Jerusalem Artichoke

D.R. Cosgrove1, E.A. Oelke2, J.D. Doll3, D.W. Davis2, D.J. Undersander>3, and E.S. Oplinger3

1 Department of Plant and Earth Sciences, University of Wisconsin - River Falls, WI 54022.

2Departments of Agronomy and Plant Genetics and Horticulture, University of Minnesota, St. Paul, MN 55108.

3Departinents of Agronomy and Soil Science, College of Agriculture and Life Sciences and Cooperative Extension Service, University of Wisconsin-Madison, WI 53706. March, 1991.

I. History:

Jerusalem artichoke (Helianthus tuberosus L.) is familiar to many as a weed, but has some potential as a crop plant. Native to the central regions of North America, the plant can be grown successfully throughout the U.S. under a variety of temperature and rainfall regimes. Several North American Indian tribes used Jerusalem artichoke as food prior to the arrival of European settlers. The explorer Champlain took Jerusalem artichokes from North America to France in 1605. By the mid 1600s it was widely used as a human food and livestock feed there.

In France, the artichoke is called "topinambour," although the word "Jerusalem" has several explanations. The artichoke became a staple food for North American pilgrims and was thought of as a new feed in a "new Jerusalem." A second theory is that the word Jerusalem is a twisting of the Italian word for sunflower-girasol. One additional explanation involves a 17th century gardener named Petrus Hondins of Ter-Heusen, Holland who was known to distribute his artichoke apples throughout Europe. Ter-Heusen was modified to Jerusalem in the United States. In recent years the fresh tubers have been widely marketed in the U.S., but in quite limited quantities.

II. Uses:

The plant can be grown for human consumption, alcohol production, fructose production and livestock feed.

A. Human Food:

Similar to water chestnuts in taste, the traditional use of the tuber is as a gourmet vegetable. Jerusalem artichoke tubers resemble potatoes except the carbohydrates composing 75 to 80% of the tubers are in the form of inulin rather than starch. Once the tubers are stored in the ground or refrigerated, the inulin is converted to fructose and the tubers develop a much sweeter taste. Dehydrated and ground tubers can be stored for long periods without protein and sugar deterioration. Tubers can be prepared in ways similar to potatoes. In addition, they can be eaten raw, or made into flour, or pickled. They are available commercially under several names, including sunchokes and lambchokes.

B. Alcohol Production:

In France the artichoke has been used for wine and beer production for many years. Ethanol and butanol, two fuel grade alcohols, can be produced from Jerusalem artichokes. The cost of producing ethanol currently is not competitive with gasoline prices, and therefore the success of ethanol plants has been limited.

C. Fructose Production:

About 50% of the 12 million tons of sugar consumed annually by Americans is grown and produced in the United States. Fructose is more soluble in water than sucrose, so fructose provides a more desirable syrup. In addition, it is 1.5 times sweeter than sucrose and can be consumed safely by diabetics.

The majority of domestically produced fructose is obtained from corn. Although the Jerusalem artichoke is a viable fructose source, the U.S. sugar industry has been hesitant in utilizing it because farmers have been concerried with its potential as a weed problem, and because it requires extra planting and harvesting equipment along with storage difficulties.

D. Forage Production:

The quality of artichoke tops make them a suitable livestock feed, but the forage quality has no advantage over other forage crops and should be classified as a maintenance feed. Both crude protein and digestible protein concentrations are low when compared with alfalfa (Table 1). Artichoke tops are superior in TDN to the perennial forages listed, but it has less TDN than corn silage.

Optimal forage quality can be obtained by harvesting tops during mid September when protein levels will be at their maximum. However, tuber yields will be reduced at this time (Table 2). The smaller size may make the tubers unharvestable. For greater tuber production it is more advantageous to harvest the tops after a hard frost. Protein levels in the forage will be reduced, but will still provide an acceptable feed. Roots, tubers and tops can be fed as a combined ration. Tops can be fed fresh or ensiled, although the forage does not ensile well because of its high concentration of soluble sugars and high moisture content. The potential advantage of the crop for forage may arise from the fact that it adapts well to a wide variety of soils and habitats.

Table 1. Feeding value and forage quality characteristics of Jerusalem artichoke tops and tubers and other selected forages.

Forage DM1 TDN DP CP CF % Jerusalem artichoke tops 27 67 3 5 18 Jerusalem artichoke tubers 21 78 6 10 4 Alfalfa, full bloom 91 53 10 14 35 Smooth brome, post bloom 94 46 2 6 33 Corn silage 29 70 5 8 22 Beet pulp 91 75 5 10 21

Morrison. Feeds & Feeding p. 1018 22 ed.

IDM - Dry matter, TDN - Total digestible nutrients, DP - Digestible protein, CP - Crude protein, CF - Crude fiber.

Table 2. The effect of top harvest on top and tuber yield of Jerusalem artichokes in 8-row, 30-foot plots on peat soil at North Branch, MN - 1981.

Cutting Scheme* Top Fresh Wt

(lb/acre) Tuber Fresh Wt

(lb/acre) Fresh Wt/Tuber

(%) Total Dry Wt

(lb/acre) 1 25637 1429 30.5 3298 2 23961 1457 - 3533 3 40584 1407 14.0 5689 4 5772 10654 57.5 7591 LSD 2990 874 31 474

*1 - Top harvest in early August

2 - Top harvests in early August and early September

3 - Top harvest in early September

4 - No top harvest prior to maturity

Source: Waters, et. al., University of Minnesota

III. Growth Habits:

The Jerusalem artichoke is a perennial with tuber bearing rhizomes. Stems are stout, pubescent and grow 3 to 12 ft in height. The leaves range from 114 to 3 in. wide and 4 to 8 in. in length. The plant bears many yellow flower heads in late August and September that are approximately 11/2 to 3 in. in diameter. The thick, rough textured leaves have coarse hairs on the upper surface and fine pubescence underneath. They are opposite on the lower part of the plant and alternate on the upper portion.

The tubers vary from knobby to round clusters, range from red to white in color, and are rougher in conformation than potato tubers. Cultivated varieties yield white tubers that are clustered near the main stem in contrast to wild types which produce reddish elongated tubers at the end of long rhizomes.

IV. Environment Requirements:

A. Climatic:

Most cultivars require a growing season of at least 125 frost-free days. Optimum yields are obtained where temperatures range from 65 to 80°F. Rainfall of 50 in. or less is required. In dry areas irrigation may be necessary to begin germination.

B. Soil:

Although the plant adapts well to a wide range of soil types and pH levels, artichoke production is favored by slightly alkaline soils. Yields are poor on heavy clays, particularly if there is waterlogging. Tuber and top yields are limited if soil moisture is less than 30% of field capacity during the tuber formation period (early September to November).

C. Seed Preparation and Germination:

Tubers sprout approximately 10 to 17 days after planting, but soil temperatures must be at least 44°F before germination begins. Jerusalem artichokes are propagated vegetatively by the use of sound, disease-free small tubers or pieces of tubers weighing approximately 2 oz and having at least 2 to 3 buds each.

V. Cultural Practices:

A. Method and Rate of Seeding:

Recommended planting rates of 1,000 lb/acre of seedstock tubers yield between 10,000 to 14,000 plants/acre. The tubers and tuber pieces are cut to approximately I to 2 oz in size and planted 12 to 24 in. apart with 30 to 36 in. between rows.

Table 3 shows yields of two varieties at two plant populations in 3 row, 20 ft plots in Minnesota. Fresh weight yields were higher with 18 in. × 12 in. spacings (29,040 tubers/acre) than 36 in. × 24 in. spacings (7,260 tubers/acre). These studies were conducted using 2 oz tuber pieces. Further Minnesota studies have indicated no difference in yield between 1 and 2 oz tubers; however, 1 oz tubers may be more susceptible to dessication in dry soils.

Table 3. Tuber yield of two Jerusalem artichoke varieties in two plant populations on sand soil at the Staples Irrigation Center, Staples, MN - 1981.

Variety Spacing (in) Tuber Fresh Wt

(lb/acre) Dry Wt/Tuber

(g) Mammoth French White 36 × 24 9791 9.1 Mammoth French White 18 × 12 16011 5.6 Columbia 36 × 24 24442 10.5 Columbia 18 × 12 34503 6.0 LSD 6331 1.8

Source: Waters, et. al., University of Minnesota

Planting depths are similar to potatoes. Tubers should be covered by 2 to 4 in. of soil. Hilling is recommended to increase moisture retention and to concentrate the tubers for easier harvesting. Because it is difficult to remove all of the tubers during harvest, additional planting may not be necessary in the second year.

B. Fertilization:

University of Minnesota trials on irrigated, leached sand soil have found increases in tuber yield in response to nitrogen rates of 60 and 120 lb/acre (Table 4). Yield increases in response to potassium were observed at rates of 150 lb/acre, but only at high nitrogen rates. Fertility programs similar to that of potatoes are suggested as a starting point for artichokes.

Table 4. Response of Jerusalem artichokes to nitrogen (N) and potassium (K) fertilizer on leached, sand soil at the Staples Irrigation Center, Staples, MN - 1981.

Fertilizer Applied (lb/acre) Tuber Wt

(lb/acre) Dry Wt/Tuber

(g) N K 0 0 9082 7.8 0 150 8467 8.7 60 0 11243 9.6 60 150 11831 11.4 120 150 13129 11.4 LSD 1520 3.2

Source: Waters, et. al., University of Minnesota

C. Varieties:

Many varieties of Jerusalem artichoke exist worldwide. Popular varieties in the U.S. and yields in Minnesota in, small plot trials are listed in Table 5.

D. Weed Control:

Mechanical: Jerusalem artichoke plants are extremely vigorous and will compete strongly with weeds. An early season cultivation is recommended to reduce emerging weeds, with a subsequent tillage operation to improve hilling of rows. Chemical: There are no herbicides currently registered for use in Jerusalem artichoke. Control of Jerusalem Artichokes in Subsequent Crops: Tubers over-winter very well in the soil. As a result, volunteer Jerusalem artichokes can be a serious weed problem in the following crop. It spreads into other crops, and will grow even taller than corn. One possible herbicide treatment to eliminate Jerusalem artichoke is Roundup (glyphosate). [Glyphosate should be applied in the fall to plants which were undisturbed all season]. Some Jerusalem artichokes will probably still escape and require treatment in subsequent years. 2,4-D and Banvel are effective herbicides for control of Jerusalem artichoke.

E. Disease and Their Control:

Few diseases are reported to affect Jerusalem artichoke. The primary disease is Sclerotinia (white mold), which can cause early wilt, stalk rot and degradation of the tubers. This pathogen also can cause severe yield reductions in dry edible bean, sunflower, and soybean.

If possible, susceptible crops should be rotated with small grains or corn. Avoid close rotations with dry edible beans, sunflowers, safflower, mustard and soybeans. Diseases such as downy mildew, rust and southern stem blight have been reported but have not been of economic concern. No fungicides are currently labeled for Jerusalem artichokes.

F. Insects and Their Control:

Insects have not been serious problems, but the potential is greater if large acreages develop. Stalk boring insects have been observed, but have caused limited damage. No insecticides are currently registered for use on the crop.

G. Harvesting:

Harvesting the tuber crop is similar to potatoes, with a few exceptions. The potato vine is weak and usually has senesced before harvest, which is in contrast to the continued growth of the strong artichoke stems. Potato tubers separate easily from the stems, while the large mass of artichoke tubers are strongly attached and intertwined with the roots. By adding small chains and increasing agitation, you can convert a potato digger to a Jerusalem artichoke digger. Artichoke tubers are smaller than potatoes, so these modifications are necessary to decrease the potential 50% loss that may occur with a conventional potato digger. Tops, roots, and tubers can be sorted as they are harvested, or they can be dried and then sorted. Artichoke tubers will wilt and soften much faster than potato tubers and thus cannot be left at low humidities too long before storage.

H. Storage:

Tubers can be harvested in the fall or left in the ground for winter storage and spring harvest. Tubers should be stored at 33 to 340 F and at very high humidity. Spoilage is more prevalent with diseased, bruised, or skinned tubers. Tubers that are kept for seed should not be frozen in storage.

VI. Yield Potential and Performance Results:

Typical tuber yields are approximately 15 ton/acre, with a range of 5 to 25 ton/acre. The variety and time of harvest determine the yields for both the tops and tubers. Total per plant yield ranges between 4 to 8 lb for tops, 3 to 6 lb for tubers, and 1 to 2 lb for roots.

Table 5. Tuber yield of four Jerusalem artichoke varieties in 3-row, 20-foot plots at Staples, MN - 1981.

Variety Tuber Fresh Wt

(lbs/acre) Tuber Dry Wt

(lbs/acre) Dry Wt/Tuber

(g) Columbia 22398 5769 15.7 Mammoth (MN) 8628 2166 9.3 Oregon 12477 3096 11.4 Mammoth 11159 2784 9.7 LSD 2612 552 5.2

Source: Waters, et. al., University of Minnesota

VII. Economics of Production and Markets:

A. Economic Factors:

Economic considerations for artichoke production will depend on numerous factors, including equipment and labor costs. Differences in variable and fixed costs make it difficult to estimate production expenses, but costs may range from $ 1,000/acre for seed, $60 to 150/acre for custom cutting and planting, $25 to 50/acre for custom cultivation, and $250 to 400/acre for custom harvesting. Additional expenses can include storage, transportation, and supplemental seedstock.

B. Market Potential:

The seedstock market for Jerusalem artichoke tubers is speculative and should not be relied on as an outlet. Between 1980 and 1982, the largest market was for seed tubers, which required a constant expanding production. Currently, the only stable market is a limited one for the tubers as a gourmet vegetable.

Market viability depends on the development of processing technology and the economic feasibility of such facilities. Consumer demand and a stable price for tubers are additional factors that contribute to its acceptability. Try to locate a guaranteed market and price before growing the crop.

VIII. Information Sources: