Arracacia xanthorrhiza
(arracacha)

A. xanthorriza is a biennial to perennial herb, which is mainly reported from cultivation or as persistent in old fields and nearby areas. It is mostly confined to South American Andean regions and is a major commercial crop in Brazil. It is used by an estimated 30 million people in the Andes and 30 million people elsewhere, mainly in Brazil (Heywood, 2014). It is not considered as an invasive species and wild populations are scarce (Hermann, 1997).

Outside of South America, it is reported as commercially cultivated in Puerto Rico and Costa Rica (Hodge, 1954). It is not reported as an invasive species in any of the places where is cultivated. It is listed as a species that has naturalised in Cuba with the tendency to spread in some localities (Oviedo Prieto et al., 2012). Its introduction has been unsuccessful in some countries due to its photoperiod and temperature requirements, long growing cycle, its susceptibility to pests and diseases and the short shelf life of the roots (FAO, 2016).

A. xanthorrhiza is a biannual to perennial herb native to the Andes in South America, and has been cultivated for thousands of years (Heywood, 2014). Wild populations are rare (Hermann, 1997). It is mostly cultivated on a large scale in Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile, and Brazil (Hermann, 1997). It is also cultivated, but on a smaller scale, in Central America and the Caribbean (Heiser, 1965; Kay, 1987; Hermann, 1997). It is also reported from a few countries in Asia, Indonesia, Africa, North America, Europe and Oceania. The species is no longer present in some of the countries where it was introduced, and there is some uncertainty about its current presence in others (Hodge, 1954).

A. xanthorrhiza is a species with a low risk of introduction. It is mainly known from cultivation, with some wild populations known from the Andean highlands (Hermann, 1997). It is only listed as a species that might become invasive in Cuba, without further details (Oviedo Prieto et al., 2012). The species rarely reproduces by seeds, being vegetatively reproduced through its cormels (Hermann, 1997). It has been tried as a crop in various countries in the past without success, mainly due to its specific environmental requirements and its susceptibility to pests and diseases in warmer tropical areas. It does not develop storage roots under warm tropical conditions or in temperate zones, so the introduction to those areas is unlikely (Hermann, 1997; Hanelt and IPK, 2016).

A. xanthorrhiza natural habitat is not well known since the species is principally known from cultivation in tropical highlands (Hermann, 1997). The species is believed to have its origins in the Andean tropical highlands, in “cloudy areas with a constant humidity” (FAO, 2016). The reported wild populations occur along roadsides, disturbed sites or in “borders of natural vegetation” (Hermann, 1997).

Development and Reproductive Biology
The central rootstock is a swollen and compressed structure, and bears conical to cylindrical storage roots that each weigh 100 to 330 g. The rootstock also bears aerial stems or offshoots known as cormels which are segmented structures derived from stem tissue and have internodes, nodes and scars left from shed leaves. These may be used to propagate new plants. These offshoots bear 3–5 petiolate leaves and each will develop an inflorescence, a terminal umbel. Normally under cultivation flowering is rare but if allowed to flower the flowering period is 1–2 months long (Hermann, 1997).

The species seems to be a facultative outbreeder. Seeds are orthodox with a germination not higher than 30% (Hermann, 1997). Seeds are seldom formed, as plants are usually harvested before the flowers are produced (Hodge, 1954; Kay, 1987). Seed set is impaired by high temperatures and anthers shrivel before they can shed pollen at those temperatures (Hodge, 1954).

Physiology and Phenology
A. xanthorrhiza has slow growth and will take 10–16 months for the roots to be ready for harvesting (Hermann, 1997). Short days and a moderate and evenly distributed rainfall of at least 600 mm are preferred for the storage roots to develop well (Kay, 1987). The application of phosphorus has been found to increase yields considerably, while heavy applications of nitrogen have an adverse effect (Heywood, 2014).

The cultivated plants rarely flower due to the plants being harvested before flowering and because of the specific environmental conditions required. A combination of low temperatures, short days and drought periods are apparently needed to induce flowering. Flowering duration is 1–2 months (Hermann, 1997).

Environmental Requirements
The species grows best in the tropical highlands, from 900 to 3300 m elevation, with an annual rainfall ranging from 600 to 5000 mm and mean temperatures of 15–20°C. It is not tolerant of frosts. The species will not develop the storage roots and will be affected by pests and diseases at higher frequencies in hot and wet environments. Plants thrive best when soil moisture is available throughout the cultivation period (Hodge, 1954; Hermann, 1997). Shading reduces the production of the storage roots (Barrella et al., 2011). It grows in well-drained medium (loamy) soils with acid, neutral or alkaline pH (PFAF, 2016).

Many pests and diseases affect A. xanthorrhiza but they are usually controlled by crop rotations and management practices (Henz, 2002). Some of the organisms reported affecting the species are: the bacteria Pectobacterium spp., Erwinia spp. and Xanthomonas campestris; the insects Tetranychus spp., Agrotis ipsilon, Conotrachelus cristatus, Epitrix spp., Systena sp., Papilio polyxenes, Automeris spp., Erythrogonia quadriguttata, Amastris simillima, Ellipes minuta, Ancognatha scarabeoides, Tetranychus spp. and several genera of the subfamily Melolonthinae of the Scarabaeidae; the fungi Sclerotinia sclerotiorum, Athelia rolfsii, Fusarium spp., Phoma sp., Rhizopus sp., Cercospora spp., Passalora depressa, Septoria apiicola, Gloeosporium sp., Ceratocystis fimbriata and Rhizoctonia sp.; the nematodes Meloidogyne sp. and Pratylenchus penetrans; and the oomycete Phytophthora palmivora (Lenys et al., 1984, Romeiro et al., 1988, Fornazier 1996, Rosa-Márquez et al., 2000, Henz et al., 2005, FAO, 2016, Melo et al., 2016).

Some viruses have been described for the species, their effects still not fully known: AVA (arracacha virus A), AVB (arracacha virus B), the potyvirus AP-1, the carlavirus AV-3 and PBRV/A (Kay, 1987; Orílio et al., 2009). Bidens mosaic virus was first reported on an arracacha crop in Brazil by Orílio et al. (2017).

Animal feed, fodder, forage

• Fodder/animal feed

Human food and beverage

• Beverage base
• Flour/starch
• Food additive
• Root crop
• Vegetable

Medicinal, pharmaceutical

• Traditional/folklore
• Veterinary

The South American Arracacia species are not well defined, as some of the descriptions are poor due to lack of good herbarium specimens (Hermann, 1997). Molecular and morphological studies show that A. xanthorrhiza and A. equatorialis are closely related (Blas et al., 2008). These species are differentiated by the incisions of leaflets, and the shape and margin of involucel. The taxonomic differentiation among the wild Andean species is even more complicated as hybridization between the cultivated varieties and the wild populations occurs. A. incisa and A. xanthorrhiza are also morphologically similar (Hermann, 1997). A. xanthorrhiza is widely distributed through Bolivia, Peru and Ecuador at elevations of 2000-4000 m; A. incisa is confined to the highlands of the central and southern regions of Peru.

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.

The herbicides halosulfuron, flazasulfuron, imazamox and bentazon have been reported to cause high toxicity and damage to A. xanthorrhiza when grown as a crop. Low and medium doses of linuron and oxadiazon, and low doses of ammonium-glufosinate, can be toxic in the early stages, but plants eventually recover (Freitas et al., 2004).

Hermann (1997) reports the following research needs: the systematic relationships of the species to its closely related wild relatives; studies of the factors inducing flowering, research on the breeding system, seed conservation; how can the crop duration be reduced; and the improvement of the storage life of the root.

In terms of invasiveness, more information is needed to assess whether the species is invasive and has any effects on other species or habitats outside its cultivation.

01/12/2016 Original text by:

Jeanine Vélez-Gavilán, University of Puerto Rico at Mayagüez