Greenhouse-grown Cucumber Research Articles

First Report of Cucumber vein yellowing virus on Cucumber in Lebanon.

In a 2-year (2008 to 2009) wide-scale survey of viruses infecting cucurbits, a limited number of greenhouse-grown cucumber (Cucumis sativus) plants showed vein-yellowing symptoms. Greenhouses were infested with whiteflies and infection with Cucumber vein yellowing virus (CVYV) was suspected. CVYV is widely distributed in southern Europe in both open field and protected cucurbit crops (2). Total RNA was extracted from seven plants with vein yellowing symptoms using TRI Reagent (Sigma-Aldrich, St Louis, MO). RT-PCR tests using CVYV-specific primers (CV+/CV-) targeting the coat protein of CVYV (2) gave amplicons of the expected size from seven plants. The sequence of one representative isolate, CVYV-LB3 (GenBank Accession No. JF289167), showed 97, 95.6, and 95.2% pairwise nucleotide identity with isolates from Tunisia (EF538680), Israel (AF233429), and Jordan (JF460793), respectively. In 2012, CVYV like symptoms were not observed in greenhouses in the same areas. In early spring 2013, a total of 16 leaf samples with vein-yellowing symptoms were collected from the northern coastal areas (Jbeil, Amshit, Tabarja) and 11 samples showing only yellowing on older leaves from the southern coast (Jiyeh). CVYV was detected in all samples from the northern coast and in four samples from the southern coast. Four isolates from the North and two from the South were sequenced (KC990497 to KC990502) and showed high sequence variation. The pairwise nucleotide and amino acid identities between these isolates ranged from 95.1 to 100% and 98.5 to 100%, respectively. Pairwise nucleotide and amino acid identities of the isolates with CVYV-LB3 showed variable homology between 93.7 to 98.2% and 94.6 to 96.6%, respectively. The inter-population structure of CVYV in Lebanon showed high variability as compared to the homogenous Spanish population (4). For transmission tests, non-viruliferous whiteflies (Bemisia tabaci) were exposed for an 18-h acquisition access period on vein-yellowed leaves followed by a 24-h inoculation access period to healthy cucumber plants (5-leaf stage). In addition, leaves with vein-yellowing symptoms were ground in 0.1 M phosphate buffer (pH 7.0) and sap-inoculated on carborundum-dusted cucumber (cv. Delta) and squash (Cucurbita pepo cv. FarajF1) plants. Vein yellowing symptoms developed 9 to 11 days post-inoculation on all whitefly inoculated plants, while symptoms were delayed till 3 weeks post inoculation on seven out of eight sap-inoculated plants. All symptomatic plants were positive for CVYV by RT-PCR. Furthermore, surveyed plants were also tested for Cucurbit chlorotic yellows virus (CCYV) and Cucurbit yellow stunting disorder virus (CYSDV), two criniviruses reported previously in Lebanon, by RT-PCR (1). Double or triple infection of CCYV and CYSDV occurred in 18 out of 20 of the CVYV-infected plants. During the past 5 years, a limited number of cucumber plants showed CVYV symptoms. This indicates that CVYV occurrence is sporadic. However, its occurrence in mixed infection with criniviruses may have damaging economic implications to cucurbit production (3). To our knowledge, this is the first report of CVYV on cucurbits in Lebanon and its occurrence in co-infection with CCYV.

품종별, 생육단계별 시설재배 오이의 페놀화합물 함량과 항균효과 및 Tyrosinase 억제활성

시설오이로 많이 재배되고 있는 4 품종을 선발하여 생육단계별로 총 페놀 및 플라보노이드 함량, 피부염증과 가려움증 관련 Staphylococcus aureus, Staphylococcus epidermidis, Malassezia furfur균에 대한 항균효과 그리고 tyrosinase 억제 활성에 대하여 비교 분석하였다. 총 페놀 함량은 장죽청장과 장형낙합 품종에서 늘푸른청장과 신조은백다다기 품종에 비해 상대적으로 다소 높게 나타났으며, 생육단계별로는 대부분 수확기에 이른 5단계에서 높은 함량을 보였다. 총 플라보노이드 함량은 조사된 오이 4품종 모두 생육단계별로 큰 차이를 나타내지는 않았다. 항균활성은 Staphylococcus aureus균에서는 장형낙합 품종이 모든 생육단계에서 상대적으로 높은 활성을 보였으며, Staphylococcus epidermidis균에서는 생육단계 및 품종에 따라 저해환이 8~12 mm로 항균성에 차이를 나타냈다. 또한 Malassezia furfur균에서는 장죽청장에서 항균활성이 높게 나타났으며, 특히 생육 3, 4단계에서는 저해환이 14 mm로 형성되어 가장 높은 항균효과를 보였다. 전체적으로 오이의 항균성은 Staphylococcus aureus균에서 비교적 높은 것을 확인할 수 있었다. 오이 추출물의 tyrosinase 억제 활성은 장축청장과 신조은백다다기 품종에서 상대적으로 높은 활성을 보였으며, 다음으로 장형낙합 품종에서 비교적 높게 나타났지만, 늘푸른청장의 경우는 상대적으로 낮은 활성을 보였다. 또한 생육초기보다 수확기에 이르렀을 때 모든 품종에서 tyrosinase 억제 활성이 다소 높게 나타났다. 본 실험의 결과, 피부상재균 및 비듬균에 대한 오이의 항균성과 미백효능을 확인함으로서 향후 고부가가치 향장소재로서의 이용성을 더욱 증대시킬 수 있을 것으로 기대된다. The contents of total phenolics and flavonoids, antimicrobial and tyrosinase inhibition activities of five growth stages with four greenhouse-grown cucumber extracts were investigated. Total phenolic content was high in Jangjukcheongjang, Janghyeongnakhap and five growth stage(24~27 cm). The content of total flavonoid did not differ between cultivar or growth stages. Among the four cucumber cultivars, the extract of Janghyeongnakhap showed a relatively strong antimicrobial effect against Staphylococcus aureus. The inhibition zone against Staphylococcus epidermidis of the samples tested in this experiment was 8~12 mm. And the antimicrobial effects against Malassezia furfur was high in Jangjukcheongjang, and showed the highest by the inhibition zone of 14mm in three(17~20 cm) growth stage. The tyrosinase inhibition activity of cucumber extracts showed relatively high activity in Jangjukcheongjang and Sinjoeunbaekdadagi, followed by Janghyeongnakhap. From these results, we confirmed that the extract of cucumber has high antimicrobial and whitening efficacy, and that in the future, the cucumber will be increase the availability in the field of high-value cosmetic materials.

Effect of PGPR on population growth parameters of cotton aphid

Plant-growth-promoting rhizobacteria (PGPR) help plants by increasing plant growth and defending them against pathogens and pests. There is considerable research supporting the use of these bacteria in plant pathogens management, but the number of research papers that have focused on their effect on insect pests control is quite few. In this research, we examined the ability of four native strains of Pseudomonas fluorescens to manage the cotton aphid, Aphis gossypii, on greenhouse-grown cucumbers in Iran. The strains UTPF (University of Tehran Pseudomonas fluorescens) 68, UTPF1, UTPF6 and PF169 of P. fluorescens were used as seed treatment to evaluate their impact on both cucumber growth and cotton aphid population growth parameters. The strains UTPF68 and PF169 of this bacterium influenced phenology of cucumber by decreasing the Growing Degree Days of flowering period. Also, the plants treated with these bacterial strains had a significant increase in yield weight of approximately 58%. In the other part of the study, various effects on developmental parameters of aphid were recorded among bacterial strains, but only PF169 caused significant decreasing effect on rm value of aphid, which is the most important factor in aphid’s life table. We conclude that the PF169 treatment had significant negative effects on population growth rate of A. gossypii. The PF169 could be reliable in a control programme for A. gossypii on cucumber plants in greenhouses.

First Report of Cucurbit chlorotic yellows virus Infecting Cucumber, Melon, and Squash in Iran.

Yellowing diseases of field- and greenhouse-grown cucurbits are becoming increasingly important in many cucurbit cultivation areas in Iran. Virus surveys were conducted from 2011 to 2012 in greenhouse-grown cucumber (Cucumis sativus L.) and field-cultivated cucumber, squash (Cucurbita sp.) and melon (Cucumis melo L.) in Tehran, Semnan, Bushehr, Hormozgan, Isfahan, Yazd, and Fars provinces, the major cucurbit-growing areas in Iran. Leaf samples with various symptoms, e.g., chlorosis, interveinal chlorotic spots on lower leaves, bright yellow color or sever yellowing on older leaves, were collected and screened for the presence of the whitefly transmitted criniviruses (family Closteroviridae) Cucurbit chlorotic yellows virus (CCYV) and Cucurbit yellow stunting disorder virus (CYSDV) through double-antibody sandwich (DAS)-ELISA, using CCYV and CYSDV specific antisera (DSMZ, Germany). The ELISA results showed that of 347 cucumber leaf samples originating from cucumber greenhouses, 170 and 65 were positive for CCYV and CYSDV, respectively, and 45 samples were infected with both viruses. In addition, of 147 leaf samples collected from melon, cucumber, and squash grown in open fields, 57 and 53 were infected with CCYV and CYSDV, respectively, and 14 were infected with both viruses. These results indicate that these two viruses are widely distributed on these cucurbit crops in Iran. CCYV was not detected in Bushehr and CYSDV was not detected in Isfahan and Hormozgan provinces. To confirm the presence of CCYV and CYSDV, total RNA was extracted (Sigma Chemical, St. Louis, MO) from 18 samples that reacted positive in DAS-ELISA originating from different surveyed provinces. RT-PCR was carried out using specific primers Crini-s2 (5'-CATTCCTACCTGTTTAGCCA-3') (2) and Crini-as1 (5'-ATCCTTCGCAGTGAAAAACC-3') to amplify a 460-bp fragment of the HSP70 gene and CCYV using specific primers CCYV-HSP-F1 (5'-TGCGTATGTCAATGGTGTTATG-3') and CCYV-HSP-R1 (5'-ATCCTTCGCAGTGAAAAACC-3') to amplify a 462-bp fragment of the HSP70 gene (latter 3 primers from [3]). Expected DNA fragments for CYSDV and CCYV were amplified from 11 (CCYV 7/11, CYSDV 4/11) of 18 samples but not from any of the healthy controls. Further analysis by sequencing three selected PCR products amplified with primers CCYV-HSP-F1/R1 showed complete consensus among the sequences, and in comparison with sequences available at GenBank, the highest identities were obtained to Asian CCYV isolates (94% nt/98% aa identity). The CCYV sequences were deposited in GenBank under accessions KC559449 to KC559451. The identity of the amplified CYSDV DNA could also be confirmed by sequencing of three PCR products. CCYV has first been proven to occur in different countries in East Asia and has recently been reported from Sudan (2) and Lebanon (1), indicating the putative spread of the virus wherever cucurbits are grown and its vector, the whitefly Bemisia tabaci, is present. Large populations of whiteflies were present in all surveyed areas. However, to our knowledge, this is the first report for the occurrence of CCYV in Iran. In conclusion, the presence of CCYV and CYSDV in the major cucurbit growing provinces and the large whitefly population pose a serious threat to cucurbit production in Iran.

Fungal species that cause powdery mildew in greenhouse-grown cucumber and melon in Paraná State, Brazil

The powdery mildew caused by Oidium spp. is an important disease for several crops of the Cucurbitaceae family. Although the teleomorphs, Podosphaera xanthii and Golovinomyces cichoracearum, currently have already been described as the causal agents of powdery mildew in Brazil, only P. xanthii is considered the main causal agent of powdery mildew field epidemics. The objective of this work was to identify and determine the prevalence of the species causing powdery mildew in cucumber (Cucumis sativus) and melon (Cucumis melo var. reticulatus) grown in greenhouses in the State of Paraná in Brazil. The morphological traits of the conidial stages, such as the presence of fibrosin bodies and a germinative tube, were used to identify the species. Leaves exhibiting high severity of powdery mildew were collected from plants of 13 plastic greenhouses during different seasons in 2003/2004 and in different regions of Paraná State. In all environments, a significant prevalence of P. xanthii (80-100%) was observed affecting parthenocarpic or ordinary cucumber and melon. Golovinomyces cichoracearum was observed in six greenhouses, with up to 20% of conidia of this species on the samples.

Mineral and Ascorbic Acid Concentrations of Greenhouse- and Field-Grown Vegetables: Implications for Human Health

Vegetable nutritional quality is related to concentrations of antioxidants and other phytonutrients. In Iran, vegetables can be produced in soil in climate-controlled greenhouses. Limited information is available on the quality of greenhouse-grown vegetables compared to field-grown vegetables. Concentrations of Ca, Mg, P, K, Fe, Zn, Cu, Mn, and ascorbic acid in greenhouse- and field-grown bell pepper (Capsicum annuum L.), cucumber (Cucumis sativa L.), and tomato (Solanum lycopersicum L.) were determined. Mean fruit K, P, and Mg concentrations in greenhouse-grown bell pepper, cucumber, and tomato were greater than expected levels. Mean fruit K concentrations in greenhouse-grown bell pepper, cucumber, and tomato were lower than that in field-grown vegetables. Greenhouse-grown vegetables accumulated greater amounts of P in fruit compared to field-grown vegetables. More than 48%, 38%, 30%, and 54% of greenhouse vegetables were Fe, Zn, Cu, and Mn deficient, respectively. Field-grown vegetables had lower contents of Cu, Mn, Fe, Zn, and ascorbic acid compared to greenhouse-grown vegetables. Calcium, Fe, Cu, Mn, and Zn intakes through consumption of greenhouse-grown vegetables for population study groups accounted for a negligible fraction of the recommended daily allowance (RDA), whereas daily intake of ascorbic acid was greater than the RDA requirement. Intake of micronutrients and ascorbic acid from field-grown vegetables was less than that from greenhouse-grown vegetables. In general, the nutritional quality (contents of micronutrients and ascorbic acid) of greenhouse-grown vegetables was better than that of field-grown vegetables, although fruit micronutrient concentrations of field- and greenhouse-grown vegetables were lower than expected levels. The results indicated that bell pepper is an excellent source of ascorbic acid and potassium for humans. Despite a protected system of cultivation, poor fertilizer management in greenhouses could adversely affect the nutritional value of vegetables. Improved nutritional management in greenhouses could enhance micronutrient concentrations in these vegetables.

Root Characteristics and Yield of Greenhouse-Grown Cucumber in Continuously Cropped Soil

The cucumber (Cucumis sativus L.) production in greenhouse-grown reacted an important on vegetable supply. An experiment was conducted, during the 2001-2002 and 2002-2003 cropping seasons, November 2001 to the early July 2002 in the first season, and October 2002 to early July 2003 in the second season, in a solar greenhouse on the Loess Plateau in Yan’an, Shaanxi, Northwest China, to study the root characteristics, growth and fruit yield of cucumber as affected by growing in soils that have been continuously cropped cucumbers for 0, 1, 4, and 8 years. The results showed that the number of cucumber roots, root length, root dry weight, plant height, and leaf number decreased, but root diameter increased as the duration of continuous cropping increased. The fresh fruit productivity was the highest on the soil with 1year cropping history and decreased as the duration of continuous cropping increased to 4 years or more. Root number, root length, and root weight were correlated positively with yield whereas root diameter was correlated negatively with yield. The results emphasized the point that 4 years duration of continuous cropping is an important warning time for greenhouse cucumber production. If the duration of continuous cropping was beyond 4 years, poor root growth and decrease in yield of the cucumber would start appearing. In order to promote root development and increase fruit productivity, beyond 4 years of continuous cropping should be avoided in cucumber production management.

First report of Fusarium oxysporum f. sp. radicis‐cucumerinum on cucumbers in Turkey

During spring in the years 2007, 2008 and 2009, a root and stem rot disease was observed on greenhouse-grown cucumber plants (Cucumis sativus) in the Kumluca district of Antalya, Turkey. In 2009, about 10% of plants were lost due to the disease. The symptoms were severe wilting of the above ground parts associated with yellowing and drying of the lower leaves. A yellowish brown discolouration of the vascular tissues and rotting of the roots and stem were also observed. A fungus was isolated from the discolored vascular tissue of the lower plant stems on potato dextrose agar (PDA). The fungus produced salmon-pink colonies on PDA and light colored colonies on sucrose nutrient agar. On both media orange sporodochia formed. The fungus produced abundant microconidia in false heads on simple phialides (5·00–10·75 × 1·75–3·25 μm). Typical macroconidia were mostly three-septate (31·25–42·50 × 3·00–4·50 μm). Chlamydospores were observed. Based on the morphological characteristics, the fungus was identified as Fusarium oxysporum. Pathogenicity tests were conducted on Cucumis sativus, Luffa acutangula, L. aegyptiaca, Cucurbita maxima × C. moschata, Cucurbita ficifolia, Cucumis melo and Citrullus lanatus plants. An isolate of the fungus was grown on PDA at 23°C for 7 days, with a 12 h photoperiod under fluorescent lamps. The seedlings at the first true leaf stage were inoculated by dipping the roots in a spore suspension produced from PDA cultures (3 × 106 spores per mL) for 10 min. The plants were kept in a growth chamber at 25°C with a 12 h photoperiod. Control plants were treated with sterile distilled water using the same technique. Three weeks after inoculation, cucumber plants presented severe root and stem rot symptoms and died. Luffa aegyptiaca, Cucumis melo and Citrullus lanatus plants showed the same symptoms, whereas Luffa acutangula and Cucurbita species were healthy. Fusarium oxysporum was reisolated from diseased plants to fulfil Koch’s postulates. Two formae speciales of F. oxysporum infect cucumber; f. sp. cucumerinum causes vascular wilting, whereas f. sp. radicis-cucumerinum causes wilting accompanied by root and stem rot. In addition to cucumber, the latter fungus can also infect melon (Cucumis melo), watermelon (Citrullus lanatus) and sponge gourd (Luffa aegyptiaca). Based on the disease symptoms on cucumber plants and differing pathogenicity on different plant species of the Cucurbitaceae, this fungus was identified as F. oxysporum f. sp. radicis-cucumerinum (Vakalounakis, 1996; Punja & Parker, 2000). Wilt disease of cucumber caused by F. oxysporum f. sp. cucumerinum has been recorded in Turkey for a long time (Yıldız & Delen, 1977), but this is the first report of F. oxysporum f. sp. radicis-cucumerinum in this country.

Suppression by Red Light Irradiation of Corynespora Leaf Spot of Cucumber Caused byCorynespora cassiicola

The effect of red light irradiation on development of Corynespora leaf spot of cucumber plants (Cucumis sativus L. cv. Hokushin) caused by Corynespora cassiicola (Berk. & Court.) was investigated in greenhouses. In a greenhouse without red light (―Red), lesions enlarged, coalesced, and finally covered the entire leaves of cucumber. In a greenhouse with red light (+Red), however, lesion appearance was delayed relative to that under ―Red and its development was also significantly suppressed. Such difference in disease development was also observed in cucumbers grown under +Red and ―Red in the same greenhouse. Disease suppression under red light was also observed in glasshouse-grown C. cassiicola-inoculated cucumbers. Red light did not inhibit the infection behaviour of the pathogen. Our results indicated that the delay and suppression of Corynespora leaf spot of cucumber under + Red were due to induction of resistance in cucumber, and not to differences in environmental conditions or fungal population between the two greenhouses. Red light-induced resistance might contribute to the development of new methods for controlling Corynespora leaf spot of greenhouse-grown cucumber.

Application of a sorting procedure to greenhouse-grown cucumbers and tomatoes

Sorting method, a simple procedure to evaluate sensory differences in cucumbers and tomatoes, requiring minimal training and labour, was applied to cucumbers and tomatoes grown under natural and artificial light in Finland and natural light in Spain, and evaluated after set storage times of up to 22d. Descriptive sensory profiling was also performed on the same samples. Sorting data were analysed using multidimensional scaling (MDS), while principal component analysis (PCA) was used to interpret profiling data. For both cucumbers and tomatoes, similar trends were observed by use of either sorting or descriptive sensory analysis. Differences between sources and storage times were found for all samples at all sampling times. Natural light-grown cucumbers were rated higher for odour and taste intensity than those grown in artificial light. Both consistency and intensity of red colour contributed significantly to differences between Finnish and Spanish tomatoes. Sorting was less time consuming and labour demanding, yet it resulted in the positioning of samples equivalent to the more complex profiling method. Thus, sorting appears to be a viable alternative to profiling when sensory similarities and differences, rather than accurate sensory profiles, are required.

Isolation and characterization of <i>tobacco necrosis virus</i> detected on some vegetable species

* Corresponding author. E-mail: irena.zitikaite@botanika.lt A virus disease agent was isolated from greenhouse-grown cucumber (Cucumis sativus L.), field-grown common bean (Phaseolus vulgaris L.) and white cabbage (Brassica oleracea var. capitata (L.) Alef) crops in Lithuania. The diseased vegetable plants expressed various spotting or mottling symptoms on leaves or fruits and necrotic symptoms on older leaves. The objective of this study was to identify the causal agent of the virus-like disease of these plant species. For the identification of the causal virus, the infection from cucumber, common bean and white cabbage leaves or fruits was transmitted to main test plant species which reacted by only local lesions. In electron microscopic preparations from infected plants, only icosahedral virus particles about 26 nm in diameter were detected. According to particle morphology, host range and symptoms, the causal virus was identified as tobacco necrosis virus (TNV). This finding was supported by the reverse transcription–polymerase chain reaction (RT–PCR) technique which confirmed that the virus isolates from the Lithuanian cucumber, common bean and white cabbage crops were identical with the TNV strain A “Nebraska” isolate.

Functional–structural plant modelling in crop production. Wageningen UR Frontis Series, vol. 22

Functional–structural plant modelling in crop production. Wageningen UR Frontis Series, vol. 22

First Report of Alternaria alternata f. sp. cucurbitae Causing Alternaria Leaf Spot of Melon in the Mid-Atlantic Region of the United States.

Alternaria alternata f. sp. cucurbitae, the casual agent of Alternaria leaf spot, was first described in Greece where it caused severe losses to greenhouse-grown cucumbers (Cucumis sativus) (3,4). The fungus also attacks melon (C. melo) and watermelon (Citrullus lanatus) (1-3). In late June of 2006, following a period of windy and rainy days, numerous dark brown, circular lesions, 0.5 to 1 mm in diameter, were observed on leaves of melons in a field in Wicomico County, Maryland. The lesions gradually enlarged and coalesced into large, nearly circular, or irregularly shaped lesions that could be as long as 3 cm. The center of the lesions was light tan, surrounded by a dark brown ring and a chlorotic halo, and tended to split in the later development stages. Most of the lesions appeared on the edge of the leaves and no lesions developed on the stems and fruit. Lesions first started on old leaves and then developed on leaves in the middle part of the canopy. Leaf lesions were observed on melon cvs. Ananas, Honeydew Greenflesh, and Israeli. Disease severity ranged from 3 to 20% of the leaf area affected. Small pieces (3 × 3 mm) of tissue removed from the margin between healthy and diseased tissue were surface disinfected in 0.5% NaOCl for 2 min and plated on acidified, ¼-strength potato dextrose agar. Isolations made from diseased tissue frequently (61%) yielded fungal colonies with morphological features and spore dimensions that were consistent with the description of A. alternata f. sp. cucurbitae (1,3). Fungal isolates were characterized by small, short-beaked, multicellular conidia. Conidia were ovoid, obclavate, and sometimes ellipsoidal with the average overall body length of 39 μm (range, 17 to 80 μm) and width of 14 μm (range, 7 to 20 μm). Conidia were produced on short conidiophores in chains. The beaks were short (often less than one-third the body length) and conical or cylindrical. Pathogenicity of six single-spore isolates was determined on four melon cultivars (Honeydew Greenflesh, Israeli, Tam Dew, and Topmark) and one watermelon cultivar (Sugar Baby) in a greenhouse. Twenty plants of each cultivar at the one-true-leaf stage were sprayed with a conidial suspension (106 conidia/ml) of each isolate amended with 0.1% (vol/vol) of Tween 20 until runoff (1.5 to 2 ml per plant). Inoculation with sterile distilled water amended with 0.1% Tween 20 served as controls. The plants were placed in a dew growth chamber for 48 h at 24°C and subsequently maintained in a greenhouse at 21 to 29°C. At 4 to 5 days after inoculation, each isolate induced leaf lesions on each inoculated cultivar similar to typical lesions observed in the field. There was no significant difference in disease severity among the cultivars tested or between melon and watermelon. Control plants remained symptomless. The fungus was readily reisolated from symptomatic tissues. To our knowledge, this is the first report of A. alternata f. sp. cucurbitae causing Alternaria leaf spot of melon in the Mid-Atlantic United States and the only report outside Georgia in the southern region of the United States (D. B. Langston, personal communication) and Greece.

Molecular and Serological Characterization of Cucumber mottle virus, a New Cucurbit-Infecting Tobamo-like Virus.

A new tobamo-like virus was isolated from a greenhouse-grown cucumber that showed severe mosaic distortion on leaves and fruit, in the southern part of Japan. The virus was tentatively designated Cucumber mottle virus (CuMoV) and further characterized. The size and antigenicity of the coat protein (CP) and the complete sequence of the genome were compared with those of the known cucurbit-infecting tobamoviruses: the W and SH strains of Cucumber green mottle mosaic virus (CGMMV), the C and Y strains of Kyuri green mottle mosaic virus (KGMMV), Cucumber fruit mottle mosaic virus (CFMMV), and Zucchini green mottle mosaic virus (ZGMMV). The CP of CuMoV migrated more slowly than those of CGMMV-W and -SH and KGMMV-C and -Y in sodium dodecyl sulfate polyacrylamide gel electrophoresis. In Western blot analysis, the CP of CuMoV cross-reacted weakly with antisera against CGMMV-W and did not react with antisera against KGMMV-Y. The overall nucleotide sequence of CuMoV had 62.5 to 63.5% identity with those of CGMMV-W, -SH, KGMMV-Y, CFMMV, and ZGMMV. The genome organization was characteristic of tobamoviruses, encoding a 131-kb protein, a 188-kb protein, a movement protein (MP), and CP in 5' to 3' order. In the phylogenetic analyses of the CP, CuMoV was placed in a separate lineage from CGMMV-W, -SH, KGMMV-C, -Y, CFMMV, and ZGMMV. The results indicate that CuMoV is a distinct tobamovirus species which represents a third sub-subgroup in the cucurbit-infecting tobamoviruses.

Within-Plant Distribution of <I>Bemisia tabaci</I> (Homoptera: Aleyrodidae) Adults and Immatures on Greenhouse-Grown Winter Cucumber Plants

Within-plant distribution of adults, pupae, nymphs, and eggs of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) on leaves of greenhouse-grown winter cucumber, Cucumis sativum L., plants were studied in field plots for integrated pest management decision making. Distribution of specific life stages depended on the leaf positions. The leaves with most abundance and low or lowest variation of whiteflies were leaves 8-12 for adults, 8-11 for pupae, 6-12 for nymphs, and 6-9 for eggs. In light of the criterion in selecting within-plant sample sites with pest abundance and low variation, these leaves were considered as the most convenient for sampling specific life stages of B. tabaci. Single a and b values for each life stage of the whitefly were calculated by Taylor's power law and were used to estimate minimum sample sizes at a precision of 0.25 (SE/mean). The minimum sample size decreased with increasing density of adults on leaves 8-12, of nymphs on leaves 7 and 8, and of eggs on leaf 6, but slightly increased with increasing density of pupae on leaves 8-11, of nymphs on leaves 6 and 9-12, and of eggs on leaves 7-9.

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Abstracts of Nippon Dojo-Hiryogaku Zasshi

Suppression of damping-off of cucumber caused by Pythium ultimum with live cells and extracts of Serratia marcescens N4-5

Environmentally friendly control measures are needed for the soil-borne pathogen, Pythium ultimum. This pathogen can cause severe losses to field- and greenhouse-grown cucumber and other cucurbits. Live cells and ethanol extracts of cultures of the bacterium Serratia marcescens N4-5 provided significant suppression of damping-off of cucumber caused by P. ultimum when applied as a seed treatment. Live cells of this bacterium also suppressed damping-off caused by P. ultimum on cantaloupe, muskmelon, and pumpkin. Culture filtrates from strain N4-5 contained chitinase and protease activities while ethanol extracts contained the antibiotic prodigiosin, the surfactant serrawettin W1, and possibly other unidentified surfactants. Production of prodigiosin and serrawettin W1 was temperature-dependent, both compounds being detected in extracts from N4-5 grown at 28 °C but not in extracts from N4-5 grown at 37 °C. Ethanol extracts from strain N4-5 grown at 28 °C inhibited germination of sporangia and mycelial growth by P. ultimum in in vitro experiments. There was no in vitro inhibition of P. ultimum associated with ethanol extracts of strain N4-5 grown at 37 °C. Prodigiosin, purified from two consecutive thin-layer chromatography runs using different solvent systems, inhibited germination of sporangia and mycelial growth of P. ultimum. Another unidentified compound(s) also inhibited germination of sporangia but did not inhibit mycelial growth. There was no in vitro inhibition associated with serrawettin W1. These results demonstrate that live cells and cell-free extracts of S. marcescens N4-5 are effective for suppression of damping-off of cucumber caused by P. ultimum possibly due in part to the production of the antibiotic prodigiosin.

Effect of Zinc and Copper on Physiological Disorder in Green-House Grown Cucumber

Effect of Zinc and Copper on Physiological Disorder in Green-House Grown Cucumber

Characterisation of cucumber leaf spot virus isolated from recycled irrigation water of soil-less cucumber cultures

Greenhouse-grown cucumber plants showed mosaic-type symptoms and irregular yellow spots on their leaves. The disease did not affect plant growth and the fruits remained symptom free. A virus having isometric particles, 30 nm in size, was isolated from the infected tissues and from recycled drainage water collected from tuff (volcanic rock) raised beds on which plants were grown. The virus was identified as a variant of cucumber leaf spot virus (CLSV) that has a host range similar but not identical to that of a previously described CLSV isolate. The overall nucleotide sequence identity between the RNAs of the Israeli isolate and the type isolate virus (accession numbers: DQ227315 and AY571334, respectively) amounts to 96%.

Effects of Different Nitrogen Rates on Yield and Leaf Nutrient Contents of Drip-fertigated and Greenhouse-grown Cucumber

Effects of Different Nitrogen Rates on Yield and Leaf Nutrient Contents of Drip-fertigated and Greenhouse-grown Cucumber