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Growing guidelines for Short Cucumbers Reproduced by kind permission of De Ruiter Seeds Inc. The information in this article has been carefully compiled. HOWEVER, De Ruiter Seeds and Paramount Seeds cannot be held liable or accept liability for the accuracy of the given information nor for the result or effect of the implementation of such information. Soil Cucumbers grow best in humus-rich soils, pH-KCI 5-6, with good structure and drainage. A light, deep sandy-loam soil which has been regularly enriched with organic material is ideal, because a light well-aerated soil is essential for the root development. Soils with poor drainage need to be very carefully worked in order to prevent saturation problems. Cucumbers are highly sensitive to excessive salt levels and the salt concentration in the soil (expressed as E.C. = Electric Conductivity) should not exceed 2 mS. An excessive salt concentration hinders the nutritional uptake by the roots and this results in a reduction in vegetative growth. Extra fertilizer gifts increase the osmotic pressure and in this case will only make matters worse. Water The quality of the water depends on the pH and the salt concentration. A high pH can be neutralized by the addition of acidic fertilizers. Where the salt level exceeds 2 mS and there is no possibility for the desalination of the water, cucumber culture is inadvisable. When sweet water is available then a high salt concentration in the soil need not form a problem. Using drip irrigation, the excessive salt around the roots can be washed out. At the same time to achieve an optimal result the water and the salts dissolved up in it must be given in the correct dosage and frequency. Soil preparation A well-prepared soil is essential for both sowing and planting. Drip irrigation applies the inorganic fertilizer locally around the plant, furrow irrigation applies it over the whole surface. With drip irrigation the plant's root system is restricted to that area of the soil moistened by the system. The organic matter present in the soil enables the root system to absorb nutritional elements, prevents micro-elements being bound to the soil and functions as a buffer for the salt concentration. Farm manure can be used as organic fertilizer. Use up to 50 tons per ha per year. The manure must be well-rotted to avoid any scorching of the plants through the release of ammonia. Work humus and phosphorus (in the form of super phosphate) into the soil a few weeks before planting. On very calcareous soils (pH over 7.5) the phosphorus is fixed and up to 2,000 kg super phosphate 18% can be given. The beds should be slightly raised and the irrigation lines laid out. These are then covered with plastic foil to minimize evaporation and prevent the rise of salts to the surface. Sowing and planting methods for different seasons. Planting and sowing dates Cucumbers can be sown or planted throughout the year, however the date will depend upon market price for the product and the winter and summer temperatures. On thoroughly disinfected soils it is preferable to sow for autumn production directly into the soil rather than plant out pot-plants. Cucumbers grown in pots tend to grow weak and straggly in warm weather. Early spring sowing is best done in pots or in rock wool plugs. On insufficiently disinfected soils, Pythium and Rhizoctonia may well affect young plants. The seeds should be treated beforehand with TMTD, this is common practice for De Ruiter Seeds. Plant distance The plant distance depends on glass, tunnel-house width, local custom and the variety grown. Vigorous plants take up more space than slow growing varieties. A density of 2-3 plants per square meter for the short cucumber types is advised. The plants can be planted in either single or double rows, but the density mentioned should be maintained to give plants sufficient light and air. Spring production The aim is to harvest as early as possible. Early and-healthy plant material can be achieved by sowing and raising the plants in pots. The pots should be placed in a warm sheltered situation. For spring production choose an early variety which is not too vigorous. Summer production In Mediterranean and Middle-East countries no summer production is undertaken unless the field or greenhouse is at a higher altitude. In northern countries however, summer is an important growing season. Here we find rock wool cultures with plants raised in rock wool blocks. Autumn and winter production Early autumn production is an important production period. In northern countries when the culture is extended into the winter there is a risk of necrosis due to poor light and plants at the end of their production period. In Mediterranean and Middle-East countries late autumn and winter production show no ill effects as there is sufficient light available. A limiting factor can be temperatures which are too low. Plant a fairly vigorous variety in disinfected soil. The advantage of this production is the high price fetched by cucumbers in the winter months. Plants must therefore be in full production at this time. They must also be strong enough to restart growth after the cold period. The aim is to raise well-balanced plants with a high productive capacity throughout the cold period, which afterwards either continue production or pick it up again after some time. Trimming The aim of trimming is to influence or regulate the balance between vegetative and generative growth. It is also done to give the plants more air and in this way stimulate leaf respiration and counteract disease. The method for trimming short cucumbers differs from the long cucumber method. Trim all side shoots back to 2 leaves below the top supporting wire. For deformation of the fruits it is also advisible to remove all fruits, fruit buds and side shoots below the 0.5 m level. Some hybrids have been bred which do not produce long side shoots so saving trimming costs Removing all fruits below the 0.5 m level means losing the earliness in the crop. However, this will be compensated because low-growing fruits could have exhausted the young plants. Once the plant reaches the horizontal wire, all side shoots can be allowed to develop. The plant has by then formed sufficient foliage to sustain a large number of fruits. Nutrition Uninterrupted and well-balanced growth is important in a cucumber plant production. An even and regular supply of water and nutrients is therefore necessary. With cucumbers grown in soil the climatic conditions in the greenhouse can be controlled but the soil remains an uncontrollable variable. Nevertheless one should still aim at uninterrupted and well-balanced growth. Using drip irrigation, water and dissolved nutrients can be administered regularly. At the start of the culture apply just sufficient water for the plant to develop. After the first harvest of some of the fruits the water gift can be almost doubled. However, the correct amount of water and nutrients depends very much on climatic conditions and the stage of plant development. Scab (Cladosporium cucumerinum) Foliar spots at first vitreous, then greyish. Their centre can be covered by a greyish powder on the surface. Scab can extend to well-limited spots on the stem. Leafspot (Corynespora cassiicola) Big angular spots on the edge of the leaf; yellow then brown. On fruit the rot is localized at the apical extremity. Powdery Mildew (Sphaerotheca fuliginea) Superficial round spots of variable size, mainly on the upper leaf surface, covered with white powder. Downy Mildew (Pseudoperonospora cubensis) Vein-bounded spots on leaves. First translucent, later yellow. Damping off (Pythium, Rhizoctonia, Fusarium or Phytophtora). Collar necrosis on the seedling (Pythium) or collar rot on the young plant. Black root rot (Phomopsis sclerotioides) A thick and longitudinally cracked root collar. Small longitudinally necrotic spots on the rootlets are bordered black. Growth stoppage and weak appearance of the plant. The ends of rootlets turn from brown to black. Verticillium wilt Wilt appears during the warm period of the day and disappears during the night. Fusarium (Fusarium oxysporum) Distinct progressive yellowing of leaves. Yellowing begins on half a leaf, brown vessels in the stem and gum exudes from the stem. Grey mould (Botrytis cinerea) Diffused zones starting at the stem nodes, damp rot covered by greyish dust. Can start up from wounds. On fruits rot is localized at the apical extremity. Black stem rot (Didymella bryoniae or Mycosphaerella melonis) Usually first symptoms are seen on wounds like Botrytis. Grey to pale brown spots covered up by small black dots. sometimes grouped in concentric circles. Seen on leaves and stem. On fruit rot is localized at the apical extremity. Cucumber Virus 1 Permanent wilt accompanied, or followed by, a mosaic on young leaves. Cucumber Virus 2 Shrivelling of the ends of lateral shoots.
EXPLANATION OF TERMS USED Resistant The ability of the plant to interfere with the development of a certain disease or certain pathotypes of that disease. Resistant is a relative conception. Tolerant The ability of the plant to endure a certain disease or harmful environmental factor with little adverse effect on its growth and production. Susceptible The disability of the plant to hinder or control the growth and/or development of a certain disease or environmental factor. |
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