Commercial Production and Management of Cabbage and Leafy Greens Reviewed by Timothy Coolong, Extension Horticulturist Table of Contents History, Utilization and Botany .........................................................................................................................3 William Terry Kelley and Darbie M. Granberry Culture and Variety Selection............................................................................................................................4 William Terry Kelley and George E. Boyhan Soil and Fertilizer Management ........................................................................................................................8 Darbie M. Granberry, William Terry Kelley and George E. Boyhan Cabbage Disease Management........................................................................................................................13 David B. Langston, Jr. Insect Management..........................................................................................................................................18 David B. Adams Weed Management...........................................................................................................................................27 Greg MacDonald Sprayers............................................................................................................................................................28 Paul E. Sumner Irrigation ..........................................................................................................................................................31 Anthony W. Tyson and Kerry A. Harrison Harvest and Handling ......................................................................................................................................32 William C. Hurst Production Costs..............................................................................................................................................36 George O. Westberry Marketing Cabbage and Leafy Greens............................................................................................................40 William O. Mizelle, Jr. Edited by WilliamTerry Kelley, Extension Horticulturist; Greg MacDonald, Former Extension Weed Scientist; and David B. Adams, Extension Entomologist Commercial Production and Management of Cabbage and Leafy Greens 1 Foreword This publication is the result of a joint effort among the seven disciplines in the University of Georgia College of Agricultural and Environmental Sciences that serve the Georgia vegetable industry. The 11 topics covered in this bulletin are all integral parts of a suc- cessful cabbage/leafy greens management program. Each topic focuses on a particular aspect of production and provides information on the latest management technology for that phase of production. The authors hope that the information contained in this publication will assist growers in improving profitability. Chemical pest control recommendations are subject to change from year to year; thus, only general pest control guide- lines are mentioned in this publication. Growers are urged to consult the current Georgia Pest Control Handbook or check with their local county Extension agent regarding the most recent chemical recommenda- tions. Mention of tradenames in this publication is nei- ther an endorsement of a particular product nor a lack of endorsement for similar products. 2 Commercial Production and Management of Cabbage and Leafy Greens History, Utilization and Botany William Terry Kelley and Darbie M. Granberry, Extension Horticulturists Cabbage and leafy greens, including turnip, mus- Mustard originated in central and eastern Asia, the tard, kale and collard, have a long history of produc- Mediterranean and the Himalayas. tion in Georgia. The cabbage and leafy greens indus- Uses of cabbage and leafy greens vary widely. All try makes up almost 20 percent of the Georgia veg- are grown for both the fresh market and processing etable industry’s acreage, with almost 30,000 acres into any number of products. Cabbage is popular as a under production in a given year. The nature of the fresh item used in slaw, cooked or processed into pre- industry has changed, however, with more emphasis served products such as sauerkraut. Kale is used pri- on shipping and less on locally marketed product. The marily as a garnish because of its attractive curly bulk of all these crops remains in the fresh market, leaves. However, kale can be cooked and eaten in with a growing segment of processed greens. much the same fashion as other leafy greens. Collard, The botanical classifications of several types of turnip greens and mustard are used primarily as cabbage and leafy greens grown in Georgia are listed cooked fresh vegetables. However, the tendency to in Table 1. Brassica oleracea includes all cabbage, find them served in a raw form is increasing. All are collard and kale. This group has long been referred to grown for the fresh market but also are grown widely collectively as “cole crops.” This term comes from a for processing both as canned and frozen products. Middle English or Norse word that originated from Collard, kale, turnip and cabbage are dicotyledo- the Latin word caulis, which refers to the cabbage nous herbaceous plants that are biennial in nature, stem or stalk. Wild types of these crops have been although the wild form of cabbage is an annual. All found along the Atlantic Coast of Europe and cab- are grown commercially as annuals, however. Kale, bage, kale and collard are believed to have originated turnip and collard do not form a head; all have a in Western Europe. Early uses of these crops were for rosette form of vegetative growth on a short stem. medicinal purposes. Collard produces a large smooth leaf, and turnip pro- Kale is thought to be the first form to be domesti- duces smaller leaves that are generally pubescent. cated and may have been cultivated as early as 2000 Newer varieties of turnip may be smooth-leaved and BC. Hard-headed types of cabbage were not cultivated are more similar in appearance to mustard. Mustard is until around the ninth century. Traders and explorers a cool-season annual that also forms a rosette of vege- spread the crops to other parts of the world, where tative growth. Mustard leaves may be curly or smooth they were quickly adopted as cultivated crops. depending on the cultivar. Cabbage forms a head as Although cabbage is not particularly high in protein, the leaves mature and become densely packed. vitamins and minerals, kale is one of the most nutri- Cabbage and leafy greens are all produced for tious vegetables grown, based on fresh weight. their leaves. Some types of turnip also produce a Table 1. Botanical classification of several types of cabbage and leafy greens Common Name Genus Species Group Subgroup Green Cabbage Brassica oleracea Capitata Alba Red Cabbage Rubra Savoy Cabbage Sabauda Kale Acephala none Collard none Mustard juncea Pervirdis none Turnip rapa Rapifera none Commercial Production and Management of Cabbage and Leafy Greens 3 fleshy root harvested for consumption. These roots usually occurs after an extended period of exposure to can vary in shape from flat-round to elongated to low temperatures (below 50°F) followed by a period of spherical. The outer color may be totally white or warmer temperatures. Exposure to temperatures below have shades of red or purple, particularly at the shoul- 40°F or above 70°F after low temperature exposure der. Cabbage, collard and kale are hard to distinguish causes rapid emergence of the seed stem. Losses to from one another at the seedling stage but soon devel- bolting in these crops occur almost every year, particu- op recognizable characteristics. larly in overwintered crops that are exposed to severe All of these crops may be subject to bolting (pre- temperatures. The flowers of the crops are whitish or mature appearance of a flower/seed stem). Flowering yellow and are pollinated by insects. Culture and Variety Selection William Terry Kelley and George E. Boyhan, Extension Horticulturists Climatic Requirements transplants, growers should always buy Georgia-certi- fied plants from reputable growers. Cabbage and leafy greens are adapted to a wide Producers of containerized plants specialize in range of environmental conditions and are grown growing plants in greenhouses that are designed specifi- throughout Georgia. Although the southwestern portion cally for the production of transplants. To contract with of the state produces the most, several areas contribute a grower for transplants, specify the cell size desired, significantly, including the southeast and the northeast. the variety to be planted and a specific delivery date of Cabbage, collard and kale can tolerate hard frosts, but the plants. severe freezes can be damaging. Turnip and mustard can Also, determine whether the plant grower or the tolerate fairly cold temperatures, but hard frosts can kill greens grower is to furnish the seed. The cost to the the crops or make them unmarketable. All can be grown grower for this type of transplant will vary depending on a wide range of soil types and are somewhat drought on the volume ordered and the cell size of the tray. tolerant, although production without irrigation is not Growing containerized transplants is a highly skilled, recommended. intensive operation that is usually not economically fea- Most production of cabbage and leafy greens occurs sible for the greens producer. in the spring, fall