, respectively, and in 2 of 6 steckling shipments planted in each state in the spring. The pathogen was detected at 102 to 108 CFU/g foliage in 1 of 22 and 10 of 14 direct-seeded crops within 2 months of planting in 2001 and 2002, respectively. The prevalence of X. campestris pv. carotae then increased through the season in most seed crops, although bacterial blight symptoms were not observed until April in Oregon and July in Washington in both seasons. In August 2002 and 2003, X. campestris pv. carotae was detected in all 10 and 13 crops surveyed in Oregon, respectively; and in 11 of 12 and 7 of 10 crops in Washington, respectively. The pathogen was typically less prevalent in steckling versus direct-seeded crops. X. campestris pv. carotae was detected in 20 of 22 and 19 of 23 harvested seed lots in Oregon and Washington, respectively, at populations ranging from 1.3 × 101 to 1.4 × 108 CFU/g seed. Airborne X. campestris pv. carotae, detected ≤1,600 m downwind of crops being threshed in Oregon in September of 2003 and 2004, may provide a source of inoculum for newly planted seed crops between overlapping biennial seasons for carrot seed production. Despite the prevalence of this pathogen in the Pacific Northwest, carrot seed lots free of X. campestris pv. carotae were detected, demonstrating the ability to produce clean seed in this region by adhering to recommended practices for management of bacterial blight.

Insects Affecting Seed Production in Red Pine: Part I Conophthorus resinosae Hopk. (Coleoptera: Scolytidae)

1956 ◽  
Vol 88 (10) ◽  
pp. 599-608 ◽  
Author(s):  
L. A. Lyons
Keyword(s):  
Seed Production ◽  
Pacific Coast ◽  
Large Numbers ◽  
The Pacific ◽  
Future Success ◽  
Loblolly Pines ◽  
Unfavourable Weather ◽  
Cone And Seed Insects ◽  
Seed Crops ◽  
Seed Insects

Natural and artificial reforestation, which basically depend on an abundance of sound seed, are adversely affected when insects destroy large numbers of cones, seeds, and cone-bearing shoots. Other factors, such as unfavourable weather, incomplete seed development, and damage by birds and mammals also reduce seed production, but they are rarely of such widespread importance as insects, whose damage often results in the failure of seed crops over large areas. Cone and seed insects sometimes restrict the natural regeneration of trees for a few years at a time, as, for example, in conifers on the Pacific coast (16), loblolly pines in Virginia (13), and oak in Michigan (5), but they become particularly important when the seeds they destroy are required for use in artificial reforestation. The future success of much reforestation, which is inclining more and more toward the use of seed obtained from trees cultivated especially for that purpose, may largely depend on a thorough understanding of cone and seed insects and their effect on seed production.

scholarly journals Distribution of Xanthomonas hortorum pv. carotae Populations in Naturally Infested Carrot Seed Lots

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2144-2148 ◽  
Author(s):  
Jeness C. Scott ◽  
Jeremiah K. S. Dung
Keyword(s):  
Daucus Carota ◽  
Bacterial Blight ◽  
Limit Of Detection ◽  
Plant Pathogenic Bacterium ◽  
Nonnormal Distributions ◽  
Individual Seed ◽  
Seed Health ◽  
Seedborne Disease ◽  
Carrot Seed ◽  
The Mean

Bacterial blight of carrot (Daucus carota subsp. sativus), caused by the plant-pathogenic bacterium Xanthomonas hortorum pv. carotae, is a common seedborne disease of carrot wherever the crop is grown. Carrot seed lots were evaluated to determine the variability and distribution of populations of X. hortorum pv. carotae among individual carrot seeds. Twenty-four carrot seed lots harvested between 2014 and 2016 were subjected to a bulk seed wash dilution-plate assay to obtain mean X. hortorum pv. carotae levels. Mean infestation levels resulting from the bulk seed wash assays among the 24 seed lots ranged from 1.2 × 107 and 9.6 × 108 CFU/g seed and averaged 3.6 × 108 CFU/g seed. Individual seeds from the same 24 lots were also tested with a scaled-down wash assay of individual seeds. Among the 1,380 seeds that were individually assayed, 475 X. hortorum pv. carotae-positive seeds were detected (34.4%). Rates of X. hortorum pv. carotae detection on individual seed in seed lots ranged from 0% (not detected) to 97.9%, and the mean and median X. hortorum pv. carotae population on an individual seed was 8.3 × 104 and 6.3 × 101 CFU/seed, respectively. Among individual seeds, X. hortorum pv. carotae populations ranged from 2 (the limit of detection of the assay) to 3.6 × 107 CFU/seed. CFU data for 23 of the 24 seed lots were nonnormal and the Log-Logistic (3P) distribution best described populations of X. hortorum pv. carotae recovered from individual carrot seeds. The influence and impact of nonnormal distributions of X. hortorum pv. carotae in commercial carrot seed lots on seed health tests, seedborne transmission, and bacterial blight epidemiology requires further study.

scholarly journals Verticillium Wilt in Spinach Seed Production

Plant Disease ◽  
2005 ◽  
Vol 89 (1) ◽  
pp. 4-11 ◽  
Author(s):  
Lindsey J. du Toit ◽  
Mike L. Derie ◽  
Pablo Hernandez-Perez
Keyword(s):  
United States ◽  
Pacific Northwest ◽  
Seed Production ◽  
Verticillium Wilt ◽  
Spinacia Oleracea ◽  
Seed Transmission ◽  
The United States ◽  
Male And Female ◽  
Systemic Movement ◽  
The Pacific

There are no previous reports of Verticillium wilt in fresh and processing spinach (Spinacia oleracea) crops in the United States. In 2002, a hybrid spinach seed crop in the Pacific Northwest developed late-season wilt symptoms. Assays of the harvested seed and stock seed of the male and female parents revealed 59.5, 44.0, and 1.5%, respectively, were infected with Verticillium dahliae. Assays of 13 stock or commercial seed lots grown in 2002 and 62 commercial lots harvested in 2003 in Denmark, Holland, New Zealand, and the United States revealed the prevalence of Verticillium spp. in commercial spinach seed. Sixty-eight lots (89%) were infected with Verticillium spp. at incidences ranging from 0.3 to 84.8%. Five spinach seed isolates of V. dahliae were pathogenic on each of three spinach cultivars by root-dip inoculation. V. dahliae was detected on 26.4% of the seed from 7 of 11 inoculated plants but on none of the seed from 6 control plants, demonstrating systemic movement of V. dahliae. Seed-to-seed transmission was also demonstrated by planting naturally infected seed lots. This is the first report of Verticillium wilt of spinach in the primary region of spinach seed production in the United States.

scholarly journals Suppression of Wheat Growth and Yield by Pratylenchus neglectus in the Pacific Northwest

Plant Disease ◽  
2005 ◽  
Vol 89 (9) ◽  
pp. 958-968 ◽  
Author(s):  
Richard W. Smiley ◽  
Ruth G. Whittaker ◽  
Jennifer A. Gourlie ◽  
Sandra A. Easley
Keyword(s):  
Pacific Northwest ◽  
Initial Density ◽  
Canopy Temperature ◽  
Gaeumannomyces Graminis ◽  
Growth And Yield ◽  
Heterodera Avenae ◽  
Pratylenchus Neglectus ◽  
The Pacific ◽  
Direct Seeded ◽  
Moderately Resistant

Many wheat (Triticum aestivum) fields planted annually in the Pacific Northwest are infested by high populations of the lesion nematode, Pratylenchus neglectus. Spring wheat cultivars varying in tolerance and resistance to P. neglectus were treated or not treated with aldicarb to examine relationships between the nematode and growth and yield of annual direct-seeded (no-till) wheat. Increasing initial density of P. neglectus in soil was more strongly associated with declining growth and yield of intolerant (Machete and Spear) than moderately tolerant (Frame and Krichauff) cultivars. Yield suppression by P. neglectus was generally 8 to 36% for intolerant cultivars, but reached 71% in soil also harboring Heterodera avenae, Rhizoctonia solani AG-8, and Gaeumannomyces graminis var. tritici. Intolerant cultivars had lower yields than Krichauff in rainfed but not in irrigated experiments. Density of P. neglectus in mature roots was generally lower for moderately resistant Krichauff than for susceptible Machete and Spear. Aldicarb improved yields in irrigated but not in rainfed experiments, and increased plant height and reduced variability in tiller height, canopy temperature, and density of P. neglectus in roots. This is the first report of damage to wheat by P. neglectus in the Pacific Northwest. Breeding wheat for tolerance and resistance to P. neglectus is suggested.

Crop density and seed production of creeping red fescue (Festuca rubra L. var. rubra). 1. Yield and plant development

1996 ◽  
Vol 76 (2) ◽  
pp. 291-298 ◽  
Author(s):  
N. A. Fairey ◽  
L. P. Lefkovitch
Keyword(s):  
Population Density ◽  
Seed Production ◽  
Seed Yield ◽  
Row Spacing ◽  
Initial Population ◽  
Festuca Rubra ◽  
Initial Population Density ◽  
Red Fescue ◽  
Clean Seed ◽  
Seed Crops

The natural growth habit of creeping red fescue (Festuca rubra L. var. rubra) involves a steady proliferation of tillers, which eventually become too dense to form seedheads. A field study was conducted to evaluate whether seed yield of fescue can be optimized for one, two or three consecutive crops by manipulating the initial population density and arrangement of plants. Individual seedling plants were transplanted at seven densities (1.6, 3.1, 6.3, 12.5, 25, 50 and 100 plants m−2) and three row spacings (20, 40 and 80 cm), and characteristics of seed production were determined for 3 yr (1991–1993). Heading commenced at dates differing by 16 d in the 3 yr and was delayed by up to 7 d as density increased. Seed maturity occurred in a 7-d period in each year (15–22 July). For a single harvest, an initial density of 12–100 plants m−2 on a row spacing of 20 cm or 12–50 plants m−2 on a row spacing of 40 cm is required to optimize yield and produce about 600 kg ha−1 of clean seed. For two consecutive harvests, an initial population density of 6–25 plants m−2 on a row spacing of 20 cm or 6–50 plants m−2 on a row spacing of 40 cm is required to optimize yield and produce a total of about 800 kg ha−1 of clean seed. For producing for either 1 or 2 yr, a density of 12–25 plants m−2 on rows no wider than 40 cm is required to optimize seed yield in each year. The probability of producing a third seed crop decreases markedly as the initial plant density increases and as the row spacing decreases. It is probably uneconomic to harvest more than two consecutive seed crops with current management practices. Key words: Red fescue; Festuca rubra var. rubra, population density, plant spacing, seed production

Seed Retention of Grass Weeds at Wheat Harvest in the Pacific Northwest

Weed Science ◽  
2020 ◽  
pp. 1-32
Author(s):  
Carolina San Martín ◽  
Mark E Thorne ◽  
Jennifer A Gourlie ◽  
Drew J Lyon ◽  
Judit Barroso
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
Secale Cereale ◽  
Bromus Tectorum ◽  
Wheat Crop ◽  
Weed Seed ◽  
Weed Species ◽  
Seed Shattering ◽  
Seed Retention ◽  
The Pacific

Abstract Harvest weed seed control (HWSC) may control problematic weeds by decreasing contributions to the weed seed bank. However, HWSC practices will not be effective if plants have shed a great part of their seeds before harvest, or if a low proportion of seed production is retained at a height that enables collection during harvest. The seed shattering pattern of several weed species was evaluated over three growing seasons to determine their potential to be controlled with HWSC in the Pacific Northwest (PNW). The studied weed species were downy brome (Bromus tectorum L.), feral rye (Secale cereale L.), Italian ryegrass [Lolium perenne ssp. multiflorum (Lam.) Husnot,], and rattail fescue [Vulpia myuros (L.) C.C. Gmel.]. Seed retention at harvest, seed production, and plant height differed among species, locations, and years. Environmental conditions influenced seed shattering patterns, particularly the time plants started to shatter seeds and the rate of the shattering. Agronomic factors such as herbicide use, inter-row space, or crop height/vigor also seemed to affect shattering patterns and seed production, but more specific studies must be conducted to determine their individual effects. Bromus tectorum, L. perenne ssp. multiflorum, and V. myuros had an average seed retention at harvest of less than 50%. In addition, the low seed retention height of V. myuros makes this species a poor candidate for HWSC. Secale cereale had average seed retention at harvest greater than 50% and seed retention height was greater than 30 cm. The variability of seed retention in different species will make the efficacy of HWSC practices species and environment dependent in PNW winter wheat cropping systems. Harvesting the wheat crop as early as possible will be crucial to the success of HWSC.

scholarly journals Isolation Distances for Transgenic Alfalfa Seed Production in the Pacific Northwest

Crop Science ◽  
2019 ◽  
Vol 59 (4) ◽  
pp. 1701-1708
Author(s):  
Sandya R. Kesoju ◽  
Stephanie L. Greene ◽  
Ruth C. Martin ◽  
Matthew Kramer ◽  
Douglas B. Walsh ◽  
...  
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
Transgenic Alfalfa ◽  
The Pacific ◽  
Alfalfa Seed ◽  
Isolation Distances

scholarly journals First Report of Garlic virus B and Garlic virus D in Garlic in the Pacific Northwest

Plant Disease ◽  
2009 ◽  
Vol 93 (4) ◽  
pp. 431-431 ◽  
Author(s):  
S. L. Gieck ◽  
P. B. Hamm ◽  
N. L. David ◽  
H. R. Pappu
Keyword(s):  
Pacific Northwest ◽  
Seed Production ◽  
The Other ◽  
Rt Pcr ◽  
Specific Primers ◽  
Sequence Comparisons ◽  
First Report ◽  
The Pacific ◽  
The Impact ◽  
Garlic Virus

With the recent report of several viruses infecting garlic (Allium sativum L.) grown in the Pacific Northwest (1–3), studies were initiated on cloves planted in the fall of 2006 to determine the presence of additional viruses infecting plants exhibiting mosaic and/or chlorotic leaves. Cloves from symptomatic plants of the cultivar ‘Early’ from two seed production fields in Benton County, WA and two seed production fields in Morrow County, OR were tested by two-step reverse transcription (RT)-PCR using primers specific to the coat protein (CP) of the allexiviruses (4), since garlic infected with this group had similar symptoms in Asia and South America (4). Of the 87 cloves tested, 84 were positive, and four representative samples of the RT-PCR amplicons from each location were cloned and sequenced. Sequence comparisons indicated that the cloves from both locations were infected with Garlic virus D (GarV-D), also known as Japanese garlic virus (JGV), since they shared 98% identity with known isolates (GenBank Accession Nos. L388922.1, AF519572.1, and AB010303.1). In addition, sequences of isolates from the Oregon cloves shared a 96% identity with a known isolate of Garlic virus B (GarV-B; GenBank Accession No. AF543829.1). Because no antiserum specific to these viruses was available, primers specific to the CP genes of GarV-D (JGV-F2/JGV-R2 5′-GCTCACTCRGATGTGTTAGC-3′ and 5′-CGCGTGGACATAAGTTGTTG-3′) and GarV-B (GVB-F1/GVB-R2 5′-GAGGAGAACTAACGCCACAC-3′ and 5′-ACGACCTAGCTTCCTACTTG-3′) were designed and the cloves were retested by RT-PCR using these virus-specific primers. With the GarV-D specific primers, 98 and 63% of the cloves were positive from Washington and Oregon, respectively, and 52% of the cloves from Oregon were positive using the GarV-B specific primers. None of the cloves tested from Washington were positive for GarV-B. The identity of the amplicons was verified by cloning and sequencing (GarV-D, GenBank Accession No. FJ643476; GarV-B, GenBank Accession No. FJ643475). Incidence of the two viruses differed between Oregon and Washington was likely due to the expansion of the seed lots in two different locations (California and Nevada) prior to planting in 2006. With such high infection rates, studies should be conducted to determine the impact of these viruses on yield when plants are singly infected as well as in combination with the other viruses known to infect garlic in this region. These and the other viruses (1) are likely to impact yield. To our knowledge, this is the first report of GarV-D (JGV) and GarV-B in garlic in the Pacific Northwest. References: (1) S. L. Gieck et al. Plant Dis. 91:461, 2007. (2) H. R. Pappu et al. Plant Dis. 89:205, 2005 (3) H. R. Pappu et al. Online publication. doi:10.1094/PHP-2008-0919-01-RS. Plant Health Progress, 2008. (4) T. Tsuneyoshi et al. Phytopathology 86:253, 1996.

scholarly journals Seed Contamination Thresholds for Development of Carrot Bacterial Blight Caused by Xanthomonas campestris pv. carotae

Plant Disease ◽  
1998 ◽  
Vol 82 (11) ◽  
pp. 1271-1275 ◽  
Author(s):  
K. C. Umesh ◽  
R. M. Davis ◽  
R. L. Gilbertson
Keyword(s):  
Relative Humidity ◽  
Daucus Carota ◽  
Bacterial Blight ◽  
Xanthomonas Campestris ◽  
Disease Incidence ◽  
Contamination Levels ◽  
The Relationship ◽  
Field Plots

The relationship between levels of carrot (Daucus carota subsp. sativus) seed contamination with Xanthomonas campestris pv. carotae and (i) establishment of populations of X. campestris pv. carotae on carrot leaves and (ii) the incidence and severity of carrot bacterial blight was determined in field plots in Davis, California, in 1995 and 1996. Levels of seed contamination ranged from 0 to 1.5 × 105 CFU/g in 1995 and from 0 to 1.5 × 107 CFU/g in 1996. Seed contamination levels were positively correlated with X. campestris pv. carotae populations detected on leaves and with the incidence and severity of carrot bacterial blight. The size of X. campestris pv. carotae populations on leaves was also directly related to disease incidence. In 1996, yields were significantly reduced in plots established with seed lots having the highest levels of X. campestris pv. carotae contamination. Under the conditions of this study (i.e., a location having low rainfall and relative humidity), the threshold of seed contamination for the establishment of X. campestris pv. carotae populations on leaves and for the development of carrot bacterial blight was unexpectedly high: 104 to 105 CFU/g of seed.

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