Equisetum arvense
(field horsetail)

E. arvense is circumpolar in distribution, throughout Europe and Asia, south to Turkey, Iran, the Himalayas, and across China (except the southeastern part), Korea and Japan. It is also found throughout Canada and the USA as far south as Georgia, Alabama, Arkansas, Texas, Arizona, New Mexico and California (Hultén and Fries, 1986). Holm et al. (1991) classifies E. arvense as a principal weed in Belgium, Canada, England, Finland, Germany, Japan, New Zealand, the former Soviet Union, the USA, the former Yugoslavia and as a common weed in Alaska, Argentina, Brazil, the former Czechoslovakia, France, India, Iran, Madagascar, Mauritius, Netherlands, Poland, Romania, Spain and Sweden. In Chile, China, Iceland, Italy, Korea and Turkey it is only reported as present.

E. arvense grows under a variety of soil and climatic conditions, but mainly in unproductive habitats such as marshes, swamps, ditches, river banks, open fields, open woods and areas such as road sides and railway embankments (Holm et al., 1977; Cody and Wagner, 1981). E. arvense is more common on sandy soils than on clay (Buchli, 1936). It grows in almost any substrate but prefers neutral or slightly basic soils (Meusel et al., 1971).

E. arvense is found in many arable crops (Håkansson, 1995c) as well as in open grassland, particularly in the temperate regions of the northern hemisphere. According to Holm et al. (1977) it is found in over 25 crops including beets, potatoes, and spring-sown and autumn-sown cereals. E. arvense is seldom ranked as a principal weed (Holm et al., 1977). In many parts of Europe, it is commonly found in orchards and other perennial crops (Håkansson, 1995b). It is also commonly found in first-year leys for cutting but, at least under Swedish conditions, is less commonly found in older leys for cutting (Håkansson, 1995a).

Large subterranean buds develop during the summer from an extensive rhizome system. They emerge as achlorophyllous spore-producing stems (10-20 cm) the following spring. Coning takes place mainly in April and May at about 60°N in Sweden and in July further north. The vegetative shoots (20-30 cm) appear about 1 week after the fertile stems, growing from smaller terminal or lateral rhizomatous buds, which were also formed the previous season. The terminal buds are always larger than the lateral buds and produce the first and also the most vigorous vegetative shoots in height and diameter.

E. arvense reproduces by spores on the fertile stem, but primarily by extensive rhizomes. Williams (1979) reported that about 50% of the rhizomes occupied the upper 25 cm of the soil profile, 25% occur in the next 25 cm of soil and the remaining 25% in the next 25 cm of soil. Under some circumstances, E. arvense reproduce by tubers that grow out from the nodes of the rhizomes and which, detached from the rhizome, may serve as a vegetative propagule.

E. arvense is slow-growing (Andersson and Lundegårdh, 1998a). Rhizomes planted in March attain their maximum shoot growth in July, their maximum shoot height in August, their maximum shoot number in September and accumulate dry matter in the rhizomes until October. The tubers are initiated in late summer and grow in size and number until November (Kvist and Håkansson, 1985; Marshall, 1986).

E. arvense is adapted to sunny habitats. It is dependent on its rhizomes and tubers for growth under heavy shade. For maximum growth, E. arvense has a high potassium demand, especially at high nitrogen levels (Andersson and Lundegårdh, 1998b). The shade sensitivity of E. arvense can partly be explained by its small, scale-like, non-functional leaves at the nodes (Holm et al., 1977). The assimilating capacity of the stem of E. arvense is not known (Borg, 1971). E. arvense seems to be sensitive to direct light competition. However, unfavorable conditions that do not decrease light may favour it. E. arvense is tolerant of low levels of nitrogen but will be overtopped by fast-growing species when competing for increased supplies of nitrogen. An increase in nitrogen supply and reduction in light, both increase the reduction of rhizome dry weight, whereas tuber production can be favoured by low nitrogen supply and high light intensities (Andersson and Lundegårdh, 1998a).

E. arvense can tolerate extended periods without rain because its rhizomes can extend several metres down into the soil (Cloutier and Watson, 1985; Reuss and Bachthaler, 1988) to escape the effects of tillage and herbicides (Williams, 1979). The tubers on the rhizomes act as organs of storage and regeneration, but the tubers may also disseminate the weed (Holm et al., 1977). Tuber size increases with depth (Williams, 1979), contributing to the plant's strong regenerative capacity. It has been reported to emerge through silt layers up to 1 m thick following flooding (Holm et al., 1977).

Species pathogenic on E. arvense include Fusarium semitectum (in Alaska, USA), Leptosphaerie hiemalis (in Canada), Mycosphaerella tassiana (in Greenland), Phoma equiseti (in Nova Scotia, Canada) and Gloeosporium equiseti (in Ontario, Canada) (Cody and Wagner, 1981)

Herbivores that feed on E. arvense include ducks (Hauke, 1966), the homopteran Macrosteles borealis and the hymenopteran Dolerus spp.; the coleopterans Grypidus equiseti, Grypus spp. and Hippuriphila spp. are found associated with E. arvense (Cody and Wagner, 1981).

Materials

• Gum/resin
• Poisonous to mammals

Medicinal, pharmaceutical

• Traditional/folklore

E. palustre is distinguished from E. arvense because it has no tubers on the rhizomes, its sterile and fertile spore-bearing stems are similar in appearance and emerge at the same time and its spore-bearing cones usually appear at the tips of the stems but sometimes appear at the tips of the branches (Holm et al., 1977). The sterile stems of E. palustre might also be mistaken for those of E. arvense, however, the first branch internodes of E. palustre are shorter than the subtending stem sheath rather than longer as in E. arvense (Cody and Wagner, 1981).

Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.

Introduction

E. arvense has a prolonged storage phase in rhizomes and tubers, which lie deep in the soil, this gives it the potential to be a persistent and troublesome weed (Marshall, 1986; Andersson and Milberg, 1996; Andersson, 1997).

Cultural Control

A 50-year study of E. arvense showed that annual cultivation, combined with the use of herbicides to control annual broad-leaved weeds, resulted in E. arvense becoming a dominant weed species. This implies it is highly sensitive to competition, with light as a main factor (Karch and Speri, 1979). A large study, conducted in Finland, shows that the abundance of E. arvense decreased significantly in spring cereals from the 1960s to the 1980s, probably due to improved cultivation techniques and new competitive crop varieties (Erviö and Salonen, 1987). Data from a long-term experiment have shown that E. arvense can become a dominant weed species in low-yielding crops receiving little or no nitrogen fertilizer (Andersson and Milberg, 1996). Williams (1979) showed that E. arvense has a weak response to nitrogen at levels corresponding to those given to agricultural crops. That E. arvense is sensitive to crop competition has also been shown by Cloutier and Watson (1985). Cultivation depletes the extensive underground food reserves of E. arvense. However, E. arvense is very persistent because of its extensive underground root and rhizome system. Soil compaction and prolonged cereal rotations (Bachthaler, 1985) increase the abundance of E. arvense. Repeated hoeing during one season has little effect on E. arvense (Cloutier and Watson, 1985) but minimum tillage in monocultures seems, after some years, to favour E. arvense (Légère, 1993).

The increased frequency of E. arvense in nitrogen-free fertilized plots in fields with increased amounts of potassium shows that potassium availability may restrict the growth of E. arvense even in soil unfertilized by nitrogen (Andersson, 1997). Consequently, nitrogen fertilization of crops under field conditions will not favour the growth of E. arvense, instead, it will be suppressed by increased light interception by the crop (Andersson and Milberg, 1996).

Chemical Control

There is no effective chemical control for E. arvense. The use of selective foliage-applied herbicides (Marshall, 1984) has no pronounced long-term effect on E. arvense growing in crops because of its deep-rooted system of rhizomes and tuberous storage organs and an extended period of emerging vegetative shoots (Korsmo, 1954; Kvist and Håkansson, 1985; Marshall, 1986). Glyphosate, MCPA, dichlorprop and mecoprop have only a limited effect on the growth of E. arvense the year after application (Hallgren, 1996). There is large variation in the physiological activity of E. arvense which may partly be responsible for the lack of effectiveness of herbicides. However, July-October is significant for rhizome growth, tuber initiation and the sustained storage of assimilates in the underground system (Marshall, 1986). August applications of glyphosate gave consistently better control compared with those earlier in the season, presumably because the increased movement of assimilates during the late summer to the regions of active growth (rhizome apices, nodes, and tubers) is also conducive to translocation (Marshall, 1980).