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    Saturday, September 27, 2014

    How to cultivate Cucumber!. (MATANGO NA FAIDA ZAKE)


    Description
    Uses
    Propagation
    Useful resources
    Diseases
    Cucumber

    Description

    Cucumber, Cucumis sativus, is a warm season, vining, annual plant in the family Cucurbitaceae grown for its edible cucumber fruit. The cucumber plant is a sprawling vine with large leaves and curling tendrils. The plant may have 4 or 5 main stems from which the tendrils branch. The leaves of the plant are arranged alternately on the vines, have 3–7 pointed lobes and are hairy. The cucumber plant produces yellow flowers that are 4 cm (1.6 in) in diameter. The cucumber fruit varies in shape but is generally a curved cylinder rounded at both ends that can reach up to 60 cm (24 in) in length 10 cm (3.9 in) in diameter. Cucumber plants are annual plants, surviving only one growing season and the vines can reach up to 5 m (16.4 ft) in length. Cucumber may also be referred to as gherkin and originates from the foothills of the Himalayas, likely in India.

    Uses

    Although technically a fruit, cucumbers are used as a fresh vegetable, consumed fresh in salads. Some varieties are grown specifically for pickling. Yellow varieties are generally cooked before consumption. 

    Propagation


    Requirements
    Cucumbers require warm, dry conditions to develop optimally, preferring both warm days and warm nights and growing best at a temperature of 30°C (86°F). Cucumbers will yield best if grown in a fertile, well-draining soil, rich in organic matter and with a pH between 6.5 and 7.5. Cucumbers are very sensitive to cold and should be planted in full sun and provided with ample soil moisture due to their shallow root system. 

    Cucumber varieties
    One of the biggest considerations when choosing a cucumber variety is whether or not it requires pollinating. Many newer cucumber varieties are gynoecious which means that they produce only, or mostly, female flowers. Some gynoecious varieties require pollinating with male flowers, in which case a proportion of the seeds in the packet will be pollinator plants which produce the male flowers. Some gynoecious varieties are parthenocarpic which means that they do not need the male plants to produce fruit. These types are recommended for growing in glasshouses as they do not require the presence of insect pollinators. 

    Sowing seeds
    Direct seeding is the preferred method for sowing cucumbers as they do not transplant well. Seeds should be sown after the last frosts and when the soil has warmed to at least 15.6°C (60°F). Sow seeds 1.3–2.5 cm (0.5–1.0 in) deep, thinning to a spacing of at least 30 cm (12 in) between plants after germination. Cucumbers can also be seeded on hills or mounds of soil to encourage warm soil and better drainage. In this instance, seeds should be sown on hills in groups of 4–6 seeds, allowing 1.2 m (4 ft) between each group in all directions. After emergence, thin the seedlings to 1 or 2 plants per hill. Cucumber seeds should germinate in 4–13 days depending on the soil temperature. 

    General care
    Cucumber vines are sprawling and require plenty space to grow. Vines can be trained to grow on a trellis or fence. Providing burpless varieties with vertical support allows the fruits to hang loose and grow straight. Cucumbers also require a continuous supply of water and where drip irrigation is not being used, plants should be watered deeply once per week, providing at least an inch of water. Shallow watering or watering less frequently will reduce fruit yields. Mulches can be used to conserve soil moisture and black plastic mulch has the advantage of warming the soil. 

    Harvesting
    Cucumbers should be harvested from the plant when they are still immature and green in color. Mature fruits are yellow and the flesh is often tough with woody seeds. The size of cucumbers at harvest depends on the variety of the cucumber being grown and what it is to be used for. Cucumbers for pickling are generally picked when they are less than 5 cm (2 in) long whereas burpless cucumbers for slicing should be allowed to reach approximately 4 cm (~1.5 in) in diameter. It is important to remove any fruits nearing maturity to ensure the plant remains productive. Their rapid growth means that cucumbers may need harvested every couple of days.

    Common Pests and Diseases

    Angular leaf spotPseudomonas syringae
    Symptoms
    Small water-soaked lesions on leaves which expand between leaf veins; lesions turn tan and may have yellow/green edges; a white crust may be present on or beside lesions
    Cause
    Bacteria
    Comments
    Spread through infected seed, splashing rain, insects and movement of people between plants; bacterium overwinters in crop debris and can survive for 2.5 years
    Management
    Use disease-free seed; do not grow plants in field where cucurbits have been grown in the previous 2 years; protective copper spray may help reduce incidence of disease in warm, humid climates; plant resistant varieties

    Bacterial wilt Erwinia tracheiphila
    Symptoms
    Slimy dull green patches on leaves and stems; leaves appear dark green; dark discoloration on leaves and stems; rapid plant death
    Cause
    Bacterium
    Comments
    Can result in crop losses of of 75%; spread by striped or spotted cucumber beetles; disease can be confirmed by cutting the stem and slowly pulling the two ends apart - infected plants will ooze strings of bacterial exudate
    Management
    Control cucumber beetle populations on plants; hand pick adult beetles and destroy; soil and foliar application of appropriate insecticides may help to control populations

    Anthracnose Colletotrichum orbiculare
    Symptoms
    Brown roughly circular lesions with yellow edges on leaves on leaves, petioles, stems and/or fruit; lesions on resistant varieties appear tan with green edges; lesions dry out and drop out of leaves
    Cause
    Fungus
    Comments
    Disease favors warm temperatures
    Management
    Plant resistant varieties; use only certified seed; apply appropriate protective fungicides; rotate crops every year

    Belly rot (Fruit rot, Damping-off) Rhizoctonia solani
    Symptoms
    Yellow/brown discoloration on fruit; water soaked spots on side of fruit in contact with soil; brown mold growing on rotting areas; collapse of seedlings
    Cause
    Fungus
    Comments
    Disease favors warm, humid condtions
    Management
    Till soil deeply prior to planting; use plastic mulch to create a barrier between fruit and soil; plant in sites with good drainage to avoid wet soils; apply appropriate protective fungicides when plants begin to vine

    Downy mildew Pseudoperonospora cubensis
    Symptoms
    Fluffy purplish mildew on underside of leaves; yellow spots on the upper side of leaves
    Cause
    Fungus
    Comments
    Disease favors cool, humid conditions
    Management
    Do not overcrowd plants; avoid overhead irrigation, water plants from base; apply appropriate fungicide

    Fusarium wilt (Cucumber wilt, Foot-rot) Fusarium oxysporum
    Symptoms
    Rotting of seedling stems at soil line; brown lesions on one side of stem; discoloration of tissue inside vine
    Cause
    Fungus
    Comments
    Disease favors warm, moist soil
    Management
    Plant fungicide treated seed; rotate crops on 4 year rotation

    Gummy stem blightMycosphaerella melonis
    Symptoms
    Gray/green lesions between veins of leaves; tan or gray lesions on stems
    Cause
    Fungus
    Comments
    Disease may be seed-borne
    Management
    Use disease free seed; treat seeds prior to planting; rotate crops every 2 years

    Target leaf spot Corynespora cassiicola
    Corynespora. melonis
    Symptoms
    Angular yellow spots on mature leaves which enlarge and form circular lesions with light brown center and dark brown margins; lesions turn gray and drop out of leaf causing a shot hole appearance
    Cause
    Fungus
    Comments
    Fungus can survive on plant debris for periods in excess of 2 years; disease emergence favored by periods of high humidity and temperature
    Management
    Plant resistant varieties; apply appropriate protective fungicide; sanitize equipment regularly

    Mosaic Cucumber mosaic virus (CMV)
    Symptoms
    Mottling on leaves; downward growth of petioles; wrinkled, curled, and distorted leaves
    Cause
    Virus
    Comments
    Transmitted by aphids; virus has an extensive host range; can be mechanically transmitted via tools etc.
    Management
    Plant resistant varieties; use reflective mulches to deter aphids; apply appropriate insecticides to kill aphids

    Cucumber beetles (Western striped cucumber beetle, Western spotted cucumber beetle, Banded cucumber beetle) Acalymma vittata
    Diabrotica undecimpunctata
    Diabrotica balteata
    Symptoms
    Stunted seedling; damaged leaves, stems and/or petioles; reduced plant stand; plants may exhibit symptoms of bacterial wilt; scars on fruit caused by beetle feeding damage; adult beetles are brightly colored with either a green-yellow background and black spots or alternating black and yellow stripes
    Cause
    Insect
    Comments
    Beetles overwinter in soil and leaf litter and emerge from soil when temperatures begin to reach and exceed 12.7°C (55°F)
    Management
    Monitor new planting regularly for signs of beetle; floating row covers can be used to protect the plants from damage but will need to be removed at bloom to allow bees to pollinate plants; applications of kaolin clay can be effective for management of small beetle populations; application of appropriate insecticides may be necessary

    Cabbage looper Trichoplusia ni
    Symptoms
    Large or small holes in leaves; damage often extensive; caterpillars are pale green with a white lines running down either side of their body; caterpillars are easily distinguished by the way they arch their body when moving; eggs are laid singly, usually on the lower leaf surface close to the leaf margin, and are white or pale green in color
    Cause
    Insect
    Comments
    Insects overwinter as pupae in crop debris in soil; adult insect id a dark colored moth; caterpillars have a wide host range
    Management
    Looper populations are usually held in check by natural enemies; if they do become problematic larvae can be hand-picked from the plants; an organically acceptable control method is the application of Bacillus thuringiensis which effectively kills younger larvae; chemical sprays may damage populations of natural enemies and should and should be selected carefully

    Flea beetles Epitrix spp.
    Symptoms
    Small holes or pits in leaves that give the foliage a characteristic “shothole” appearance; young plants and seedlings are particularly susceptible; plant growth may be reduced; if damage is severe the plant may be killed; the pest responsible for the damage is a small (1.5–3.0 mm) dark colored beetle which jumps when disturbed; the beetles are often shiny in appearance
    Cause
    Insects
    Comments
    Younger plants are more susceptible to flea beetle damage than older ones; older plants can tolerate infestation; flea beetles may overwinter on nearby weed species, in plant debris or in the soil; insects may go through a second or third generation in one year
    Management
    In areas where flea beetles are a problem, floating row covers may have to be used prior to the emergence of the beetles to provide a physical barrier to protect young plants; plant seeds early to allow establishment before the beetles become a problem - mature plants are less susceptible to damage; trap crops may provide a measure of control - cruciferous plants are best; application of a thick layer of mulch may help prevent beetles reaching surface; application on diamotecoeus earth or oils such as neem oil are effective control methods for organic growers; application of insecticides containing carbaryl, spinosad, bifenthrin and permethrin can provide adequate control of beetles for up to a week but will need reapplied

    Aphids (Peach aphid, Melon aphid) Myzus persicae
    Aphis gossypii
    Symptoms
    Small soft bodied insects on underside of leaves and/or stems of plant; usually green or yellow in color, but may be pink, brown, red or black depending on species and host plant; if aphid infestation is heavy it may cause leaves to yellow and/or distorted, necrotic spots on leaves and/or stunted shoots; aphids secrete a sticky, sugary substance called honeydew which encourages the growth of sooty mold on the plants
    Cause
    Insects
    Comments
    Distinguishing features include the presence of cornicles (tubular structures) which project backwards from the body of the aphid; will generally not move very quickly when disturbed
    Management
    If aphid population is limited to just a few leaves or shoots then the infestation can be pruned out to provide control; check transplants for aphids before planting; use tolerant varieties if available; reflective mulches such as silver colored plastic can deter aphids from feeding on plants; sturdy plants can be sprayed with a strong jet of water to knock aphids from leaves; insecticides are generally only required to treat aphids if the infestation is very high - plants generally tolerate low and medium level infestation; insecticidal soaps or oils such as neem or canola oil are usually the best method of control; always check the labels of the products for specific usage guidelines prior to use

    Cutworms Agrotis spp.
    Peridroma saucia
    Nephelodes minians
    and others
    Symptoms
    Stems of young transplants or seedlings may be severed at soil line; if infection occurs later, irregular holes are eaten into the surface of fruits; larvae causing the damage are usually active at night and hide during the day in the soil at the base of the plants or in plant debris of toppled plant; larvae are 2.5–5.0 cm (1–2 in) in length; larvae may exhibit a variety of patterns and coloration but will usually curl up into a C-shape when disturbed
    Cause
    Insects
    Comments
    Cutworms have a wide host range and attack vegetables including asparagus, bean, cabbage and other crucifers, carrot, celery, corn, lettuce, pea, pepper, potato and tomato
    Management
    Remove all plant residue from soil after harvest or at least two weeks before planting, this is especially important if the previous crop was another host such as alfalfa, beans or a leguminous cover crop; plastic or foil collars fitted around plant stems to cover the bottom 3 inches above the soil line and extending a couple of inches into the soil can prevent larvae severing plants; hand-pick larvae after dark; spread diatomaceous earth around the base of the plants (this creates a sharp barrier that will cut the insects if they try and crawl over it); apply appropriate insecticides to infested areas of garden or field if not growing organically

    Stinkbugs (Various) Various
    Symptoms
    Dark colored pinpricks on fruit surrounded by a lighter area that turns yellow or remains light green; stink bugs often carry pathogens in their mouthparts which can cause secondary infections and decay of fruit; adult insect is shield-shaped and brown or green in color; may have pink, red or yellow markings; eggs are drum shaped and laid in clusters on the leaves; larvae resemble the adults but are smaller
    Cause
    Insect
    Comments
    Adult insects overwinter under leaves, on legumes, blackberries or on certain weeds such as mustard or Russian thistle
    Management
    Remove weeds around crop which may act as overwintering sites for stink bugs and practice good weed management throughout the year; organically accepted control methods include the use of insecticidal soaps, kaolin clay and preservation of natural enemies; chemical treatments are not recommended for tomatoes that are to be processed for paste or canning unless secondary infections with other pathogens are a concern

    Thrips (Western flower thrips, Onion thrips, etc.) Frankliniella occidentalis
    Thrips tabaci
    Symptoms
    If population is high leaves may be distorted; leaves are covered in coarse stippling and may appear silvery; leaves speckled with black feces; insect is small (1.5 mm) and slender and best viewed using a hand lens; adult thrips are pale yellow to light brown and the nymphs are smaller and lighter in color
    Cause
    Insect
    Comments
    Transmit viruses such as Tomato spotted wilt virus; once acquired, the insect retains the ability to transmit the virus for the remainder of its life
    Management
    Avoid planting next to onions, garlic or cereals where very large numbers of thrips can build up; use reflective mulches early in growing season to deter thrips; apply appropriate insecticide if thrips become problematic
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