Slicing Cucumber Research Articles

Economic impacts of reduced fungicide efficacy against downy mildew on slicing cucumber

Fungicides remain the most important tool to manage downy mildew on cucumber. The objective of this study was to estimate yield losses that might occur if fungicides to which Pseudoperonospora cubensis has demonstrated reduced efficacy were applied to slicing cucumber. A downy mildew-susceptible hybrid cultivar was grown in spring and fall 2020, sprayed weekly with one of four oomycete-specific fungicides (cymoxanil, fluopicolide, propamocarb, or oxathiapiprolin + chlorothalonil) applied in alternation with chlorothalonil. Control treatments were chlorothalonil applied biweekly and water. The fluopicolide-chlorothalonil treatment and the water control were repeated in spring 2021. Cucumbers were harvested 12 times, sorted by size, and weighed. Profits were calculated by subtracting production and fungicide application costs from the crop values, which were calculated with prices from terminal markets in the eastern United States during the harvest periods. Treatments performed the same in spring and fall 2020. Area under the disease progress curve (AUDPC) was significantly lower with fluopicolide, propamocarb, and oxathiapiprolin + chlorothalonil than cymoxanil and both controls (P = 0.01). AUDPC was lower with fluopicolide than with oxathiapiprolin + chlorothalonil. Mean marketable weights did not differ among the four fungicide treatments but were greater than in the two control treatments (P = 0.05). Profits also were greater for the four fungicide treatments than the controls, a mean of $8,829/ha versus $2,437/ha, respectively. Results with fluopicolide-chlorothalonil in 2021 confirmed results in 2020. Fungicides with reduced efficacy, like cymoxanil, or fungicides for which resistance has been reported, like propamocarb hydrochloride or fluopicolide, may still protect hybrid slicing cucumber from yield losses due to downy mildew.

Combined Influence of Grafting and Type of Protected Environment Structure on Agronomic and Physiological Traits of Single- and Cluster-Fruit-Bearing Cucumber Hybrids

Protected vegetable cultivation is a fast-growing sector in which grafting plays a crucial role for success. Cucumber is predominantly grown under protected conditions. The popular slicing (mini) cucumber comprises two segments, single- and cluster-fruit-bearing. In the present study, the performance of select fruit-bearing hybrids grafted as scions onto commercial Cucurbita hybrid rootstock ‘NS-55’ was evaluated under three different low-cost protected structures in arid regions. With respect to type of protected structure, cucumber performance was superior under a naturally ventilated polyhouse (NVP) than an insect net house (INH) or a shade net house (SNH). Micro-climate parameters inside NVP (air temperature, RH and PAR) were more congenial for cucumber than those in net houses, thereby facilitating improved physiology (chlorophyll fluorescence, chlorophyll and plant water potential) and leaf mineral status. Grafting invariably improved growth and yield parameters under all protected structures. Overall plant performance was better in the grafted cluster-fruit-bearing hybrid ‘Terminator’ than the single-fruit-bearing hybrid ‘Nefer’ or their non-grafted counterparts. Furthermore, NVP was found to be superior to net houses for water productivity, and grafted plants were more water use efficient than their counterpart non-grafted plants. Thus, NVP can be considered a suitable low-cost protected structure in conjunction with grafting to boost cucumber crop and water productivity in arid regions.

Deriving tropical gynoecious inbred backcross lines from exotic pickling cucumber using marker assisted backcross breeding

Indian cucumber cultivars are basically monoecious and vigorous in nature with many lateral branches but they are poor in productivity. The present study was aimed to introgress gynoecious trait (F locus) from pickling cucumber line (Gy14) into elite Indian cultivar Pusa Uday using marker assisted backcross breeding. Based on allelic diversity analysis, the allele numbers per locus ranged from 2 to 3 in BC1F3 and the observed heterozygosity (Ho) was ranged from 0.01 to 0.55. The heterozygosity expected (He) mean was 0.28 (range 0.03 to 0.50) which was higher than mean Ho (0.18) and mean polymorphic information content (PIC) for 87 markers was 0.23. Whereas the allele numbers per locus was 2 in BC2F2 and the observed heterozygosity (Ho) was ranged from 0.01 to 0.56. The mean expected heterozygosity (He) was 0.24 which was higher than mean Ho (0.17) and the mean PIC value was 0.19. The gynoecism (F locus) was introgressed in the Indian slicing cucumber cv. Pusa Uday though backcross breeding accompanied by foreground and background selections. The foreground selection was performed with one dominant SCAR marker, and 3 SSR markers (SSR 00233, SSR 15516 and SSR13251). A total of 87 polymorphic markers spanning genetic distance of 1031 cM with an average distance of 12.9 cM between adjacent markers were used for background selection. The genome recovery of the individuals in BC1F3 population was ranged from 62.64% to 93.10% while among BC2F2 plants it was ranged from 89.66% to 95.40%. Four inbred backcross lines (IBL) were selected from backcross populations (BC1F4 and BC2F3) those were purely gynoecious even at 45°C with more than 5 lateral branches. Hence, marker assisted backcross breeding served as a potential approach for precise introgression of the gynoecy (F locus) from picking cucumber to Indian slicing cucumber.

Integrated Management of Downy Mildew on Slicing Cucumber With Fungicides and Host Resistance But Not Trellising.

The objective of this study was to evaluate fungicide applications, host resistance, and trellising, alone and in combination, as management practices for downy mildew on slicing cucumber. A split-split plot experimental design was used with three and four replications in spring and fall 2017, respectively. The whole-plot treatment was fungicide, four applications of chlorothalonil (Bravo Weather Stik 6SC) alternated with three applications of cyazofamid (Ranman 400SC), or water. Split plots were nontrellised or trellised with four strings supported by stakes. Split-split plots were cultivar Bristol, which is intermediately resistant to downy mildew, or cultivar Speedway, which is susceptible to downy mildew with similar parentage as Bristol. In both seasons, area under the disease progress curve (AUDPC) values were lower with fungicides than water for both cultivars. In the spring, AUDPC for Bristol was lower than for Speedway regardless of fungicide treatment. In the fall, Bristol had a lower AUDPC than Speedway with fungicides, but the AUDPC did not differ between the two cultivars with water. The mean AUDPC for trellised plants (376.2) was lower than for nontrellised plants (434.0; P = 0.007). Fungicide applications increased marketable and total fruit weights in both seasons (P ≤ 0.0002). Marketable weight with fungicides was almost double (93% greater) the marketable weight with water. Marketable weight was 55% greater for Bristol than for Speedway in spring, but yields did not differ between cultivars in fall (season-by-cultivar interaction, P ≤ 0.0003). Because trellising had no effect on marketable yields (P = 0.11), trellising is not recommended for managing downy mildew on slicing cucumber. Of the three management techniques examined, fungicides had the largest effects on disease and yields, followed by cultivar resistance.

Investigation of plant sources of hydroperoxide lyase for 2(E)-hexenal production

Abstract 2(E)-hexenal is a green note flavour molecule that is widely used in various compositions of aromas, flavours and perfumery. As there is considerable demand for naturally produced aromas this article deals with some aspects of this C6-volatile production with regard to the selection of plant source material and reaction conditions. The following plants were tested for this purpose: runner bean (Phaseolus coccineus), common bean (Phaseolus vulgaris), three (Capsicum annuum) bell pepper varieties, garden cress (Lepidium sativum), green slicing cucumber (Cucumis sativa), mung beans (Vigna mungo) and brown lentils (Lens culinaris). Selection of source material was considered on the basis of 2(E)-hexenal yield and productivity. The common bean leafs were able to produce up to 35 mg of 2(E)-hexenal/kg fresh leaves.

Economic and agronomic analysis of conventional and organic concept of cucumber growing

Summary Contemporary agro-technology enables high and stabile yield of slicing cucumber throughout the whole year. This study deals with total costs of production, yield per surface unit and the main parameters of profitability of producing slicing cucumber in the greenhouses and in the open field in conventional and organic farming system. Growing cucumbers in the greenhouses and in accordance with the principles of organic farming are the main conditions for higher prices in the market. The highest total costs (820.00 EUR/are) but also the highest gain (225.00 EUR/are) was realized in producing slicing cucumber both in the greenhouse in the organic farming system. Financial losses were recorded when growing cucumbers in the open field despite lower costs, both in organic and conventional system of growing: 29.00 EUR/are, i.e. -15.00 EUR/are, respectively. The business rate of profitability and the coefficient of cost-effectiveness were higher in growing cucumber in greenhouses in both concepts of production.

Evaluation of Selected Cucurbitaceous Vegetables for Resistance to Zucchini yellow mosaic virus.

Zucchini yellow mosaic virus (ZYMV) causes considerable losses of cucurbitaceous vegetables grown nearly all over the world; indeed, the commonly planted cultivars are highly susceptible to ZYMV. In all, 3 cultivars of American and 8 of European summer squash (Cucurbita pepo), and 6 Japanese and 21 European cucumber lines (Cucumis sativus), including both slicing and pickling species, were selected for the evaluation of their resistance to the most virulent Czech strain, ZYMV-H (GenBank accession number DQ144054). Butternut squash (Cucurbita moschata) 'Menina 15', Chinese slicing cucumber 'Taichung Mou Gua-1' (TMG-1), and watermelon (Citrullus lanatus) accession PI 595203 were included in the experiment, because they were reported to be resistant to ZYMV. The tested plants were mechanically inoculated by ZYMV-H and their resistance was assessed through a comparison of the relative virus protein concentrations and visual symptoms. Butternut squash Menina 15, Chinese slicing cucumber TMG-1, Japanese slicing cucumber breeds 'G22' and 'A192-18', and watermelon PI 595203 were evaluated as immune: the virus concentration in their leaves was zero, as verified by polymerase chain reaction. American summer squash 'Cougar' and Japanese slicing cucumber breeds 'A202-18', 'R10', and 'S93-18' were clearly resistant, because the virus multiplied at a low rate in these plants. The remaining tested cultivars were tolerant or susceptible to ZYMV.

‘Marketmore 97’: A Monoecious Slicing Cucumber Inbred with Multiple Disease and Insect Resistances

‘Marketmore 97’ is the most recent addition to a series of disease-resistant slicing cucumbers developed in the Cornell University Department of Plant Breeding. The fruit have green skin with white spines and an average length and diameter of 18.8 cm and 4.8 cm, respectively. Broad resistance to a number of destructive diseases and insects makes this cultivar well-suited to low-input agricultural systems at the scale of the home gardener or the commercial grower. In addition to the cucumber mosaic virus (CMV), cucumber scab (Cladosporium cucumerinum Ell. & Arth.), downy mildew (Pseudoperonospora cubensis Berk & Curtis), and powdery mildew (Sphaerotheca fuliginea Schl. ex Fr.) resistances of ‘Marketmore 76’, ‘Marketmore 97’ contains resistance to alternaria leaf spot [Alternaria alternata (Fr.) Keis.], Ulocladium leaf spot (Ulocladium cucurbitae Let. & Roum.), target leaf spot (Corynespora cassiicola Berk. & Curt.), watermelon mosaic virus, papaya ringspot virus, and zucchini yellow mosaic virus. Furthermore, the bitterfree character of this cultivar is responsible for nonpreference of the striped cucumber beetle (Acalymma vittatum Fab.) and spotted cucumber beetle (Diabrotica undecimpunctata howardi Barber). Finally, a near isogenic line of ‘Marketmore 97’ is available that is gynoecious. A replicated trial of ‘Marketmore 97’ conducted in New York in 2006 confirmed comparable yield and quality to other Marketmore cultivars.

'NC-Sunshine' and 'NC-Stratford' Slicing Cucumber Hybrids

Four slicing (fresh-market) cucumber inbreds (NC-58, NC-59, NC-62, and NC-63) and two hybrids (‘NC-Stratford’ and ‘NCSunshine’), were developed at North Carolina State University. As with most cucumber cultivars released from N.C. State, ‘NC-Stratford’ and ‘NC-Sunshine’ were named for places around the state. ‘NC-Stratford’ is the F 1 of NC-58 × NC-59, and ‘NC-Sunshine’ is the F 1 of NC-62 × NC-63. The four inbreds have been self-pollinated past the S 12 generation, and were developed from the North Carolina Elite Determinate Slicer (NCEDS) population. The NCEDS population was developed by 1) crossing elite hybrids and inbreds with ‘Spacemaster’ dwarf-determinate inbred in 1983; 2) intercrossing the dwarf-determinate F 2 with dwarf-determinate hybrids and inbreds; and 3) intercrossing the F 1 to form a population for use in recurrent selection. Selection methods were developed that optimized gain for yield and other traits (Wehner, 1989). Selection in the NCEDS population was for fruit shape, and total, marketable and early yield in the spring season, as well as for resistance to foliar fungal diseases in the summer season. The main diseases in the summer were anthracnose [Colletotrichum orbiculare (Berk. and Curt.) Arx] and gummy stem blight [Didymella bryoniae (Auersw.) Rehm]. In addition to yield, earliness, quality and disease resistance, the cucumber families were selected for production of suffi cient seeds to plant the test and intercross plots, rapid seed germination and emergence, rapid vine growth and fl owering, and proper fruit type.

Deterioration of beit alpha and slicing cucumbers ( Cucumis sativus L.) during storage in ethylene or air: Responses to suppression of ethylene perception and parallels to natural senescence

‘Manar’ beit alpha and ‘Thunder’ and ‘Sweet Marketmore’ fresh-market slicing cucumber ( Cucumis sativus L.) fruit were harvested at an immature stage of development (commercial maturity) and subsequently exposed to either air or 1.0 μl l −1 1-methylcyclopropene (1-MCP) prior to storage in air or 10 μl l −1 ethylene at 15 °C. Fruit exposed to 10 μl l −1 ethylene exhibited rapid and acute cellular breakdown reminiscent of other members of the Cucurbitaceae exposed to ethylene. Symptoms were evident following as few as 4 d of ethylene exposure and included fruit softening, mesocarp watersoaking, epidermal sloughing and limited loss of epidermal green color. As one index of cellular deterioration, exposure of ‘Manar’ cucumber to ethylene induced a rapid and significant decline (40%) in total cell wall uronic acid (UA) content compared with losses of about 5–6% in fruit treated with 1-MCP prior to ethylene exposure or in fruit receiving only 1-MCP. Molecular mass downshifts in both water and chelator-soluble pectins (CSP) were markedly accelerated in fruit receiving only ethylene, becoming evident after only 4 d of exposure. In contrast, control fruit receiving neither 1-MCP nor ethylene showed greatly reduced rates of uronic acid loss and pectin depolymerization, with significant declines in molecular mass not being noted until after 16 d of storage at 15 °C. Prior treatment of cucumber fruit with 1-MCP delayed fruit deterioration and pectin depolymerization. Pectin depolymerization was also suppressed in 1-MCP-treated fruit receiving continuous ethylene exposure throughout storage and was substantially lower than rates of depolymerization noted for control fruit. Inhibition of ethylene responsiveness in the fresh-market slicing cucumbers ‘Thunder’ and ‘Sweet Marketmore’ revealed marked differences in cultivar response to the ethylene antagonist. During storage without supplemental ethylene, prior exposure to 1-MCP resulted in significant retention of firmness and surface color in ‘Sweet Marketmore’. In contrast, 1-MCP had minimal effects on these attributes in ‘Thunder’, largely due to higher firmness and color retention of the control fruit in general. Parallels between ethylene-induced deterioration and natural senescence of cucumber fruit are discussed.

Development and Yield of Vegetables Cultivated on Substrate Heated by Geothermal Waters Part I: Bell Pepper, Slicing Cucumber, Tomato

ABSTRACT Polyethylene pipes were buried in the soil at a depth of 0.4 m and spaced at 0.5 and 0.25 m apart in covered tunnels. Geothermal waters with temperatures between 30–45°C, from the final phase of a process that utilized geothermal energy, were pumped through the pipes. The impact of heating by geothermal energy, and the spacing of the heating grid on the growth, development, and productivity of bell pepper, slicing cucumber and tomato was investigated. Acceleration in time to harvest and an increase in yield of vegetables were observed. Heating the tunnels caused yields to be significantly higher than in the unheated tunnels. The 0.25 m spacing of the heating grid sometimes contributed to lowered cucumber and pepper yield, while tomato yield was increased.

Heritability and Genetic Variance Estimates for Leaf and Stem Resistance to Gummy Stem Blight in Two Cucumber Populations

Heritability of resistance to gummy stem blight (Didymella bryoniae (Auersw.) Rehm.) was measured in two diverse cucumber (Cucumis sativus L.) populations [North Carolina elite slicer 1 (NCES1) and North Carolina wide base pickle (NCWBP)]. Heritability was estimated using parent-offspring regression and half-sib family analysis in North Carolina field tests during 1991 and 1992. NCES1 is a slicing cucumber population with a narrow genetic base, and NCWBP is a pickling cucumber population with a wide genetic base. Heritability estimates were low to moderate ranging from 0.12 to 0.49 for the gummy stem blight leaf rating and from -0.03 to 0.12 for stem rating. Estimates of gain from selection were at least two times larger for selection based on half-sib families than for mass selection for all traits in both populations. Approximately three to five cycles of selection would be required to improve the NCES1 population mean for gummy stem blight leaf resistance by one rating scale unit, and three to four cycles of selection would be required to improve the NCWBP population mean for gummy stem blight leaf resistance by one rating scale unit, based on half-sib family selection. One rating scale unit decrease is equivalent to an 11% reduction in susceptibility. Gain would be slower if selecting for stem, or leaf and stem resistance. A moderate amount of additive genetic variation exists in both populations for gummy stem blight leaf resistance, but estimates for additive genetic variation for stem resistance indicate little to no additive genetic variation. Development of populations specifically for greater initial resistance and greater additive variance than found in these populations should aid in selection for resistance.

Fruit Yield and Yield Component Means and Correlations of Four Slicing Cucumber Populations Improved through Six to Ten Cycles of Recurrent Selection

Increased fruit yield in slicing cucumber (Cucumis sativus L.) has been difficult to achieve since yield is quantitatively inherited with low heritability. From 1981 to 1993, four slicing cucumber populations differing in their genetic diversity (wide, medium, elite, and `Beit Alpha') were advanced through six to ten cycles of modified half-sib recurrent selection. The objectives of this research were to determine 1) the fruit yield and yield component means; 2) the correlations between yield components, between yield traits, and between components and yield; and 3) the change in means and correlations with selection for improved yield of four slicing cucumber populations. In 1994 and 1995, four families were randomly selected from three cycles (early, intermediate, and late) from each population and self-pollinated. Thirty plants from each S1 family were evaluated in 3.1-m plots in Spring and Summer 1995 and 1996 at the Horticultural Crops Research Station in Clinton, N.C. Plants were harvested and data were collected on number of branches per plant and nodes per branch, proportion of pistillate nodes, fruit set and shape, and total, early, and marketable yield. When averaged over all populations, seasons, and years, fruit yield and quality increased with selection while yield components remained unchanged with selection. Fruit yield and components differed between populations, seasons, and years. Most correlations between yield components and between yield components and fruit yield were weak, and strong correlations varied between populations, seasons, and yield components. Indirect selection of proportion of pistillate nodes has potential for improving yield for certain population-season combinations. Selection weakened many strong correlations between yield components and between yield and components. Changes in correlations often did not correspond with changes in trait means. Based on this research, selection for yield components would not be advantageous for improving fruit yield in all slicing cucumber populations. Additional yield components, yield component heritability, and better component selection methods need to be determined before component selection can be used to improve fruit yield.

Performance of Three Selection Cycles from Four Slicing Cucumber Populations Hybridized with a Tester

Recurrent selection has been used as a breeding method to improve traits having low heritability such as fruit yield, earliness, and fruit shape. The objective of this study was to measure the progress of recurrent selection in four slicing cucumber populations in terms of hybrid performance when crossed with a common tester. The four populations, North Carolina wide-base slicer (NCWBS), medium-base slicer (NCMBS), elite slicer 1 (NCES1), and Beit Alpha 1 (NCBA1) populations, which differed in their genetic diversity and mean performance, were developed using modified intrapopulation half-sib recurrent selection to improve fruit yield and quality. Eleven S0 families were taken randomly from each of three selection cycles (early, intermediate, and advanced) from each population. Those families were self-pollinated to form S1 families, and the S1 families were crossed to `Poinsett 76', a popular slicing cucumber cultivar. The experiment was a splitplot treatment arrangement in a randomized complete-block design with 22 replications per population, with the four populations as whole plots and the three cycles as subplots. When 10% of fruit were oversized (>60 mm in diameter), plants were sprayed with paraquat to defoliate them for once-over harvest. Plots were evaluated for total, early, and marketable yield and fruit shape. Recurrent selection for improved fruit yield and shape per se resulted in improved hybrid performance of the NCWBS and NCBA1 populations for fruit yield and shape rating when tested in the selected or nonselected environment. The NCWBS population had the largest gain (21%) in hybrid performance averaged over all traits. In addition, early yield was improved an average of 18% from early to late cycles for each population. Even though the fruit yield and shape rating of `Dasher II' was greater than the hybrid performance of each population mean for the same traits, several F1 families within each population exceeded the fruit yield of `Dasher II'.

RECURRENT SELECTION FOR SPECIFIC COMBINING ABILITY FOR YIELD IN FOUR SLICING CUCUMBER POPULATIONS

Plant breeders often measure selection progress for yield by measuring the hybrid performance (combining ability) of a breeding line. This information is used to develop breeding lines with higher combining ability. The objectives of this study were to measure the specific combining ability for yield traits over three selection cycles from four slicing cucumber populations with `Poinsett 76', a popular slicing cucumber cultivar; and to determine the change in specific combining ability for yield traits in four populations improved through recurrent selection. Four slicing cucumber populations, North Carolina wide base slicer (NCWBS), medium base slicer (NCMBS), elite slicer 1 (NCES 1), and Beit Alpha 1 (NCBA1), were developed and improved through modified half-sib selection from 1983 to 1992 to improve yield per se and fruit quality in each population. Eleven families were randomly selected from each of three selection cycles (early, intermediate, advanced) from each population and were hybridized to `Poinsett 76'. Twenty-three seeds from each cross were planted in 1.2-m plots in Spring and Summer 1995. When 10% of fruit were oversized (>50 mm in diameter), plants were sprayed with paraquat to defoliate them and to simulate once-over harvest. The experimental design was a randomized complete block with 22 replications per population arranged in a split plot with the four populations as whole plots and the three cycles as subplots. The combining ability for early and marketable yield of NCWBS and NCBA1 increased as the number of selection cycles increased. Conversely, selection for higher yield per se decreased the combining ability of the NCES 1 population for early and marketable yield. The NCBA1 population exhibited the largest gain (131.2%) from cycle 0 to 8 averaged over all traits. Early yield exhibited the largest gain (60.8%) averaged over all populations.

Ten Cycles of Recurrent Selection for Fruit Yield, Earliness, and Quality in Three Slicing Cucumber Populations

Fruit yield, earliness, and quality have low to moderate heritability, but are traits of major importance in cucumber (Cucumis sativus L.). The objective of this study was to determine the changes made in those traits using recurrent selection in three slicing cucumber populations (NCMBS, NCES1, and NCBA1). During population improvement, one or two replications of 200 to 335 half-sib families were evaluated in the spring season for five traits: total, early, and marketable fruit per plot, fruit shape rating, and a simple weighted index (SWI = 0.2(total yield)/2 + 0.3(early yield) + 0.2(% marketable)/10 + 0.3(fruit shape). Families from each population were intercrossed in an isolation block during the summer season using remnant seeds of the best 10% selected using the index. Response was evaluated using a split-plot treatment arrangement in a randomized complete block design with 32 replications in each of two seasons (spring and summer). Whole plots were the three populations, and subplots were the 11 cycles (cycles 0 to 9 plus checks). We measured improvement in performance of the populations in a selected (spring) and unselected environment (summer). Significant gains were made for all traits in all populations over the 9 to 10 cycles of recurrent selection. Greatest progress was made for the NCMBS population, with an average of 37% gain from cycle 0 to 9 over all five traits. The trait where most progress was made was early yield, with an average of 63% gain from cycle 0 to 9 over the three populations.

The breeding of scab-resistant frame cucumbers in the Netherlands

Scab caused by the fungus Cladosporium cucumerinum, may cause serious damage to frame cucumbers. Bulbosan (trichlorotrinitrobenzene) is an effective chemical means of control. Between 1945 and 1954 this German fungicide could not be supplied, and, as a result, the need for resistant varieties became very great. Before 1920 scab-resistance in pickling cucumbers was already known to Dutch growers. Selection started around 1920 on the initiative of W. G. v. d. Kroft and resulted in scab-resistant pickling cucumbers of which Baarlose Nietplekker VI is still widely grown. In 1948 G. W. v. d. Helm (Exp. Garden at Sloten) started breeding a scab-resistant yellow slicing cucumber destined for gardeners in the neigh-bourhood of Amsterdam. The resistant variety Highmoor was used as one parent. In 1954 the yellow variety Vios and the white variety Mabro were introduced. In 1952 G. W. v. d. Helm at the Exp. Garden Sloten, and J. M. Andeweg at the Institute of Horticultural Plant Breeding, Wageningen, simultaneously started breeding green scab-resistant frame cucumbers, using Highmoor as the resistant parent. In 1955 the experimental garden at Sloten introduced the scab-resistant green slicing cucumbers Amato and Proso, while in 1956 the Institute of Horticultural Plant Breeding introduced the scab-resistant green slicing cucumber Esvier. In 1953 seed of 2 first-backcross populations was supplied by the Institute to seed growers. At present intensive breeding for scab-resistance is also being carried out by a number of Dutch seed growers. Scab-resistance depends on one dominant gene; and young plants can readily be tested for resistance. Consequently a backcross scheme can easily be carried out. Rapid breeding is possible because at least 2 cultures can be carried out yearly. If necessary, cuttings of promising plants can be taken. Before and after artificial pollination the flowers can be tied up with raffia. It is simpler, however, to pinch the flowers with a special stainless clip as originally used for grafting cucumbers. The uniform fruit colour of the Dutch green frame slicing cucumbers is a recessive character; the fruit length of the Dutch varieties is dominant.