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Most farmers in Ontario consider Jerusalem artichoke, Helianthus tuberosus, to be a nuisance even though it is sold as a specialty vegetable. The popularity of the plant as a food source for both humans and animals has fluctuated throughout the years. The early settlers in North America, as well as the Indians, appreciated it as a readily available source of food, and their gardens became an important factor in the spread of the plant. In the past, it has been recommended as a forage plant, a feed for hogs, and as a leafy vegetable; at present it is also a potential source for sugar and alcohol production. It has not however, been cultivated widely in North America.
The name Jerusalem artichoke is somewhat misleading. The plant is not an artichoke and did not come from Jerusalem. Many consider the name to be a corruption of the Italian "Griasole Articiocco," meaning sunflower artichoke. The plant is a member of the sunflower family and is native to North America. It grows wild along river and stream banks, and in most meadows and valleys throughout Ontario. It has been cultivated as an ornamental and for its edible tubers, and has escaped to cultivated fields, fence lines, and roadsides.
Jerusalem artichoke (Figure 1) is a perennial plant that reproduces by seed and by fleshy rhizomes (underground stems) which bear small, potato-like tubers. The stems are stout, 1 to 3 metres in height, and become woody with age. The leaves are simple, rough-hairy, oval to lance shaped, with coarsely toothed edges. The flower heads are bright yellow and resemble those of the cultivated sunflower, but are smaller and produced at the ends of stems and axillary branches. The seeds are mottled black, flattened, wedge-shaped and smooth. Very few flowers develop seeds. The plants only produce seeds when pollinated by a different strain growing nearby. The rhizomes (Figure 2) produce tubers (Figure 3) which vary in size and shape from small, round and knobby to long, slender and smooth. The tubers may also vary in colour from white to pink or red. The cultivated strains of Jerusalem artichoke produce large tubers and shorter, thicker stems than the wild types.
Rhizomes and tubers act as nutrient reservoirs and represent a major means of regeneration. Shoots can arise from: (1) rhizomes; (2) tubers; and (3) pieces of rhizomes and tubers fragmented and dispersed during tillage of the soil.
Figure 1. Maturing Jerusalem artichokes in bloom.
Figure 2. Rhizomes of Jerusalem artichoke.
Figure 3. Tubers of Jerusalem artichoke.
Tubers are currently marketed in Ontario as a health food product. They contain inulin, a polysaccharide recommended at one time as a sugar easily digested by diabetics.
The excessive top growth or foliage of Jerusalem artichoke could be useful as a low-grade silage; however, unpalatability of the woody type stems may limit this use. Protein yields and the quality of the tuber pulp indicate some potential for it as a protein supplement in livestock feeds. The pulp is equal to or better than sugar beet pulp for this purpose.
The high levels of fructose found in Jerusalem artichoke make it an appealing possible alternative for sucrose, especially since the fructose is easily extracted from the tubers. Increases in the world prices for sucrose encourages the use of alternate sugars and since fructose is 1.5 times as sweet as sucrose it results in a lower calories to sweetness ratio. The first to use fructose was the soft drink industry and it is also being recommended for jams, jellies and preserves in the United States.
Considerable interest has been expressed in converting the fructose in the tubers to ethyl alcohol. Preliminary research at Morden, Manitoba suggested that it was possible to extract more ethyl alcohol per unit volume of Jerusalem artichoke than can currently be extracted from sugar beets. This potential will depend upon the status of traditional fuel resources.
Jerusalem artichoke is developing into a serious weed problem for Ontario farmers. Elimination of the plant is difficult because of the extensive underground rhizomes and tuber production. These spread throughout the field producing new plants which readily compete with the cultivated crop for light, nutrients and water. Studies have shown that high densities of Jerusalem artichoke can reduce corn seed yields by 25% and soybean seed yields by as much as 91%.
Viable tubers formed during the preceding year will produce shoots during the current growing season. Tillage in late June, after tubers have exhausted their food supply but before new tubers begin for form, will retard the spread of an infestation. Usually two to three tillage operations will be required to significantly reduce a well established population.
Frequent mowing of the top growth over a two to three-year period will drastically reduce heavy infestation. The first mowing of each year should be in May before the rhizomes start to form.
Cereal crops compete effectively with Jerusalem artichoke. In addition, they are usually harvested early enough to weaken the plants and reduce tuber and rhizome formation.
Herbicides used alone or with cultural practices have been successful in controlling Jerusalem artichoke. In a non-crop situation, Kilmor® at 1.0 L/ha or Banvel® at 0.7 L/ha has given 95 to 100% control when applied to Jerusalem artichoke as a split application. The first spray may be applied any time after the artichoke has reached 20 to 30 cm in height followed by the second application ten days later. A single application has given 50 to 80% control.
In field corn the same treatments may be applied; however, the second application may not be possible since corn will be brittle for 10 to 14 days following these treatments and travel within the field should be avoided. In addition, corn may be too tall for regular field equipment, but spot treating with a knapsack or backpack sprayer may be possible. Do not spray later than two weeks before silking or tasselling.
In a cereal crop the first application of Kilmor® or Banvel® should be made as recommended for annual broadleaf weed control followed by midsummer grain harvesting and then a second treatment after the artichoke has begun to regrow.
Roundup has been used for nonselective control of Jerusalem artichoke. This treatment is effective if applied at 6.5 to 9.0 L/ha in midsummer or late fall. It may be applied to regrowth following a cereal crop or in a non crop situation. Research has shown that an application in the spring to Jerusalem artichoke will give poor control.
Additional information on crop safety and precautions when using these chemicals is available in the Ontario Ministry of Agriculture, Food and Rural Affairs Publication 75, Guide to Weed Control. A combination of cultural and chemical control is the best method of stopping the spread of Jerusalem artichoke.
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