مقالات

( Cabbage (red , white, Savoy

(Cabbage (red, white, Savoy

Description

The cabbage plant, Brassica oleracea, is an herbaceous annual or biennial vegetable in the family Brassicaceae grown for its edible head. There are many different varieties of cabbage which include the white and red cabbage (Brassica oleracea var. capitata) and the savoy cabbage (Brassica oleracea var. sabauda. The head of the cabbage is round and forms on a short thick stem. The leaves are thick and alternating with wavy or lobed edges and the roots are are fibrous and shallow. The plant produces large yellow flowers. The densely leaved heads can range in size from 0.5 to 3.6 kg (1-8 lb) depending on variety. The plant is usually grown as an annual. Brassica oleracea may be referred to as cabbage, Shetland cabbage, Savoy cabbage, white cabbage or red cabbage and is believed to have originated from a wild cabbage ancestor in ancient Asia minor.

Cabbage leaves

Close-up of cabbage foliage

Field of cabbages

Fields of cabbage

Red cabbage

Cabbage leaves

Uses

Cabbage is primarily grown for consumption as a vegetable, eaten after boiling or steaming. Some cultivars are grown as fodder for animals. Red cabbage is commonly pickled.

Propagation

Basic requirements Cabbage is cool season crop that grows best in cool, moist conditions. The plant will grow best at temperatures between 4 and 21°C (40–50°F) allowing it to be grown in both Spring and Fall. Cabbage will grow optimally in a rich, moist, well draining soil With a pH of 6.5. The plant requires at least six hours of direct sunlight every day. Sowing seeds Cabbage can be direct seeded or started indoors to produce transplants. The optimum soil temperature for germination is between 12 and 24°C (55–75°F). Cabbage seeds can be planted outdoors 6–8 weeks before the last spring frost date in a cold frame and transplanted to their final location approximately 4 weeks before the last frost. If planting for a fall harvest, cabbage can be direct seeded 6–8 weeks before the first frost date. Prepare the soil for planting through the addition of nitrogen in the form of bone meal or composted manure. Plant cabbage seeds 6 mm (0.25 in) deep allowing 10–15 cm (4–6 in) between plants in the row and a 0.6 to 1.2 m (2–4 ft) between rows. Thin seedlings to a final within row spacing of 45–60 cm (18–24 in). Keep soil moist during germination to prevent a crust from forming on the soil surface as this will cause uneven germination. Transplanting Seedlings started indoors or in a cold frame are ready to be transplanted when they have 3–4 leaves and the daytime temperature has reached 10°C (50°F). Seedling should be planted at the final spacing for seeds (45–60 cm/18–24 in between plants and 0.6 to 1.2 m/2–4 ft between rows). Plant each seedling slightly deeper than it was previously. The plantings can be staggered in 2 week intervals to prolong the harvest. General care and maintenance Cabbage should be kept evenly watered to ensure the development of tight heads. Uneven watering can cause heads to crack. Application of mulch around plants helps to conserve soil moisture. Cabbage plants have shallow roots and in order to avoid damaging them, it is preferable to hand pull any weeds growing around the plants. Cabbages are heavy feeders and require the addition of fertilizer to meet their growth requirements and develop optimally. Fertilize the plants when they are beginning to form new leaves and starting to develop heads. Harvesting Cabbages are ready to harvest when the head is fully formed and feels firm and well-packed when squeezed. Cut the head away from the stalk with a sharp knife. Leaving the stalks in the ground will result in the formation of several smaller heads which can also be harvested and eaten.

Cabbage seedlings

Cabbages can be started in a cold frame and transplanted

References

CABI Crop Protection Compendium. (2008). Brassica oleracea datasheet. Available at: http://www.cabi.org/cpc/datasheet/10102. [Accessed 07 November 14]. Paid subscription required. Delahaut, K. A. & Newenhouse, A. C. (1997). Growing Broccoli, Cauliflower, Cabbage and other Cole crops in Wisconsin. A Guide for Fresh-Market Growers. University of Wisconsin Cooperative Extension. Available at: http://learningstore.uwex.edu/assets/pdfs/A3684.PDF. [Accessed 07 November 14]. Free to access Rimmer, S. R., Shattuck, V. I. Buchwaldt, L. (Eds) (2007). Compendium of Brassica Diseases. American Phytopathological Society Press. Available at: http://www.apsnet.org/apsstore/shopapspress/Pages/43443.aspx. Available for purchase from APS Press.

Common Pests and Diseases

Diseases

Category : Fungal

Alternaria leaf spot (Black spot, Gray spot) Alternaria brassicae

Symptoms of Alternaria leaf spot on cabbage

Close-up of Alternaria lesion on cabbage leaf

Leaf spot on cabbage caused by Alternaria brassicicola

Black spot infected cabbage leaf

Concentric balck spots on leaf

(Cabbage infected withblack spot (Alternaria brassicicola

Chinese cabbage leaf showing many lesions caused by Alternaria brassicicola

Initial symptoms on Chinese cabbage leaf

Symptoms

Small dark spots on leaves which turn brown to gray; lesions may be round or angular and may possess a purple-black margin; lesions may form concentric rings, become brittle and crack in center; dark brown elongated lesions may develop on stems and petioles.

Cause

Fungus

Comments

May become a problem on cabbage during cool, wet periods.

Management

Plant only pathogen-free seed; rotate crops; applications of appropriate fungicides control disease when present.

Anthracnose Colletotrichum higginsianum

Anthracnose symptoms on cabbage leaf

anthracnose (Colletotrichum higginsianum) symptoms on turnip leaf

Symptoms

Small circular or irregularly shaped dry spots which are gray to straw in color on leaves; a high number of spots may cause the leaf to die; lesions may coalesce to form large necrotic patches causing leaves to turn yellow and wilt; lesions may split or crack in dry centers.

Cause

Fungus

Comments

Fungus overwinters on leaf debris and on related weeds; disease emergence is favored by moist, warm conditions.

Management

Control of disease depends on sanitary practices; treat seeds with hot water prior to planting; rotate crops; plant in an area with good soil drainage; remove all cruciferous weeds which may act as a reservoir for the fungus.

Black rot Xanthomonas campestris.

Early symptoms of black rot showing V-shaped lesion on cabbage leaf

Black rot symptoms include large lesion on the margin of the leaves that causes sever leaf damage and yield losses on cabbage.

The symptoms starts as V-shaped yellow lesions to the margin of the leaves. If the disease infection starts early i the season the entire plant can be severely affected. Blackened veins is another major symptom of black rot on cabbage.

Cabbage leaf with scorched appearance cuased by black rot infection

A field with severe infection of black rot

Initial infection begins as yellow “V” shaped spot on edge of leaf. Black veins eventually appear as infection spreads.

Savoy cabbage infected with black rot

Typical V-shaped marginal chlorosis and necrosis caused by black rot.

Symptoms on stem

Symptoms on stem

Bacterial streaming from cut tissue

Classic bright yellow lesions at the leaf margins

Symptoms

Irregularly shaped dull yellow areas along leaf margins which expand to leaf midrib and create a characterstic “V-shaped” lesion; lesions may coalesce along the leaf margin to give plant a scorched appearance.

Cause

Bacterium

Comments

Pathogen is spread via infected seed or by splashing water and insect movement; disease emergence favored by warm and humid conditions.

Management

Primary method of controlling black rot is through the use of good sanitation practices; rotate crops to non-cruciferous crops every 2 years; plant resistant varieties; control cruciferous weed species which may act as a reservoir for bacteria; plant pathogen-free seed.

Clubroot Plasmodiophora brassicae

Cabbages in field showing symptoms of poor growth due to club root

Distorted roots of cabbage plant caused by infection with club root fungus

Symptoms
Slow growing, stunted plants; yellowish leaves which wilt during day and rejuvenate in part at night; swollen, distorted roots; extensive gall formation
Cause
Fungus
Comments
Can be difficult to distinguish from nematode damage; fungus can survive in soil for periods in excess of 10 years; can be spread by movement of contaminated soil and irrigation water to uninfected areas
Management

Once the pathogen is present in the soil it can survive for many years, elimination of the pathogen is economically unfeasible; rotating crops generally does not provide effective control; plant only certified seed and avoid field grown transplants unless produced in a fumigated bed; applying lime to the soil can reduce fungus sporulation

Damping-off (Wirestem, Head rot) Rhizoctonia solani

Rotting lesion on cabbage leaf caused by infection with Rhizoctonia

Symptoms
Death of seedlings after germination; brown or black rot girdling stem; seedling may remain upright but stem is constricted and twisted (wirestem); in older cabbage plants sharply defined brown lesions appear on the underside of leaves; the lesions expand causing leaves to wilt and drop from plant
Cause
Fungus
Comments
Disease emergence in seedlings favored by cool temperatures
Management

Plant pathogen-free seed or transplants that have been produced in sterilized soil; apply fungicide to seed to kill off any fungi; shallow plant seeds or delay planting until soil warms

Powdery mildew Erysiphe cruciferarum

Powdery mildew Erysiphe cruciferarum

Powdery mildew

 

Symptoms

Small white patches on upper and lower leaf surfaces which may also show purple blotching; patches coalesce to form a dense powdery layer which coats the leaves; leaves become chlorotic and drop from plant .Irregularly shaped patches of white, powdery mould on the upper surface of leaves and stems, particularly older leaves. Occasionally also on the lower leaf surface.

Cause

Fungus

Comments

Disease emergence favored by dry season, moderate temperatures, low humidity and low levels of rainfall

Management

Plant resistant varieties; rotate crops; remove all crop debris after harvest; remove weeds; avoid excessive application of nitrogen fertilizer which encourages powdery mildew growth; powdery mildew can be controled by application of sulfur sprays, dusts or vapors

Sclerotinia stem rot (White mold) Sclerotinia sclerotiorum

Symptoms

Irregular, necrotic gray lesions on leaves; white-gray leions on stems; reduced pod set; shattering seed pods

Cause

Fungus

Comments

Disease emergence favors moderate to cool temperatures and high humidity

Management

Rotate crop to non-hosts (e.g. cereals) for at least 3 years; control weeds; avoid dense growth by planting in adequately spaced rows; apply appropriate foliar fungicides

Watery soft rot (White rot, Cabbage drop) Sclerotinia sclerotiorum

Cabbage infected with Sclerotinia

Cabbage head infected with Sclerotinia

Sclerotinia fungus on cauliflower

Symptoms

Soft rotting area at base of stem which spreads upwards successively killing leaves by causing them to drop and infect the leaf below; when fungus reaches the head it causes a soft, slimy, watery rot

Cause

Fungus

Comments

Disease emergence is favored by frequent rainfall that keep soil close to saturation

Management

The number of sclerotia in the soil can be reduced by plowing crop debris deep into soil and rotating crops every 3 years with non-host crops; severe infestations may require control through application of appropriate fungicide

White rust Albugo candida

Symptoms

White pustules on cotyledons, leaves, stems and/or flowers which coalesce to form large areas of infection; leaves may roll and thicken

Cause

Fungus

Comments

Fungus can survive for long periods of time in dry conditions; disease spread by wind

Management

Rotate crops; plant only disease-free seed; apply appropriate fungicide if disease becomes a problem

Category : Bacterial

Bacterial soft rot Erwinia caratovora

Bacterial soft rot on cabbage

Bacterial soft rot on cabbage

Cabbage head with decay from soft-rotting, bacterial infection.

Bacteria streaming from soft-rotted tissue under dark-field observation.

Symptoms

Water-soaked lesions on cabbage head which expand to form a large rotted mass of cream colored tissue which is liquid underneath; surface of lesions usually crack and exude slimy liquid which turns tan, dark brown or black on exposure to air.

Cause

Bacterium

Comments

Bacteria are easily spread on tools and by irrigation water; disease emergence favored by warm, moist conditions.

Management

Chemical treatments are not available for bacterial soft rot, control relies on cultural practices; rotate crops; plant cabbage in well-draining soils or raised beds; only harvest heads when they are dry; avoid damaging heads during harvest.

Blackleg Leptosphaeria maculans

Leaf disease symptoms caused by Leptosphaeria maculans on Brassica napus. The leaf on the left shows necrosis caused by the fungus include production of black pycnidia within the white lesions, whereas the younger leaf on the right is relatively disease free.

Symptoms

Damping-off of seedlings; round or irregularly shaped gray necrotic lesions on leaves with dark margins; lesions may be covered in pink masses in favorable weather conditions.

Cause

Fungus

Comments

Favors warm, wet conditions; higher temperatures result in the development of more visible symptoms.

Management

Cabbage does not have high levels of resistance to blackleg and fungicides use is uneconomical; use disease free seed or treat with hot water to remove fungus prior to planting; remove and destroy crop debris after harvest or plow deeply into soil.

Category : Fungal, Oomycete

Downy mildew Peronospora parasitica

Downy mildew symptoms on cabbage leaf

Downy mildew symptoms on cabbage leaf

Symptoms

Irregular yellow patches on leaves which turn light brown in color; fluffy gray growth on the undersides of the leaves

Cause

Fungus

Comments

Disease emergence favored by cool, moist conditions

Management

Remove all crop debris after harvest; rotate with non-brassicas; application of appropriate fungicides may be required if symptoms of disease are present

Category : Viral 

Ring spot Mycosphaerella brassicicola

Symptoms
Small, purple spots surrounded by a ring of water-soaked tissue on leaves which mature to brown spots with olive green borders 1-2 cm across; spots may develop numerous fruiting bodies which give them a black appearance or develop a concentric pattern; heavily infected leaves may dry up and curl inwards
Cause
Fungus
Comments
Ring spot requires cool, moist conditions to survive; disease symptoms typically develop in the fall and the peak of the infection occurs in winter
Management

Refrain from planting in areas known to have had disease previously; rotate crop to non-brassicas; sanitize tools and equipment regularly; apply appropriate fungicide if disease is identified in crop

Category : Other

Slugs & snails (Gray garden slug, Spotted garden slug, Brown garden snail, European garden snail , etc.) Decoratus reticulatum
Limax maximus 
Helix aspersa 
Cornu aspersum

European brown snail

Gray garden slug

 

Symptoms
Irregularly shaped holes in leaves and stems; flowers and fruit may also be damaged if present; if infestation is severe, leaves may be shredded; slime trails present on rocks, walkways, soil and plant foliage; several slug and snail species are common garden pests; slugs are dark gray to black in color and can range in size from 2.5 to 10 cm (1-4 in); garden snails are generally smaller and possess a rounded or spiral shell
Cause
Mollusc
Comments
Slugs and snails prefer moist, shaded habitats and will shelter in weeds or organic trash; adults may deposit eggs in the soil throughout the season; damage to plants can be extensive
Management

Practice good garden sanitation by removing garden trash, weeds and plant debris to promote good air circulation and reduce moist habitat for slugs and snails; handpick slugs at night to decrease population; spread wood ashes or eggshells around plants; attract molluscs by leaving out organic matter such as lettuce or grapefruit skins, destroy any found feeding on lure; sink shallow dishes filled with beer into the soil to attract and drown the molluscs; chemical controls include ferrous phosphate for organic gardens and metaldehyde (e.g. Buggeta) and carbaryl (e.g Sevin bait) for non-organic growers.

Pests

Category : Insects

Beet armyworm Spodoptera exigua

Beet armyworm adult

Larva of beet armyworm

beet armyworm (Spodoptera exigua) larvae on soybean leaf

Beet armyworm larva

Beet armyworm eggs covered in white hairs

Young larvae

Symptoms
Singular, or closely grouped circular to irregularly shaped holes in foliage; heavy feeding by young larvae leads to skeletonized leaves; shallow, dry wounds on fruit; egg clusters of 50-150 eggs may be present on the leaves; egg clusters are covered in a whitish scale which gives the cluster a cottony or fuzzy appearance; young larvae are pale green to yellow in color while older larvae are generally darker green with a dark and light line running along the side of their body and a pink or yellow underside.
Cause
Insect
Comments
Insect can go through 3–5 generations a year.
Management

Organic methods of controlling the beet armyworm include biological control by natural enemies which parasitize the larvae and the application of Bacillus thuringiensis; there are chemicals available for commercial control but many that are available for the home garden do not provide adequate control of the larvae.

Cabbage aphid Brevicoryne brassicaea

Cabbage aphid colony on a cabbage leaf

Cabbage aphid adult

Aphid colony

Heavily infested leaf

Adult aphid

Multiple life stage

Heavy infestation of cabbage leaves

Dense colony

Lady beetles feeding on aphids

Large populations can cause stunted growth or even plant death; insects may be visible on the plant leaves and are small, grey-green in color and soft bodied and are covered with a white waxy coating; prefer to feed deep down in cabbage head and may be obscured by the leaves.
Cause
Insect
Comments
Cabbage aphids feed only on cruciferous plants but may survive on related weed species.
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.

Cabbage looper Trichoplusia ni 

Cabbage looper feeding on cabbage leaf

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

Management may be needed after cabbage heading; biological controls such as spraying with Bacillus thuringiensis can be effective at controlling looper numbers; application of appropriate insecticide after heading also controls looper populations; selective insecticides help to protect populations of natural enemies on crop

Cutworms Agrotis spp.
Peridroma saucia
Nephelodes minians
and others 

Cutworm larva severing plant stem

Cutworms will curl up into a characteristic C shape when disturbed

Cutworm feeding on plant stem

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
Insect
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

Diamondback moth Plutella xylostella

Larva feeding on cabbage leaf

Cabbage damaged by Diamondback moth larvae

Diamondback moth pupae

 

Symptoms
Young larvae feed between upper and lower leaf surface and may be visible when they emerge from small holes on the underside of the leaf; older larvae leave large, irregularly shaped shotholes on leaf undersides, leaving the upper surface intact; larvae may drop from the plant on silk threads if the leaf is disturbed; larvae are small (1 cm/0.3 in) and tapered at both ends; larvae have to prolegs at the rear end that are arranged in a distinctive V-shape
Cause
Insect
Comments
Larvae take between 10 and 14 days to mature and spin a loose, gauze-like cocoon on leaves or stems to pupate
Management

Larvae can be controlled organically by applications of Bacillus thurengiensis or Entrust; application of appropriate chemical insecticide is only necessary if larvae are damaging the growing tips of the plants

Flea beetle Phyllotreta spp.

Crucifer flea beetles and damage on cabbage leaf

 

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
Insect
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

Large cabbage white (Cabbageworm) Pieres rapae 

 

Cabbageworm and frass on a cabbage leaf

Cabbage damaged by cabbageworm

 

 

 

 

 

 

Symptoms
Large ragged holes in leaves or bored into head; green-brown frass (insect feces) on leaves; caterpillar is green in color and hairy, with a velvet-like appearance; may have faint yellow to orange stripes down back; slow-moving compared with other caterpillars
Cause
Insect
Comments
Butterfly larvae cause damage by feeding on plants; can be distinguished from other caterpillars by its sluggish movement; in large numbers larvae can cause extensive damage very quickly
Management

Plant can tolerate quite a lot of damage from caterpillars between transplanting and heading; hand pick caterpillars from plants and destroy; scrape eggs from leaves prior to hatching; apply appropriate insecticide if infestation is very heavy

Thrips (Western flower thrips, Onion thrips, etc) Frankliniella occidentalis
Thrips tabaci

Western flower thrips

 

 

 

 

 

 

 

 

 

Onion thrips on cabbage

 

 

 

 

 

 

 

 

 

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 several viruses including 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

Category : Nematodes

Root knot nematode Meloidogyne spp.

Symptoms
Galls on roots which can be up to 3.3 cm (1 in) in diameter but are usually smaller; reduction in plant vigor; yellowing plants which wilt in hot weather
Cause
Nematode
Comments
Galls can appear as quickly as a month prior to planting; nematodes prefer sandy soils and damage in areas of field or garden with this type of soil is most likely
Management

Plant resistant varieties if nematodes are known to be present in the soil ;check roots of plants mid-season or sooner if symptoms indicate nematodes; solarizing soil can reduce nematode populations in the soil and levels of inoculum of many other pathogens

 

 

 

 

پست های مرتبط