scholarly journals Prevalence of Acidovorax citrulli in Commercial Cucurbit Seedlots During 2010–2018 in China

Plant Disease ◽  
2020 ◽  
Vol 104 (1) ◽  
pp. 255-259 ◽  
Author(s):  
Yanli Tian ◽  
Yuqiang Zhao ◽  
Jiaju Zhou ◽  
Ting Sun ◽  
Xue Luo ◽  
...  
Keyword(s):  
Seed Production ◽  
Inner Mongolia ◽  
Fruit Production ◽  
Colony Pcr ◽  
Primary Inoculum ◽  
Bacterial Fruit Blotch ◽  
Growing Seasons ◽  
Acidovorax Citrulli ◽  
High Prevalence ◽  
Production Areas

Acidovorax citrulli is the causal agent of bacterial fruit blotch (BFB), a serious threat to cucurbit fruit and seed production worldwide. In recent years, the BFB has spread to many areas of China, mainly via the inadvertent distribution of contaminated commercial seeds. To assess the prevalence of seedborne A. citrulli in commercial watermelon and other cucurbitaceous seedlots in China, a 9-year survey was conducted between 2010 and 2018. A total of 4,839 seedlots of watermelon and other cucurbitaceous species were collected from 13 major seed production areas of China and tested by a semiselective media-based colony PCR technique for A. citrulli. Overall, A. citrulli was detected in 18.00% (871/4,839) of all cucurbitaceous seedlots. The bacterium was detected in 21.59% (38/176), 19.19% (33/172), 23.44% (214/913), 40.76% (247/606), 13.28% (85/640), 15.40% (95/617), 13.25% (73/551), 8.03% (48/598), and 6.71% (38/566) of all commercial seedlots tested from the 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, and 2018 growing seasons, respectively. Additionally, the prevalence of A. citrulli in cucurbit seedlots was determined for different seed production areas. The prevalence of A. citrulli in cucurbitaceous seedlots produced in Xinjiang, Gansu, Ningxia, Inner Mongolia, and 9 other provinces was 18.76% (582/3103), 26.34% (103/391), 21.47% (82/382), 11.11% (14/126), and 10.75% (90/837), respectively. This is the first survey for A. citrulli in commercial cucurbit seeds in China, and the relatively high prevalence suggests that commercial seeds represent a substantial source of primary inoculum that can threaten cucurbit seed and fruit production in China.

scholarly journals Efficacy of a Nonpathogenic Acidovorax citrulli Strain as a Biocontrol Seed Treatment for Bacterial Fruit Blotch of Cucurbits

Plant Disease ◽  
2011 ◽  
Vol 95 (6) ◽  
pp. 697-704 ◽  
Author(s):  
K. L. Johnson ◽  
G. V. Minsavage ◽  
T. Le ◽  
J. B. Jones ◽  
R. R. Walcott
Keyword(s):  
Biological Control ◽  
Seed Treatment ◽  
Management Strategies ◽  
Fruit Production ◽  
Management Program ◽  
Control Seed ◽  
Bacterial Fruit Blotch ◽  
Watermelon Seed ◽  
Acidovorax Citrulli ◽  
Phosphate Buffered Saline

Bacterial fruit blotch (BFB), caused by the seedborne, gram-negative bacterium Acidovorax citrulli, is a serious threat to cucurbit seed and fruit production worldwide. Because of the lack of effective management strategies, we investigated the efficacy of a nonpathogenic A. citrulli strain as a biological control seed treatment for BFB. For this study, we generated a type III secretion system mutant of A. citrulli, AAC00-1ΔhrcC, that was nonpathogenic on watermelon but retained its ability to colonize germinating watermelon seed. With watermelon seed naturally infested with A. citrulli, AAC00-1ΔhrcC reduced BFB seedling transmission by 81.8% relative to control seed. In comparison, another A. citrulli antagonist, A. avenae strain AAA 99-2, reduced BFB seedling transmission by 74.6% for seed samples from the same lot. Additionally, when female watermelon blossoms were protected with AAC00-ΔhrcC and subsequently challenged with AAC00-1, the resulting seedlots displayed 8% BFB seedling transmission. This was not significantly different than seed from blossoms protected with AAA 99-2 (4%) but significantly less than those from blossoms protected with 0.1 M phosphate-buffered saline (36%). These results suggest that nonpathogenic A. citrulli has potential as a biological control seed treatment component in a comprehensive BFB management program.

scholarly journals Production Steps to Reduce Seed Contamination by Pathogens of Cucurbits

2003 ◽  
Vol 13 (1) ◽  
pp. 50-54 ◽  
Author(s):  
Branko R. Lovic ◽  
Donald L. Hopkins
Keyword(s):  
Seed Production ◽  
Continuous Monitoring ◽  
Pathogenic Bacteria ◽  
Significant Risk ◽  
Disease Symptoms ◽  
Bacterial Fruit Blotch ◽  
Seed Harvest ◽  
Bacteria And Fungi ◽  
Production Areas ◽  
Disease Pressure

Selecting production areas for low disease pressure, implementation of preventive spray programs, and continuous monitoring for disease symptoms are important steps to keep seed production fields free of potentially seedborne diseases, such as bacterial fruit blotch of cucurbits (Cucurbitaceae), caused by Acidovorax avenae ssp. citrulli. However, seeds of cucurbit crops and other fleshy vegetables typically remain remarkably free of pathogenic bacteria and fungi while in intact fruit. The most significant risk for seed contamination comes at harvest when the inoculum present in the field or in the seed harvesting area may contaminate the seeds. Properly executed fermentation and seed drying processes significantly reduce seed contamination. Application of a no-rinse disinfectant formulation to freshly harvested seed just before drying may be the single most efficacious procedure to reduce the seed contamination risk. However, the disinfection step should not be expected to be effective unless applied as part of a fully controlled seed harvest process.

Natural establishment of Pinus spp. around seed production areas and orchards

2021 ◽  
Vol 494 ◽  
pp. 119333
Author(s):  
Magda Paula dos Santos ◽  
Marcio José de Araujo ◽  
Paulo Henrique Müller da Silva
Keyword(s):  
Seed Production ◽  
Natural Establishment ◽  
Pinus Spp ◽  
Production Areas

scholarly journals Rattail fescue (Vulpia myuros) interference and seed production as affected by sowing time and crop density in winter wheat

Weed Science ◽  
2020 ◽  
pp. 1-10
Author(s):  
Muhammad Javaid Akhter ◽  
Per Kudsk ◽  
Solvejg Kopp Mathiassen ◽  
Bo Melander
Keyword(s):  
Winter Wheat ◽  
Grain Yield ◽  
Seed Production ◽  
Yield Components ◽  
Field Experiments ◽  
Growing Season ◽  
Sowing Time ◽  
Growing Seasons ◽  
Crop Density ◽  
Wide Range

Abstract Field experiments were conducted in the growing seasons of 2017 to 2018 and 2018 to 2019 to evaluate the competitive effects of rattail fescue [Vulpia myuros (L.) C.C. Gmel.] in winter wheat (Triticum aestivum L.) and to assess whether delayed crop sowing and increased crop density influence the emergence, competitiveness, and fecundity of V. myuros. Cumulative emergence showed the potential of V. myuros to emerge rapidly and under a wide range of climatic conditions with no effect of crop density and variable effects of sowing time between the two experiments. Grain yield and yield components were negatively affected by increasing V. myuros density. The relationship between grain yield and V. myuros density was not influenced by sowing time or by crop density, but crop–weed competition was strongly influenced by growing conditions. Due to very different weather conditions, grain yield reductions were lower in the growing season of 2017 to 2018 than in 2018 to 2019, with maximum grain yield losses of 22% and 50% in the two growing seasons, respectively. The yield components, number of crop ears per square meter, and 1,000-kernel weight were affected almost equally, reflecting that V. myuros’s competition with winter wheat occurred both early and late in the growing season. Seed production of V. myuros was suppressed by delaying sowing and increasing crop density. The impacts of delayed sowing and increasing crop density on seed production of V. myuros highlight the potential of these cultural weed control tactics in the long-term management programs of this species.

scholarly journals Development of Molecular Markers for Detection of Acidovorax citrulli Strains Causing Bacterial Fruit Blotch Disease in Melon

2019 ◽  
Vol 20 (11) ◽  
pp. 2715 ◽  
Author(s):  
Md. Rafiqul Islam ◽  
Mohammad Rashed Hossain ◽  
Hoy-Taek Kim ◽  
Denison Michael Immanuel Jesse ◽  
Md. Abuyusuf ◽  
...  
Keyword(s):  
Infected Leaf ◽  
Bacterial Fruit Blotch ◽  
Early Disease Detection ◽  
Acidovorax Citrulli ◽  
Seed Health ◽  
Field Samples ◽  
Whole Genomes ◽  
Pathogenesis Related ◽  
Primer Sets ◽  
Inoculation Assay

Acidovorax citrulli (A. citrulli) strains cause bacterial fruit blotch (BFB) in cucurbit crops and affect melon significantly. Numerous strains of the bacterium have been isolated from melon hosts globally. Strains that are aggressively virulent towards melon and diagnostic markers for detecting such strains are yet to be identified. Using a cross-inoculation assay, we demonstrated that two Korean strains of A. citrulli, NIHHS15-280 and KACC18782, are highly virulent towards melon but avirulent/mildly virulent to the other cucurbit crops. The whole genomes of three A. citrulli strains isolated from melon and three from watermelon were aligned, allowing the design of three primer sets (AcM13, AcM380, and AcM797) that are specific to melon host strains, from three pathogenesis-related genes. These primers successfully detected the target strain NIHHS15-280 in polymerase chain reaction (PCR) assays from a very low concentration of bacterial gDNA. They were also effective in detecting the target strains from artificially infected leaf, fruit, and seed washing suspensions, without requiring the extraction of bacterial DNA. This is the first report of PCR-based markers that offer reliable, sensitive, and rapid detection of strains of A. citrulli causing BFB in melon. These markers may also be useful in early disease detection in the field samples, in seed health tests, and for international quarantine purposes.

scholarly journals Bacteriophage Biocontrol of Acidovorax citrulli, the Causal Agent of Bacterial Fruit Blotch

Proceedings ◽  
2020 ◽  
Vol 50 (1) ◽  
pp. 10
Author(s):  
Aryan Rahimi-Midani ◽  
Tae-Jin Choi
Keyword(s):  
Crop Production ◽  
Germination Rate ◽  
Causal Agent ◽  
Head Size ◽  
Genotype I ◽  
Bacterial Fruit Blotch ◽  
Double Stranded Dna ◽  
Acidovorax Citrulli ◽  
Group I ◽  
Next Generation Sequencing Ngs

Bacterial fruit blotch caused by Acidovorax citrulli is known to be the major threat to cucurbit crop production worldwide. The pathogen can penetrate into seed coat and cause disease symptoms at any stage of plant growth, which results in fruit loss. Two main genotypes (genotype I and II) are reported in A. citrulli, in which genotype II is the main cause of Bacterial Fruit Blotch (BFB) in watermelon and group I is known to be a causal agent of BFB in melon. To date, there are no commercially available cultivars resistant to BFB, and available strategies are not able to completely manage the disease. In this study, we aim to isolate bacteriophages to control BFB. Samples collected from watermelon, melon, and pumpkin were used to isolate bacteriophages. All isolated bacteriophages were tested against 42 strains of A. citrulli, among which two phages with the ability to lyse a greater number of hosts were selected and characterized. Bacteriophage ACP17 from the Myoviridae family, with a head size of 100 ± 5 nm and tail of 150 ± 5 nm, infected 29 strains of A. citrulli mostly belonging to genotype group I, whereas the second isolated bacteriophage, ACPWH from Siphoviridae, with a head size of 60 ± 5 nm and tail of 180 ± 5 nm, infected 39 A. citrulli strains. Genome analysis of both bacteriophages using Next generation Sequencing (NGS) showed that ACP17 and ACPWH have double-stranded DNA with sizes of 156,972 kb and 424,299 kb, respectively. Watermelon seeds coated with ACPWH showed a germination rate of up to 90% in the presence of A. citrulli in contrast to untreated seed, which showed no germination or germinated juveniles with BFB symptoms in the presence of A. citrulli. The results of this study show that the use of bacteriophages of A. citrulli represents a potential biocontrol method for controlling BFB.

scholarly journals DETEKSI PENYAKIT BACTERIAL FRUIT BLOTCH PADA MELON MENGGUNAKAN ELISA (DETECTION OF BACTERIAL FRUIT BLOTCH OF MELON USING ELISA)

2016 ◽  
Vol 19 (1) ◽  
pp. 1
Author(s):  
Utik Windari ◽  
Tri Joko ◽  
Siti Subandiyah
Keyword(s):  
Detection Method ◽  
Yield Losses ◽  
Elisa Method ◽  
Bacterial Fruit Blotch ◽  
Acidovorax Citrulli ◽  
Commercial Seed ◽  
Seedborne Disease ◽  
Dark Green ◽  
Das Elisa ◽  
Special Region

Bacterial fruit blotch (BFB) caused by Acidovorax citrulli is a serious seedborne disease in Cucurbitaceae causing 90-100% yield losses. The aim of this study was to explore BFB symptom on melon and also to detect A. citrulli infection in commercial seed and symptomatic fruits from the field in Yogyakarta Special Region province and its surrounding using DAS-ELISA method. Samples include melon from Sleman, Bantul, Kulon Progo, Gunung Kidul, Magelang, Purworejo regencies while commercial seeds i.e. Action 434, Glamour and Mai 116 were collected. DASELISA detection method used reagent set from Agdia. Based on the field observation, this study found melon commercial fruit shares similar symptom with BFB, which showed discrete oily dark green spots, while the netting failed to develop over necrotic areas, resulting in smooth sunken spots. DAS-ELISA detection revealed that samples collected from Jetak village, district of Mungkid, Magelang and from Bligo village, district of Ngluwar, Magelang and in commercial seed Mai 116 were positively infected byA. citrulli.Keywords: Acidovorax citrulli, bacterial fruit blotch, ELISA, melonBacterial fruit blotch (BFB) merupakan penyakit penting pada famili Cucurbitaceae yang disebabkan oleh Acidovorax citrulli. Penyakit ini dilaporkan dapat menurunkan hasil mencapai 90-100%. Tujuan dari penelitian ini adalah untuk mengetahui gejala penyakit BFB pada melon dan deteksiA. citrulli pada benih komersial dan sampel buah bergejala dengan metode DAS-ELISA di DIY dan sekitarnya. Pengambilan sampel dilakukan di kabupaten Sleman, Bantul, Kulon Progo, Gunung Kidul, Purworejo dan Magelang. Selain dari lapangan, diuji pula benih melon komersial yaitu Action-434, Glamour dan Mai 116. Metode deteksi dengan ELISA menggunakanreagent set dari Agdia. Dari hasil pengamatan di lapangan ditemukan buah melon dengan gejala yang mirip dengan gejala BFB yaitu adanya becak berwarna hijau tua kebasahan pada permukaan buah, jaring tidak terbentuk sempurna dan pada bagian daging buah di bawah becak tadi membusuk. Hasil deteksi dengan DAS-ELISAmengindikasikan bahwa A. citrulli terdeteksi pada sampel yang berasal dari desa Bligo, kecamatan Ngluwar dan desa Jetak, kecamatan Mungkid, kabupaten Magelang, serta pada benih komersial MAI 116.Kata kunci: Acidovorax citrulli, bacterial fruit blotch, ELISA, melon

scholarly journals Nitrogen Fertilizer Management Practices to Enhance Seed Production by `Anaheim Chili' Peppers

1990 ◽  
Vol 115 (2) ◽  
pp. 245-251 ◽  
Author(s):  
J.O. Payero ◽  
M.S. Bhangoo ◽  
J.J. Steiner
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Management Practices ◽  
Irrigation System ◽  
Seed Mass ◽  
Fruit Production ◽  
Trickle Irrigation ◽  
Total N ◽  
Leaf Petiole ◽  
Total Seed

The effects of six applied N treatments differing by rates and frequencies of application on the yield and quality of pepper (Capsicum annuum var. annuum L. `Anaheim Chili') grown for seed was studied. The timing of N applications was based on crop phenology, leaf petiole nitrate-nitrogen concentrations (NO3-N) minimum thresholds, and scheduled calendar applications of fixed amounts of N. Solubilized NH4NO3 was applied through a trickle-irrigation system to ensure uniform and timely applications of N. Rate of mature (green and red) fruit production was unaffected by any treatment except weekly applications of 28 kg·ha-1 of N, which stopped production of mature fruit before all other treatments. Early season floral bud and flower production increased with increasing amounts of N. The two highest total N treatments produced more floral buds and flowers late in the season than the other treatments. Total fruit production was maximized at 240 kg N/ha. Differences in total fruit production due to frequency of N application resulted at the highest total N level. Red fruit production tended to be maximized with total seasonal applied N levels of 240 kg·ha-1 and below, although weekly applications of N reduced production. Total seed yield was a function of red fruit production. Pure-1ive seed (PLS) production was a function of total seed production. Nitrogen use efficiency (NUE) for red fruit production also decreased with N rates >240 kg·ha-1, but PLS yield and NUE decreased in a near-linear fashion as the amount of total seasonal applied N increased, regardless of application frequency. Season average NO3-N (AVE NO3-N) values >4500 mg·kg-1 had total seed and PLS yields less than those treatments <4000 mg·kg-1. Six-day germination percentage was reduced with weekly N applications of 14 kg·ha-1. Seed mass was reduced with weekly N applications of 28 kg·ha-1. Final germination percent, seedling root length and weight, and field emergence were unaffected by any of the N treatments. These findings indicate that different N management strategies are needed to maximize seed yield compared to fruit yield and, therefore, there may be an advantage to growing `Anaheim Chili' pepper specifically for seed.

scholarly journals First Report of Umbel Browning and Stem Necrosis Caused by Diaporthe angelicae on Carrot in France

Plant Disease ◽  
2014 ◽  
Vol 98 (3) ◽  
pp. 421-421 ◽  
Author(s):  
L. Ménard ◽  
P. E. Brandeis ◽  
P. Simoneau ◽  
P. Poupard ◽  
I. Sérandat ◽  
...  
Keyword(s):  
Seed Production ◽  
White Light ◽  
Agar Medium ◽  
Malt Agar ◽  
Universal Primers ◽  
Conidial Suspension ◽  
First Report ◽  
Daucus Carota L ◽  
Cropping Seasons ◽  
Production Areas

In 2011, carrot (Daucus carota L.) seed production occurred on 2,900 ha, which accounts for approximately 25% of the area devoted to the production of vegetable fine seeds. Since 2007, symptoms of umbel browning have been regularly observed in carrot production areas located in the central region. Initially, triangular necrotic lesions appeared on carrot umbels that later spread to the entire umbels and often progressed to the stems. Diseased umbels became dried prematurely, compromising seed development. The loss in seed production was estimated at approximately 8% of the harvested carrot umbels during the cropping seasons of spring and summer 2007 and 2008 in France. In collaboration with seed companies, diseased carrot stems were collected from seven fields of seed production (eight plants per field) and a fungus was isolated from the tissue. The cultures were grown on malt (2%) agar (1.5%) medium and incubated for 2 weeks at 22°C in darkness. Young fungal colonies were white and a brownish green pigmentation developed when the colonies became older. The same color was observed from the top and on the reverse of the colonies. To induce sporulation, isolates were grown on water agar (1.5%) medium in the presence of carrot stem fragments for 1 week at 22°C in darkness, followed by 1 week at 22°C in white light under a 16-h photoperiod. Pycnidia were produced on stem fragments and contained alpha and beta conidia typical of the genus Diaporthe (2). Alternatively, pycnidia were also obtained on malt agar medium after 2 weeks of culture at 25°C in white light under a 12-h photoperiod. The size of alpha and beta conidia was 6.3 ± 0.5 × 2.3 ± 0.4 μm and 23.3 ± 1.8 × 0.9 ± 0.2 μm, respectively (n = 170). In order to confirm the identification at the genus level and determine the species, DNA was extracted from the mycelium of three representative isolates and the ITS regions of the ribosomal DNA were amplified using universal primers (1). The sequences of the amplified products (GenBank Accession Nos. KF240772 to KF240774) were 100% identical with the ITS sequence of a Diaporthe angelicae isolate deposited in the NCBI database (CBS 111592 isolate, KC343027). To confirm pathogenicity, the three isolates of D. angelicae were inoculated on carrot umbels in the greenhouse. A total of nine plants were inoculated (three plants per isolate). Using a micropipette, 10 μl of a conidial suspension containing alpha and beta conidia (105 conidia mL–1) were deposited at the base of the primary umbel and two secondary umbels, which were wounded before inoculation using a scalpel blade. Seven inoculated plants developed triangular, necrotic lesions that were typical umbel browning. D. angelicae was re-isolated on malt agar medium from the inoculated diseased carrot umbels. To our knowledge, this is the first report of D. angelicae in carrot cultivated for seed production in France. The disease resembles the lesions described in the Netherlands in 1951 on carrot inflorescence caused by Phomopsis dauci (3). In future experiments, it would be crucial to precisely determine if D. angelicae could be transmitted to the seeds. References: (1) M. A. Innis et al. PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA, 1990. (2) J. M. Santos and A. J. L. Philips. Fungal Divers. 34:111, 2009. (3) J. A. von Arx. Eur. J. Plant Pathol. 57:44, 1951.

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