Prepared: March 2005
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Production Regions
The principal cabbage producing counties in Virginia are Accomack, Carroll, Hanover, Northampton, and Patrick.
Standard varieties recommended for early planting in Virginia include Charmont and Dynamo. Varieties recommended for midseason and late planting include Market Prize, Gourmet, and A&C #5. Variety selection depends on several factors, such as market acceptability, yield, and horticultural characteristics. Cabbage prefers to grow in sunny but cool temperatures (60-65°F). The soil should be rich and moist but well drained, with a pH of 5.5-6.5.
The early cabbage crop grows from transplants seeded at the rate of 1 oz. for 3,000 plants. Check with a seedsman to determine if seed is hot water treated. If not, soak seed at 122°F for 25 minutes. Transplants are ready for field planting four to six weeks after seeding. Storage of pulled, field-grown cabbage transplants should not exceed nine days at 32°F or five days at 66°F before planting in the field. Precision seeders can be used for direct seeding. However, seed should be sown 15 to 20 days before the normal transplant date for the same maturity date. Early varieties require 85 to 90 days from seeding to harvest, and main-season crops require 110 to 115 days. Transplants are set in rows 2 to 3 ft. apart. They are placed 9 to 15 inches apart in the row for early plantings and 9 to 18 inches apart for late plantings, depending on variety, fertility, and market use. Plant spacing will affect head size. Close spacing (12 inches apart in the row) produces small heads.
Cabbage grows from March to December and can withstand temperatures as low as 15°F to 20°F. Summer planting dates start around April 1 and continue through June 15. Harvesting begins around July 1 but is most active from July 15 to August 31 and ends September 15. Fall planting starts July 15 and continues through August 31 for the lower elevation areas in the state. Only a small amount of acreage in Carroll and Patrick county are planted for fall harvest due to possible freezes at higher elevations. Fall harvest begins October 15, but most active harvesting occurs November 15- December 15.
Cabbage is ready to harvest after 70-100 days and when the head becomes firm and mature. The size of the head will depend on variety, fertility, and spacing. Cabbage is harvested by bending the head over to one side and cutting the stem with a sharp knife as close to the head as possible. The head should not be broken or twisted off since this may damage it. Often, broken stalks are also more susceptible to decay. If the cabbage cannot be harvested at maturity, bend the head over to break part of the roots to reduce head splitting. Store the harvested cabbage in a very cold (32°F) and moist (95% relative humidity) environment for four to five months.
Worker Activities
During the growing season, worker activities in the field include seeding, transplanting (April-June), cultivating, scouting, spraying, occasional hand weeding, and harvesting (August-September for summer plantings and November-December for fall plantings). Strictly following re-entry intervals (REIs) should minimize any risk of exposure to pesticides during these activities. If workers are required to go back in the field before the proper time limit has expired then personal protective equipment (PPE) is worn. Activities that bring workers in direct contact with the plants during the growing season are generally limited to harvest time because the cabbage heads are hand picked by the workers.
Special Use Labels
Section 18 Emergency Use Exemption and Special Local Need 24(c) labels are used to supplement the chemical tools available to producers for pest control. Once the problem or gap in pest control has been identified, specialists submit the proper documentation for the Emergency Use/Special Local Need label. Thus far, Extension specialists have been successful in obtaining these labels. Special Local Need (SLN) labels in Virginia are granted by the Virginia Department of Agriculture and Consumer Services (VDACS) and are usually only valid for limited time intervals. Section 18 Emergency Use labels are evaluated and granted by the Environmental Protection Agency (EPA) and can be renewed annually. Without these temporary use labels, pest control in vegetable crops might be extremely difficult for producers.
Control recommendations found below were modified from information presented in the 2004 Commercial Vegetable Production Recommendations-Virginia 5, unless otherwise noted.
INSECTS 6
In general, the cabbage looper, imported cabbageworm, diamondback moth, and harlequin bug are the most economically important insect pests of cabbage in Virginia. Other minor pests include aphids and worm species such as the cross-striped cabbageworm, cabbage webworm, and fall and beet armyworms.
Aphids
Cabbage Aphid, Brevicoryne
brassicae
Green Peach Aphid, Myzus persicae
In general, aphids feed on plant sap, which may reduce plant vigor, size, and yield. The leaves can become distorted and curled. Also, as they feed on the underside of the leaves, aphids excrete honeydew. This, in turn, leads to the growth of black, sooty mold, which may block out sunlight and thus reduce plant yield, as well as market quality of the leaves. In addition, aphids can vector certain plant viruses.
Monitoring: If a systemic insecticide such as imidacloprid is not applied at planting, then aphid scouting is recommended. Check 20 to 40 plants per field, and treat when you find a localized infestation.
Chemical Control: Treat when aphids appear in damaging numbers. Thorough spray coverage beneath leaves is important. Narrow-spectrum insecticides for worm control, such as Bt products, indoxacarb, spinosad, and methoxyfenozide, will not control aphids. See the Chemical Insect Control section.
Biological Control: A number of natural enemies such as lady beetles (adults and larvae), lacewing larvae, syrphid larvae, parasitic wasps, and fungal pathogens will reduce aphid populations. Natural enemies will often keep aphid populations below damaging numbers and, therefore, should be considered before making an insecticide application. However, if the spread of virus is of concern, chemical treatment will be necessary.
Cultural Control: Plant disease-free certified seed. Avoid planting fields immediately downwind of a barrier such as hedgerows or woodlots, which reduce wind velocity and increase the number of dispersing aphids falling into fields. These barriers can also cause overfertilization with nitrogen, which results in lush growth attractive to aphids. Reflective foil mulches may reduce aphid colonization. Destroy crop debris as soon as possible after harvest.
Beet Armyworm, Spodoptera exigua
The beet armyworm (BAW) may be a sporadic pest of fall cabbage plantings in Virginia. Larvae are light green to dark olive green and sometimes have stripes of these colors down the back. There is usually a distinctive dark spot on each side just above the second pair of thoracic legs. The larvae feed gregariously, usually by skeletonizing foliage. As a leaf feeder, beet armyworm consumes much more cabbage tissue than the diamondback moth, but it is less damaging than the cabbage looper.
Monitoring: Before heading, treat when 20% or more of the plants are infested. If heads are already formed, then treat when 5% of the crop is infested.
Chemical Control: The BAW is one of the most difficult caterpillars to control because it has developed resistance to many commonly used insecticides. Treatment should be targeted toward young larvae. Thorough spray coverage is essential to control newly hatched worms. A three- to four-day spray interval may be necessary to bring moderate to heavy populations under control. Rotation of insecticides with different modes of action is recommended to reduce the development of resistance. Adding a spreader-sticker to the spray improves control. See the Chemical Insect Control section for more information.
Biological Control: Heavy precipitation will generally keep population levels in check. A number of parasitic wasps will attack beet armyworm larvae.
Cultural Control: Beet armyworm strongly prefers pigweed to other host plants. It will rapidly defoliate this weed and then move on to alternative crops. Thus, weed control will help to reduce BAW infestations.
Cabbage Looper, Trichoplusia ni
Cabbage loopers may be identified by their pale green color, thin white stripes down the back and sides, and their doubling-up or looping movement. These insects feed on the underside of leaves, producing ragged holes of various sizes. Feeding begins in late July or early August and usually continues through harvest. Several generations can occur during a year.
Monitoring: When 20% or more of the plants, before heading, are infested, begin spray treatment. If heads are already formed, then treat when 5% of the crop is infested.
Chemical Control: Thorough spray coverage is necessary to control cabbage looper. See the Chemical Insect Control section.
Biological Control: Several parasitic wasps and predators attack the cabbage looper (ex. Hyposoter, Copidosoma, and Trichogramma) as do general predators and viral diseases. Nuclear polyhedrosis virus (NPV) can substantially reduce population levels of larvae, especially after a rainy period.
Cultural Control: Plow under crop remnants in spring to bury overwintering pupae before the adults emerge. If possible, hand pick caterpillars off plants.
Cabbage Root Maggot, Delia radicum
Root maggots overwinter in the soil as larvae. The larvae are yellowish white and legless. The head end of the maggot is tapered, and the rear end is blunt. In late spring, the adults emerge and mate. The females deposit their eggs in soil crevices near the base of the plants. When the larvae hatch, they feed on the roots of the cabbage. Root maggots can be destructive in seedbeds and on young transplants. The larvae can bore into sprouting seeds and prevent development of plants. They will tunnel into roots and stems, causing rot. Eventually, the plants wilt and die.
Monitoring: There are no effective strategies to monitor fields except to examine the soil at the base of plants for tiny white eggs.
Chemical Control: Apply a registered insecticide broadcast, and work it into the soil immediately before seeding the seedbed or transplanting. Airblast sprayers are NOT recommended for maggot control. Note: For postplanting spray treatments, growers should be aware that when yellow rocket (mustard family) first blooms, cabbage maggot adults (flies) begin laying eggs on roots or in soil near roots. See the Chemical Insect Control section for more information.
Biological Control: Some ground beetles and rove beetles are predaceous on root maggots.
Cultural Control: Immediately after harvest, plow under crop debris to prevent use of plant remnants as overwintering sites. Root maggots prefer to lay their eggs in moist, organically rich soil, so avoid overfertilization with manure. Placing a sturdy material at the base of each transplant will prevent cabbage maggots from laying eggs around the stems. Spunbonded row covers can control cabbage maggots by excluding flies from laying eggs.
Cutworms
Black Cutworm, Agrotis
ipsilon
Variegated Cutworm, Peridroma
saucia
Granulate Cutworm, Feltia subterranea
Cutworms are sporadic pests of many crops. Several species of cutworm may be found in Virginia. Most are night feeders that hide under plant and soil debris common in weedy or minimum-tillage fields. Another distinguishing quality is their habit of rolling into a tight C-shape if disturbed. Newly hatched cutworm larvae feed on young plants at the soil line, often severing the stems.
Monitoring: Even if you use a preplant broadcast insecticide treatment, scout fields for cutworm damage within a week of planting or plant emergence. Cutworms are not typically seen in the open during the day; however, digging the soil around injured plants may reveal their presence. If cutworms are actively cutting plants, you may use a postplanting contact treatment.
Chemical Control: See the Chemical Insect Control section.
Biological Control: Cutworms are attacked by many ground-dwelling insect predators, especially carabid beetles. Also, pathogens such as Beauveria bassiana and entomopathogenic nematodes often will infect larvae.
Cultural Control: Proper tillage will help eliminate some species of cutworms that may move off of cover crops.
Diamondback Moth, Plutella xylostella
Diamondback moth larvae (DBM) are small, about 1/3 inch long when mature. They are green and tapered at each end. They wiggle rapidly when disturbed and often drop from the plant, hanging from a silken thread. The adults lay minute eggs on the underside of the leaves. After 10 to 14 days, the larvae hatch and bore into the leaves, feeding internally on leaf tissue. Larger larvae feed on the surface of the leaves, especially the undersides, and cause characteristic "window-like" feeding damage. In Virginia, the adult moths overwinter in cabbage debris.
Monitoring: When 20% or more of the plants (before heading) are infested, begin spray treatment. If heads are already formed, then treat when 5% of the crop is infested.
Chemical Control: Rotating insecticides with different modes of action is recommended to reduce the development of resistance. Treat with a registered insecticide every four days after first true leaves appear until harvest if worms are present. Direct the insecticide to the undersides of the leaves to control newly hatched worms. Adding a spreader-sticker in the spray improves control. Several of the insecticides listed for use against DBM may no longer be effective in certain areas due to DBM resistance. Consult your local county Extension office for the most effective control. See the Chemical Insect Control section for more information.
Biological Control: Several species of parasitic wasps attack this pest, and parasitism may be as high as 95% some years. Use of narrow-spectrum (lepidopteran-specific) insecticides will help conserve these beneficial insects.
Cultural Control: Plow under crop debris, and destroy mustard-type weeds several weeks before planting.
Flea Beetles, Phyllotreta spp.
Flea beetles are small, shiny, hard beetles with enlarged hind legs that allow them to jump like fleas. The adults overwinter in the soil, and in early spring they begin to feed on crop foliage. Both the larvae and adult feed on cabbage leaves. However, it is the adult that causes the most damage by chewing multiple, tiny "shot-holes" on the undersides of the leaves. Young plants, especially transplants, can be severely damaged.
Monitoring: Check newly emerged seedlings twice weekly for flea beetle damage until plants are well established. Relatively low populations can cause economic damage when plants are in early leaf stages. Treat if you find several damaged rows; spot treatment of outside rows or borders may be sufficient.
Chemical Control: See the Chemical Insect Control section.
Biological Control: No current recommendations for commercial production.
Cultural Control: Plow under weed and crop debris in the fall after harvest.
Harlequin Bugs, Murgantia histrionica
Harlequin bug adults are black with reddish orange and yellow markings, flat, shield shaped, and about 3/8 inch in length. The nymphs resemble the adults but are smaller and wingless. Both adults and nymphs cause damage with their piercing/sucking mouthparts by sucking sap from the plant. This feeding causes yellow or white blotches to appear on leaves. The plants eventually wilt, turn brown, and die. Adults overwinter in plant debris and emerge in early spring to feed and lay eggs. Multiple generations occur annually in Virginia.
Monitoring: Controls should be implemented if one bug per 10 plants is found.
Chemical Control: See the Chemical Insect Control section.
Biological Control: Harlequin bug eggs are parasitized by several different species of parasitic wasps-most importantly, Trissolcus spp.
Cultural Control: Conduct a thorough postharvest cleanup, being careful to remove all plant debris. In early spring, eliminate weedy areas around the garden.
Imported Cabbageworm, Pieris rapae
The imported cabbageworm larvae are velvety green with faint yellow longitudinal stripes and many fine hairs. Damage is caused when the larvae feed on the underside of the leaves, producing ragged holes. Then, larvae bore into the heads to continue to feed. If controls for other worm pests are being applied, then the imported cabbageworm is usually not an economic pest of cabbage in Virginia.
Monitoring: When 20% or more of the plants (before heading) are infested, begin spray treatment. If heads are already formed, then treat when 5% of the crop is infested.
Chemical Control: Rotating insecticides with different modes of action is recommended to reduce the development of resistance. Thorough spray coverage is essential to control newly hatched worms. Adding a spreader-sticker to the spray improves control. See the Chemical Insect Control section for more information.
Biological Control: A parasitic wasp, Trichogramma spp., attacks imported cabbageworm eggs. Mass releases of Trichogramma spp. may successfully reduce pest populations. Several other parasites attack pupae and larvae. The braconid wasp Apanteles glomeratus is most effective. Natural control by viruses and bacterial disease occur as well.
Cultural Control: Conduct a thorough postharvest cleanup where the imported cabbageworm has been a problem in the previous year.
Thrips, Thrips tabaci
Adults and immatures cause damage by puncturing and rasping the outer leaf tissue and sucking the juices from the plant. White blotches appear on leaves, and the tips of leaves wither and turn brown. This damage tends to lead to a cosmetic problem rather than to a reduction in yield. Excessive damage may make the heads unacceptable for fresh market and processing cabbage. These small adults are yellowish or brownish with wings. The nymphs are white, wingless, and look like small adults. The adults and nymphs overwinter in plant debris in or near the fields. They emerge in the spring to lay eggs in incisions made in plant tissue. Multiple overlapping generations occur annually in Virginia.
Monitoring: Controls are not recommended unless you observe heavy populations.
Chemical Control: When thrips are increasing in cabbage fields, it is important to apply insecticides before cupping or curd formation. See the Chemical Insect Control section for more information.
Biological Control: Minute pirate bugs and some lady beetles are predators of thrips.
Cultural Control: Field observations indicate that the variety Market Prize may be more attractive to thrips than other varieties. If possible, avoid planting cabbage immediately downwind of small grains or alfalfa.
Chemical Insect Control
The list below contains all of the products available to producers for insect control in cabbage along with the recommended application rates. Always consult the label before making an application. PHI = Pre-Harvest Interval. REI = Re-Entry Interval.
Control recommendations found below were modified from information presented in the 2004 Commercial Vegetable Production Recommendations-Virginia.7
DISEASES
Disease in cabbage can slow down development and injure the leaves, greatly reducing the yield and making the crop less profitable. Each of the diseases listed below occurs within Virginia and depends primarily on weather conditions but also on several other factors. These factors include site location, seed quality, and effective management procedures. Good sanitation and management practices are key to a successful disease-control program. Diseases most frequently seen affecting cabbage in Virginia are alternaria leaf spot and downy mildew.
Alternaria Leaf Spot, Alternaria brassicae
Alternaria leaf spot attacks the oldest leaves on the cabbage. Symptoms show up as round, concentric-ringed lesions varying in size from specks to an inch or more in diameter and gray-brown in color. It is primarily a seed-borne fungus, and the spores colonize the seed coat during seed development. The fungus becomes active when the seed germinates. It develops slowly and is usually not detected until leaf spots appear on the plants in the field. The disease is most prevalent during warm, wet weather. Once sporulation occurs, the spores are easily spread by wind and splashing rain.
Monitoring: Inspect the plants frequently for small, dark spots on the leaf surface. Monitoring your crop on a regular basis for disease will help you apply pesticides when needed.
Chemical Control: Use recommended fungicides at the first sign of disease, and continue every seven to ten days. Boscalid (Endura) is a new fungicide recently labeled for control of this disease. It would be a good fungicide to alternate with azoxystrobin (Amistar) for resistance management. See the Chemical Disease Control section for more information.
Biological Control: No commercially effective controls are available.
Cultural Control: Eliminate cruciferous weeds, and rotate out with noncruciferous crops. Request hot water processed seed. After harvest, plow under or burn any crop debris left in the field.
Black Rot, Xanthomonas campestris
Blackleg, Phoma lingam
Black rot is spread by a bacterium that travels through the vascular system of the leaf and stem. The disease is recognized easily by large yellow to yellow-orange "V-shaped" areas extending inward from the margin of a leaf and by black veins in the infected area. It causes the most damage in wet, warm weather and spreads easily. The bacteria can survive in the soil for a year and may be spread in surface water or through irrigation.
Blackleg overwinters on crop debris or infected seed. Early symptoms appear on the stem near the soil line as elongated, sunken, tan lesions. Gradually, the lesions become well defined and circular. They have gray-brown centers with many black dots, smaller than a pinhead and scattered irregularly. The stem may be girdled as the disease progresses, resulting in the wilting and death of the plant. The roots may also become infected. Symptoms of root infections are evident in sudden wilting.
Monitoring: For black rot - carefully check for the yellow leaf margins typical of black rot. These occur most often in the oldest leaves, especially after rain. For blackleg - check for lesions at the base of stems. On blackleg-infected plants, wilted leaves tend to remain attached to the stem instead of defoliating like plants infected with yellows or black rot.
Chemical Control: Fixed copper sprays will help reduce spread of black rot if treatments begin when disease first become evident. See the Chemical Disease Control section for more information.
Biological Control: No commercially effective controls are available.
Cultural Control: Use hot water seed treatment, and choose varieties resistant to black rot (ex. A&C #5) when available. Clean up, burn, or plow down all crop debris immediately after harvest. Rotate crops to allow two years between cole crop plantings for black rot control and four years between cole crop plantings for blackleg control.
Clubroot, Plasmodiophora brassicae
Clubroot is first identified by a decline of the plant, including yellowing of leaves and a tendency to wilt during hot days. An examination of the roots will reveal swollen, club-shaped roots instead of the normal fine network of roots. Infested fields remain unsuitable for production of cabbage and related crops for many years. Moreover, the fungus has a history of spreading to other fields in the community. Using irrigation water that contains fungal spores is one of the principal ways the disease is spread to new fields. Another way is using contaminated transplants.
Monitoring: Check for plants that become stunted and look wilted during sunny days. Usually, the disease first appears in the field in scattered groups. The disease intensity is more severe if soils are wet during and after transplanting or seeding.
Chemical Control: Terraclor 75WP is recommended; however, do not use the Terraclor 2EC formulation. See the Chemical Disease Control section for more information.
Biological Control: No commercially effective controls are available.
Cultural Control: If clubroot occurs, clean and disinfect any equipment to be used in other fields to prevent spread. Soil pH can be adjusted with hydrated lime to as close to seven as possible. Improve the drainage in the field by making ditches or other devices, and grow the crop on raised beds.
Damping-Off, Rhizoctonia solani
This disease causes young seedlings to wilt and die, or to not emerge at all. Stems of young seedlings become light brown and water-soaked near the soil line. Affected seedlings quickly wilt, topple over, and die. Generally, this disease is most effective at low temperatures and during wet weather or high humidity.
Monitoring: Check the stems of seedlings that are stunted or wilting. Generally, you will need to apply fungicides to control this disease.
Chemical Control: To protect against all damping-off pathogens, seeds are usually treated with broad-spectrum contact fungicides. Terraclor banded over the row after seeding can also be used. See the Chemical Disease Control section for more information.
Biological Control: No commercially effective controls are available.
Cultural Control: Practices that promote healthy seedlings can prevent or reduce the disease. Because damping-off is so difficult to contain, however, it is best to avoid it altogether.
Downy Mildew, Peronospora parasitica
Downy mildew is most prevalent at low temperatures and during wet weather or high humidity. Spores are primarily spread by wind and splashing rain. Symptoms appear on the surface of the cabbage heads. Many sunken black spots appear, ranging in size from necrotic flecks to 2 cm in diameter, with little or no sporulation. Infections on the cabbage will result in a purplish tinge and can predispose the plant to further bacteria that can rot tissue in the field or after harvest.
Monitoring: Scout fields for disease incidence during periods of cool (less than 75°F), wet weather. Check leaves closely and frequently for symptoms when weather conditions are conducive to disease development.
Chemical Control: Begin sprays when disease occurrence is predicted for the region. Use chlorothalonil or maneb every seven days. Apply other effective fungicides, such as aluminum tris (Aliette) and mefenoxam (Ridomil Gold/Bravo), every 14 days. Apply the first two mentioned on alternate weeks when using these fungicides. See the Chemical Disease Control section for more information.
Biological Control: No commercially effective controls are available.
Cultural Control: Practice a two-year crop rotation with noncrucifers. It is important to promote healthy, vigorous growth and a good nutritional program in the crop, as plants under nutritional stress are more susceptible to the disease. Also, avoid overhead irrigation.
White Mold, Sclerotinia sclerotiorum
In cabbage, infection can occur on the stem at the soil line, on the leaves at the base, or where the foliage comes in contact with the soil. The infections begin as tan, water-soaked, circular areas, which soon become covered by white, cottony fungal growth and may cover the entire head. Hard, black sclerotia develop in the white mycelial growth. The tissue becomes soft and watery as the disease progresses, destroying the head of cabbage. This disease favors cool, moist conditions and is most prevalent in cabbage with restricted air circulation.
Monitoring: Check the base of the stems of stunted or wilted plants for white fungal growth and hard black sclerotia. Monitor the crop carefully after long periods of wet weather.
Chemical Control: Endura is a new fungicide that may be applied two times during a season. Applications may be needed during wet weather when the soil remains wet for extended periods of time. See the Chemical Disease Control section for more information.
Biological Control: No commercially effective controls are available.
Cultural Control: Growers can successfully manage white mold on cabbage by combining cultural practices that discourage disease development. Plant cabbage in areas that promote good air circulation and drying of plant and soil surfaces. Fields with a history of white mold should be planted with nonsusceptible crops such as grains.
Yellows, Fusarium oxysporum conglutinans
Symptoms of Fusarium yellows are often confused with those of black rot. Both diseases cause leaf drop, curving stalks, and the formation of buds on leafless stems. The first and most striking symptom of yellows is the dull yellow to yellowish green appearance of affected leaves. However, the symptoms are often more noticeable on one side of the plant. Over time, the yellow turns brown and becomes dry and brittle. A microscopic examination may be necessary to distinguish yellows from black rot. The fungus can live in the soil for several years without being associated with any plant parts. Once the pathogen becomes established in the field, it is easily spread by rain and by equipment. The fungus enters the plant through the root hairs, and the spores are produced inside and outside the affected stems.
Monitoring: Plants will develop characteristic symptoms two to four weeks after transplanting. The speed of progress of yellows in the plant depends upon the degree of variety susceptibility and the soil temperature. Plants of some varieties growing in 75°F-85°F soils may die within two weeks. Others may continue to decline throughout the season, die slowly, or even produce a poor head. If soil temperatures decline after infection, the plant may merely lose a few yellow leaves, recover, and make a normal head.8 Send suspicious plants to a local disease identification clinic to assay the presence of the disease in the field.
Chemical Control: No effective chemical controls are available at this time.
Biological Control: No commercially effective controls are available.
Cultural Control: Resistant varieties like Charmant, Market Prize, Gourmet, and A&C#5 are the most recommended method of control against the disease. Due to the long life of the fungus in the soil, the conventional methods of crop rotation, seed treatment, fungicide sprays, and destruction of crop debris after harvest are of little value once the fungus is established in a specific field.
Chemical Disease Control
The list below contains all of the products available to producers for disease control in cabbage along with the recommended application rates of these chemicals. Always consult the label before making an application. PHI = Pre-Harvest Interval. REI = Re-Entry Interval.
Control recommendations were taken from 2004 Commercial Vegetable Production Recommendations-Virginia.9
NEMATODES
Root-knot nematodes (Meloidogyne spp.) are the most important species of nematode affecting cabbage in Virginia.10 These nematodes restrict water and nutrient uptake, giving the plant a stunted, wilted appearance. The diagnostic feature of root-knot nematode infection is the presence of galls on roots of affected plants. Severely affected plants may have galls as large as 1 inch in diameter. Nematode problems can be magnified by hot, dry summers. Symptoms and damage can mimic other diseases and pests, making identification nearly impossible to determine on site. Soil and root samples should be collected and analyzed by an expert.
Monitoring: Both diagnostic and predictive nematode assay programs in Virginia provide data to producers on the numbers and kinds of nematodes in soil along with recommendations for control. Soil samples for diagnostic assays are processed without charge to determine the cause of production problems during the growing season. Predictive nematode assays are done on samples collected after harvest.
Chemical Control: When using soil fumigation, it is important to sufficiently prepare the fields for planting. All crop debris and clods should be removed, and soil moisture should be adequate. Otherwise, soil fumigation will not be effective because the gaseous fumigant has not penetrated all soil particles. It is also necessary to allow an aeration period between fumigant applications and planting. Otherwise, crop injury will occur. For recommendations, see the Chemical Nematode Control section below.
Biological Control: No commercially effective controls are available.
Cultural Control: Sanitation and good cultural practices are the best preventive measures against nematodes. Examples include obtaining nematode-free roots and washing soil from machinery and tools before using them at different locations. Crop rotation with nonhost crops to lower their population size is highly recommended in the event of nematode activity.
Chemical Nematode Control11
Several chemicals are currently available for nematode control, although this may change in the next few years. Currently, the multipurpose soil fumigants chloropicrin, chloropicrin and dichloropropene (Telone C-17, Telone C-35), metam-potassium (K-PAM HL), metam-sodium (Vapam HL), and methyl bromide (Terr-O-Gas 67, MC-33) are recommended for use in Virginia. In addition, dichloropropene (Telone II) is a soil fumigant used only for nematodes. The nonfumigant nematicide, fenamiphos (Nemacur 15G), is also recommended for use in cabbage. Typically, chemical controls are used only when cultural practices cannot provide adequate control. However, these chemicals are still important tools when other control methods have failed.
Control recommendations were taken from 2004 Commercial Vegetable Production Recommendations-Virginia.12
WEEDS
The herbicides currently labeled for weed control in cabbage work on annual grasses, certain perennial grasses, and certain broadleaf weeds. However, producers in Virginia are faced with many additional broadleaf weed problems, including common lambsquarters, common purslane, pigweed species, and galinsoga. Yellow nutsedge is also a problem for many growers. If not controlled, weeds can greatly reduce root quality and may interfere with the harvest. Successful weed management is vital to the production of quality cabbage. Weeds compete with the crop for light, space, nutrients, and particularly water. Weed growth promotes disease problems and can harbor deleterious insects and diseases. Weeds also impair the ability to harvest effectively, reducing the quantity of marketable vegetables and increasing labor costs.
Monitoring: Proper weed identification is an important part of effective weed control. Weeds observed in previous crops within a given field should be noted to aid in future herbicide decisions. It is also important to monitor the effectiveness of preplant incorporated and preemergent herbicides once the crop emerges.
Chemical Control: To provide additional pest control, a Special Local Need 24(c) label has been approved in Virginia for the preemergence use of s-metolachlor (Dual Magnum 7.62E) and postharvest use of paraquat (Gramoxone Max 3SC). Recommended rates can be found in the Chemical Weed Control section below.
Biological Control: No commercially effective controls are available.
Cultural Control: Cultivation is a very important part of weed control. Weeds will outcompete a crop for nutrients, water, and sunlight, reducing yield and making the crop less profitable. Mechanical cultivation provides very effective weed control but is limited to small weeds that can be easily uprooted or covered. Incorporating cultivation with herbicides is the most cost-effective way to combat weeds and to produce a high yield. Crop rotation is also important to prevent domination of any one weed species year after year. Also, avoid fields with a history of severe weed infestations.
Chemical Weed Control
The list below contains all of the fully labeled products available to producers for weed control in cabbage along with the recommended application rates of these chemicals. Always consult the label before making an application. PHI = Pre-Harvest Interval. REI = Re-Entry Interval.
Preplant / Preplant Incorporated:
Preemergence:
Postemergence:
Postharvest:
Table 1: Effectiveness of herbicides recommended for weed control in cabbage.13
Developed and Written by:
Therese N. Schooley
Project Manager
Virginia Polytechnic
Institute and State University
Department of Entomology
Virginia Tech
Pesticide Programs (0409)
34 Agnew Hall
Blacksburg, VA 24061
Ph:
540-231-2086
Fax: 540-231-3057
E-mail: tschooley@vt.edu
Collaborating Authors:
Diseases:
Christine M. Waldenmaier
Research Specialist,
Plant Pathology
Virginia Polytechnic Institute and State
University
Eastern Shore Agricultural Research and Extension Center
(0512)
33446 Research Drive
Painter, VA 23420-2827
Ph:
757-414-0724
Fax: 757-414-0730
E-mail: cwalden@vt.edu
Insects:
Thomas P. Kuhar
Assistant Professor,
Entomology
Virginia Polytechnic Institute and State University
Eastern
Shore Agricultural Research and Extension Center (0512)
33446 Research
Drive
Painter, VA 23420-2827
Ph: 757-414-0724
Fax:
757-414-0730
E-mail: tkuhar@vt.edu
Pesticides:
Michael J. Weaver
Professor and Extension
Pesticide Coordinator
Virginia Polytechnic Institute and State
University
Department of Entomology
Virginia Tech Pesticide Programs
(0409)
34 Agnew Hall
Blacksburg, VA 24061
Ph: 540-231-6543
Fax:
540-231-3057
E-mail: mweaver@vt.edu
Weeds:
Henry P. Wilson
Professor, Weed
Science
Virginia Polytechnic Institute and State University
Eastern Shore
Agricultural Research and Extension Center (0512)
33446 Research
Drive
Painter, VA 23420-2827
Ph: 757-414-0724
Fax:
757-414-0730
E-mail: hwilson@vt.edu
Cultural Practices:
Rikki Sterrett
Associate
Professor, Horticulture
Virginia Polytechnic Institute and State
University
Eastern Shore Agricultural Research and Extension Center
(0512)
33446 Research Drive
Painter, VA 23420-2827
Ph:
757-414-0724
Fax: 757-414-0730
E-mail: mailto:vators@vt.edu
Edited by:
Susan E. Nessler
Project Manager
Virginia
Polytechnic Institute and State University
Department of
Entomology
Virginia Tech Pesticide Programs (0409)
34 Agnew Hall
Blacksburg, VA 24061
Ph: 540-231-8956
Fax: 540-231-3057
E-mail: snessler@vt.edu
On-Line Resources
C&P Press Online Crop Protection Reference
http://www.greenbook.net/free.asp
Crop Data Management Systems - Pesticide Labels
http://www.cdms.net/pfa/LUpdateMsg.asp
Insects and Related Pests of Vegetables
http://ipmwww.ncsu.edu/AG295/html
Pests of Vegetables and Fruit Trees
http://everest.ento.vt.edu/~idlab/vegpests/vegfact.html
Virginia Agricultural Statistics Service
http://www.nass.usda.gov/va/
Virginia Tech Pesticide Programs
http://www.vtpp.ext.vt.edu/
Virginia Tech Weed Identification Guide
http://www.ppws.vt.edu/weedindex.htm
1 Virginia Agricultural Statistics Bulletin and Resource Directory, 2001. Virginia Agricultural Statistics Service, Richmond, Virginia. Bulletin 77 (pp. 6, 54).
2 Bratsch, A. D., Kuhar, T. P., Phillips, S. B., Sterrett, S. B., Waldenmaier, C., and Wilson, H. P., 2004. Commercial Vegetable Production Recommendations (No. 456-420), Virginia Cooperative Extension, (pp. F12-F13).
3 Relf, D., and McDaniel, A., "Cole Crops or Brassicas," June 2000. Virginia Cooperative Extension Publication No. 426-403. http://www.ext.vt.edu/pubs/envirohort/426-403/426-403.html#3
4 Swaider, J. M., Ware, G. W., and McCollum, J. P., 1980. Producing Vegetable Crops (4th ed.). Interstate Publishers, Inc. Danville, IL.
5 Bratsch, A. D., Kuhar, T. P., Phillips, S. B., Sterrett, S. B., Waldenmaier, C., and Wilson, H. P., 2004. Commercial Vegetable Production Recommendations (No. 456-420), Virginia Cooperative Extension (pp. F14-F15, F17).
6 Capinera, J. L., 2001. Handbook of Vegetable Pests. Academic Press, San Diego, CA.
7 Bratsch, A. D., Kuhar, T. P., Phillips, S. B., Sterrett, S. B., Waldenmaier, C., and Wilson, H. P., 2004. Commercial Vegetable Production Recommendations (No. 456-420), Virginia Cooperative Extension (pp. F16-F17).
8 Cornell University, Department of Plant Pathology. Vegetable MD Online, Fact Sheet (p. 730.10). http://vegetablemdonline.ppath.cornell.edu/factsheets/Crucifers_Fusarium.htm.
9 Bratsch, A. D., Kuhar, T. P., Phillips, S. B., Sterrett, S. B., Waldenmaier, C., and Wilson, H. P., 2004. Commercial Vegetable Production Recommendations (No. 456-420), Virginia Cooperative Extension (p. F15).
10 Eisenback, J. D., Professor. Virginia Tech Department of Plant Pathology, Physiology, and Weed Science. Communications via email, September 6, 2003.
11 Bratsch, A. D., Kuhar, T. P., Phillips, S. B., Sterrett, S. B., Waldenmaier, C., and Wilson, H. P., 2004. Commercial Vegetable Production Recommendations (No. 456-420), Virginia Cooperative Extension (pp. E6-E7).
12 Bratsch, A. D., Kuhar, T. P., Phillips, S. B., Sterrett, S. B., Waldenmaier, C., and Wilson, H. P., 2004. Commercial Vegetable Production Recommendations (No. 456-420), Virginia Cooperative Extension (pp. F13-F14).
13 Bratsch, A. D., Kuhar, T. P., Phillips, S. B., Sterrett, S. B., Waldenmaier, C., and Wilson, H. P., 2004. Commercial Vegetable Production Recommendations (No. 456-420), Virginia Cooperative Extension (pp. E8-E13).