Ditylenchus destructor (potato tuber nematode)
- Taxonomic Tree
- Notes on Taxonomy and Nomenclature
- Distribution Table
- Risk of Introduction
- Hosts/Species Affected
- Host Plants and Other Plants Affected
- Growth Stages
- List of Symptoms/Signs
- Biology and Ecology
- Natural enemies
- Notes on Natural Enemies
- Seedborne Aspects
- Pathway Vectors
- Plant Trade
- Detection and Inspection
- Similarities to Other Species/Conditions
- Prevention and Control
- Distribution Maps
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PicturesTop of page
IdentityTop of page
Preferred Scientific Name
- Ditylenchus destructor Thorne, 1945
Preferred Common Name
- potato tuber nematode
International Common Names
- English: eelworm, potato; eelworm, potato tuber; potato eelworm; potato rot nematode
- Spanish: anguilulosis de la patata; nematodo de la patata; nematodo de la pudricion de la papa (Mexico)
- French: maladie vermiculaire des pommes de terre
Local Common Names
- Denmark: kartoffelradnematod
- Finland: lahoankeroinen
- Germany: Aelchen, Kartoffelkraetze-; Aelchen, Kraetze-; Aelchen-Kraetze der Kartoffel (Folgeerscheinung); Nematodenfaeule der Kartoffel (Folgeerscheinung)
- Italy: Anguillulosi delle patate
- Netherlands: Destructoraaltje
- Norway: potetratenematode
- Sweden: potatisrötnematod
- DITYDE (Ditylenchus destructor)
Taxonomic TreeTop of page
- Domain: Eukaryota
- Kingdom: Metazoa
- Phylum: Nematoda
- Class: Secernentea
- Order: Tylenchida
- Family: Anguinidae
- Genus: Ditylenchus
- Species: Ditylenchus destructor
Notes on Taxonomy and NomenclatureTop of page
DescriptionTop of page
Measurements (after Thorne, 1945).
Females: length=0.81-1.4 mm; a=30-35 µm; b=8-10 µm; c=15-20 µm; V=78-83%.
Males: length=0.8-1.3 mm; a=34-40 µm; b=7-8 µm; c=12-16 µm; T=73-80%.
There is considerable morphological variation shown by the adults of this species due to age or feeding on particular hosts. Body slender (a=30-35 µm). Cuticle smooth, marked by faint and fine transverse striae about 1 µm apart; lateral field with six incisures. Cephalic region smooth, low, anteriorly flattened, slightly set off or almost continuous with body contour. Cephalic framework hexa-radiate, moderately developed. Stylet slender, 10-14 µm long, with distinct basal knobs. Median oesophageal bulb fusiform; basal bulb clavate, usually its base overlaps the intestine on the dorsal side for half to one body width. Excretory pore at or just anterior to oesophago-intestinal junction; hemizonid just in front of excretory pore. Tail conoid, slightly arcuate ventrally, with a minutely rounded tip.
Female: vulva a transverse slit, at 78-83% of body length from anterior end. Ovary single, outstretched anteriorly, sometimes reaching the oesophagus; oocytes in double rows in anterior region, then in single file. Spermatheca elongate-oval, often with large sperm arranged in a row. Post-vulval uterine sac about 75% of vulva-anus distance. Tail 3-5 anal body widths long, with a minutely rounded tip.
Male: abundant, similar to female in general appearance. Testis single, outstretched; sperm large-sized, rounded, in 1-2 rows. Spicules large and prominent, ventrally arcuate. Gubernaculum linear. Bursa enveloping about four-fifths of tail.
Juveniles: four juvenile stages, resembling female in general morphology but lacking genital structures; first stage occurring within the egg which is oval, about twice as long as wide.
Anderson and Darling (1964) have given detailed information on reproduction and embryology.
DistributionTop of page
D. destructor is a pest of potatoes mainly in temperate regions: localised areas in North America and many parts of Europe, the mediterranean region and Asia. Pre-1995 records from groundnut and several weeds in South Africa are now considered to be of D. africanus although D. destructor has been validly reported from this country (EPPO, 2014).
Records of D. destructor in New South Wales, South Australia, Victoria and Western Australia (CABI/EPPO, 2001; EPPO, 1996) published in previous versions of the Compendium are erroneous. Recent surveys in New South Wales, Queensland, South Australia, Victoria and Western Australia (e.g., Riley and Kelly, 2002; Walker, 2004; Hay and Pethybridge, 2005; Hall et al., 2007) failed to find any specimens of D. destructor and previous reports in these states were based on erroneous information (Hodda and Nobbs, 2008). D. destructor has been detected in Tasmania in 1961 by Thistlethwayte. This single reference is the last and only known report of the presence of D. destructor in Tasmania.
Records of D. destructor in Guizhou and Yunnan, China (Sun et al., 1994) published in previous versions of the Compendium were included in error and have been removed. Zhao et al. (2010) has since reported D. destructor causing soft rot of Angelica sinensis in Yunnan.
Records of D. destructor in North Carolina and Virginia (CABI/EPPO, 2009; EPPO, 2009) published in previous versions of the Compendium are now known to be based on erroneous information. There are no published reports of D. destructor in North Carolina and Virginia, and the species has never been detected in these states (North Carolina Department of Agriculture and Consumer Services, personal communication, 2010; Virginia Department of Agriculture and Consumer Services, personal communication, 2011).
A record of D. destructor in Peru (Jatala et al., 1977) published in previous versions of the Compendium is considered invalid. D. destructor has not been detected or reported in Peru (SENASA, 2012, personal communication).
Distribution TableTop of page
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.Last updated: 25 Feb 2021
|Continent/Country/Region||Distribution||Last Reported||Origin||First Reported||Invasive||Reference||Notes|
|South Africa||Present, Localized|
|Bangladesh||Absent, Unconfirmed presence record(s)|
|-Inner Mongolia||Present, Few occurrences|
|India||Absent, Unconfirmed presence record(s)|
|Malaysia||Absent, Unconfirmed presence record(s)|
|Turkey||Present, Localized||First reported: 197*|
|Bulgaria||Present, Localized||First reported: 196*|
|Czechia||Present, Few occurrences|
|Finland||Absent, Intercepted only|
|Ireland||Present, Few occurrences|
|Italy||Absent, Unconfirmed presence record(s)|
|Netherlands||Present, Localized||Present, in all parts of the area where host crops are grown.|
|Norway||Present, Few occurrences|
|Spain||Absent, Formerly present|
|-Canary Islands||Absent, Invalid presence record(s)|
|Sweden||Present, Few occurrences|
|Switzerland||Present, Few occurrences|
|United Kingdom||Present, Few occurrences|
|-England||Present, Few occurrences|
|-Scotland||Present, Few occurrences|
|Canada||Present, Few occurrences|
|-British Columbia||Absent, Invalid presence record(s)|
|-Ontario||Present, Few occurrences|
|-Prince Edward Island||Absent, Eradicated|
|Haiti||Absent, Unconfirmed presence record(s)|
|United States||Present, Localized|
|-Arkansas||Absent, Unconfirmed presence record(s)|
|-Indiana||Absent, Unconfirmed presence record(s)|
|-New Jersey||Absent, Unconfirmed presence record(s)||Original citation: USDA-APHIS, personal communication, 2009|
|-North Carolina||Absent, Invalid presence record(s)||Original citation: USDA-APHIS, personal communication, 2010|
|-Virginia||Absent, Invalid presence record(s)||Original citation: USDA-APHIS, personal communication, 2011|
|-West Virginia||Absent, Unconfirmed presence record(s)|
|Australia||Absent, Invalid presence record(s)|
|-New South Wales||Absent, Invalid presence record(s)|
|-South Australia||Absent, Invalid presence record(s)|
|-Tasmania||Absent, Invalid presence record(s)|
|-Victoria||Absent, Invalid presence record(s)|
|-Western Australia||Absent, Invalid presence record(s)|
|New Zealand||Present, Localized||1979|
|Ecuador||Absent, Formerly present||Original citation: AGROCALIDAD, 2012, personal communication|
|Peru||Absent, Invalid presence record(s)||Original citation: SENASA, 2012, personal communication|
Risk of IntroductionTop of page
Seed potatoes carry the infection and spread the disease, and hence must be subject to proper phytosanitary regulations
In Wisconsin, USA, the spread of the pest has been stopped through the elimination of infection sources by fumigation, a strict state quarantine limiting movement of infected tubers, and supervision of the disposition of potatoes from infested fields (Darling et al., 1983).
The requirement of the nematode for high relative humidity means it would be unlikely to become a problem in areas with warm, dry soils; it may therefore be of concern to potato production only in the cooler areas, including northern parts of the EPPO region. However, D. africanus (formerly identified as D. destructor), as a groundnut pathogen in South Africa, has adjusted to different (and normally unfavourable) climatic conditions (De Waele and Wilken, 1990; see data sheet on D. africanus).
Hosts/Species AffectedTop of page
In southern Sweden, D. destructor parasitizes potatoes and occurs on the weed species Elytrigia repens [Elymus repens], Artemisia vulgaris, Cirsium arvense, Potentilla anserina and Rumex acetosella, which are a source of infection to potatoes. Trifolium pratense, T. repens and T. hybridum are good hosts of D. destructor; Festuca pratensis and Medicago sativa are less good hosts (Andersson, 1971).
D. destructor was reported for the first time from Norway on potatoes and carrots (Stoeen, 1977), on potatoes in Peru (Jatala et al., 1977), on ponderosa pine in California, USA (Viglierchio, 1978) and on Cimicifuga racemosa (Planer, 1972). It occurs in Poland on potato, carrot, beetroot, onion and other crop plants, on ornamentals (hyacinth, crocus) and on several weeds. Outbreaks of disease caused by this nematode are sporadic, but the actual extent of its distribution in Poland is unknown.
It attacks strawberry in Moldavia (Smirnova and Koev, 1976; Efremenko and Burshtein, 1975); potato in Lithuania (Efremenko and Burshtein, 1972); flowering plants (Ladygina and Volodchenko, 1972) and potatoes (Kapitonenko, 1972) in Ukraine; hops (Humulus lupulus) in Bulgaria (Katalan-Gateva and Konstantinova-Milkova, 1975); potato, onion, lupin and other crops in Belorus (Ivanova, 1971a, b). In Russia, D. destructor was found on 11 of 13 species of weed commonly growing in potato fields in the Moscow region. Solanum nigrum, Taraxacum officinale (20%) and Barbarea vulgaris (16%) were the most heavily infected; Fumaria officinalis and Matricaria inodora [Matricaria perforata] also served as hosts for this nematode (Ivanova, 1973).
In Iran, Kheiri (1972) reported D. destructor to be associated with many crop plants, for example potato, wheat, bean, soyabean, aubergine, tomato, tea, maize, orange and alfalfa. It was found parasitizing sweet potato, potato and Mentha in China (Ding and Lin, 1982) and ginseng in Korea (Young and Seung, 1995). This nematode was recorded for the first time in New Zealand as causing damage to hops in South Island (Foot and Wood, 1982). In Japan 18 plant species, including Brassica chinensis, B. oleracea, Capsicum annuum, Chrysanthemum morifolium [Dendranthema morifolium], Cucumis sativus, Cucurbita moschata and Lycopersicon esculentum, are hosts for D. destructor (Nakanishi, 1979).
Host Plants and Other Plants AffectedTop of page
Growth StagesTop of page
SymptomsTop of page
There are, in general, no obvious symptoms in the aerial parts of the plant, although heavily infested tubers give rise to weak plants which usually die. Early infections can be detected by peeling the tuber, which can reveal small, off-white spots in the otherwise healthy flesh. These later enlarge, darken, are woolly in texture and may be slightly hollow at the centre. If stored in moist conditions a general rot may ensue and spread to other tubers. Infested dahlia tubers develop similar syptoms (Myuge, 1957; Hooper, 1973).
On badly affected tubers there are typically slightly sunken areas with cracked and wrinkled skin which is detached in places from the underlying flesh. The flesh has a dry and mealy appearance, varying in colour from greyish to dark brown or black. This discoloration is largely due to secondary invasion of fungi, bacteria and free-living nematodes (the latter are easily confused with D. destructor). In contrast, the skin of potatoes infested with D. dipsaci is not usually cracked, and the rot darkens towards the inside of the tuber. The symptoms are more obvious in the foliage, which is shortened and malformed. Rotting due to D. destructor in storage increased with rising temperature, but there was no evidence of transfer of infestation from diseased to healthy tubers (Andersson, 1971). It spread from infected to healthy potato plants when spaced at 70x20 cm or less in the sod-podzolic soil in the Ukraine (Polozhenets', 1977).
On Iris and tulips
Infestations usually begin at the base and extend up the fleshy scales, causing grey-to-black lesions; roots may be blackened, and leaves poorly developed with yellow tips.
The following symptoms were originally recorded for D. destructor on groundnut; however, the Ditylenchus attacking groundnut has now been shown to be a different species, named D. africanus (Wendt et al., 1995).
D. destructor was reported to occur in large numbers in the hulls and seeds of groundnut. At 85 days after planting, the nematodes were found 3-5 cell layers deep in the exocarp at the base of groundnut pods, near the point of connection with the peg. The nematodes rapidly invaded the developing pods after fruiting pegs had penetrated the soil; very few were found in roots. The surface of the infection site showed brown, spongy cork cells, and from this site the nematodes invaded the pegs. Hulls of groundnuts showed black discoloration which appeared first along the longitudinal veins. The kernels were shrunken. The infected testae were brown to black and the embryo showed a brown discoloration (Jones and De Waele, 1988). Feeding in the parenchyma of the peg caused the cells to collapse. Empty and collapsed cells were pushed aside, creating channels through which the nematodes moved. From the peg, the nematodes further penetrated the exocarp to feed on the parenchymatous cells surrounding the vascular bundles. They also migrated to the base of the mesocarp through the natural opening at the point of peg attachment (Jones and De Waele, 1990). In the testa, the nematode feeding on the tissues near or within the vascular bundles caused discoloration of vascular strands within the seed coat. It aggregated in large numbers near the vascular bundles in the exocarp; these tissues are thought to facilitate migration of the nematode. The nematode did not invade the cotyledons (Jones and De Waele, 1990).
Thorne (1961), Hooper (1973), MAFF (1974), Esser and Smart (1977), Dement'eva, (1980) and Ambrogioni et al. (1995) give general accounts of D. destructor, including its morphology, geographical distribution, symptoms, pathogenicity, transmission and control.
List of Symptoms/SignsTop of page
|Leaves / abnormal colours|
|Leaves / necrotic areas|
|Roots / soft rot of cortex|
|Vegetative organs / internal rotting or discoloration|
|Vegetative organs / surface cracking|
Biology and EcologyTop of page
D. destructor attacked carrots at the base of the lateral roots and tissue breakdown occurred in the cortex. The damaged tissue was discoloured. External lesions subsequently appeared which served as infection sites for other pathogens, including Mycocentrospora acerina (Stoeen, 1977). It was found to attack stems, buds and leaves of Cimicifuga racemosa (Planer, 1972) and roots of ginseng in Korea (Young and Seung, 1995). Stem infestations are rare but have also been reported on potato haulm by Goodey (1951) and on Vicia sativa by Duggan and Moore (1962).
Means of movement/dispersal and survival
The nematodes can move only short distances in the soil and have no natural means of long-range movement. The main means of dispersal is with infested potato tubers or other subterranean organs of host plants, for example bulbs and rhizomes (especially of iris). Transport in infested soil is another important means of spread. Irrigation water can also carry the nematodes. Unlike the closely related species D. dipsaci, D. destructor is unable to withstand excessive desiccation, and for this reason is usually important only in cool, moist soils. Unlike D. dipsaci, it does not form 'eelworm wool'. Without a resistant resting stage, the species overwinters in soil as adults or larvae and may even multiply by feeding on alternative weed hosts (for example Mentha arvensis, Sonchus arvensis) and on fungal mycelia. It may also possibly overwinter as eggs. These hatch in the spring and larvae are immediately able to parasitize hosts. Thorne (1961) suggested that D. destructor overwintered in USA field soil as eggs and coiled adults. In Ireland, its survival in soil is helped by the presence of corn mint and unharvested potato tubers (Anon., 1972).
Interactions with other organisms
Rhizoctonia solani infections of potato tubers (var. Janka and Leda) were highest in pots to which the largest number of D. destructor (136 nematodes per 100 g soil) was added. The results confirmed that mixed infections were more harmful to the potatoes than either infection alone (Janowicz and Mazurkiewicz, 1982).
The damage to potato tubers stored in the dark at 6-15°C was greater (49% compared to 27%) when both the dry rot fusaria (Fusarium solani var. coeruleum, F. culmorum and F. oxysporum) and D. destructor were present, than when only the dry rot fungi were present (Janowicz, 1984).
D. destructor can feed on fungi and hence can easily be cultured on many fungi and on plant callus (Darling et al., 1957; Faulkner and Darling, 1961). It is readily established on laboratory cultures of Alternaria tenuis [A. alternata] and A. solani (Foot and Wood, 1982). D. destructor reproduced well on cultures of A. tenuis on potato glucose agar at 26-27°C (Pupavkina, 1971). It was cultured on ginseng root callus, fungal mycelium (F. solani), carrot discs and radish sprouts (Young and Seung, 1995).
Natural enemiesTop of page
|Natural enemy||Type||Life stages||Specificity||References||Biological control in||Biological control on|
Notes on Natural EnemiesTop of page
In Germany, the bulb mite Rhizoglyphus echinopus was found to feed on D. destructor. It may be of importance in regulating nematode populations under certain conditions (Sturhan and Hampel, 1977).
Seedborne AspectsTop of page
Pathway VectorsTop of page
Plant TradeTop of page
|Plant parts liable to carry the pest in trade/transport||Pest stages||Borne internally||Borne externally||Visibility of pest or symptoms|
|Bulbs/Tubers/Corms/Rhizomes||adults; eggs; juveniles||Yes|
|Growing medium accompanying plants||adults; eggs; juveniles||Yes||Pest or symptoms not visible to the naked eye but usually visible under light microscope|
|Seedlings/Micropropagated plants||adults; eggs; juveniles||Yes|
|Stems (above ground)/Shoots/Trunks/Branches||adults; eggs; juveniles||Yes|
|Plant parts not known to carry the pest in trade/transport|
|Fruits (inc. pods)|
|True seeds (inc. grain)|
ImpactTop of page
D. destructor was commonly recorded on seed potatoes from the Ural region, Central Asia (Artem'ev, 1976). It is widespread on potatoes in the Central Chernozem zone of the RSFSR and causes considerable losses (Chukantseva, 1983). In Uzbekistan, D. destructor represented 84.7% of the total nematodes found on potato tubers (Adylova and Vasilevskii, 1983). It is also widespread on potatoes in Kazakhstan (German, 1972) and in Azerbaijan (Ismailov, 1976). Severe infestations of potatoes have been reported in the Samarkand, Tashkent and Fergana regions of Uzbekistan (Usmanova, 1972).
Effect on vertebrates
When animals were fed potato tubers infected with D. destructor or were injected with extracts from such tubers, the intensity of antibody production was reduced by half or more, and the phagocytic activity of leukocytes and the cholesterol content of the blood were also reduced (Savchuk and Savchuk, 1972).
Detection and InspectionTop of page
Prior to planting, soil can be sampled using a standard extraction procedure for nematodes of this size (Hooper, 1986). Microscopic examination of the nematode is necessary for correct identification of the species.
It is difficult to detect the presence of D. destructor on potatoes from external tuber appearance alone. Sample tubers should be cut or peeled to look for the characteristic whitish pockets in which most of the nematodes are found. However, on badly affected potato tubers there are typically slightly sunken areas with cracked and wrinkled skin which is detached in places from the underlying flesh (see Symptoms). The flesh has a dry and mealy appearance, varying in colour from greyish to dark brown or black. External symptoms on iris and tulip include grey-to-black lesions; heavily infested bulbs often have blackened roots and poorly developed, yellow-tipped leaves.
A diagnostic protocol for Ditylenchus destructor is described in EPPO (2008).
Similarities to Other Species/ConditionsTop of page
D. africanus [=D. destructor of earlier workers] can be confused with another endoparasite of groundnut pods and seeds, Aphelenchoides arachidis, which parasitizes the testa of groundnut (Bos, 1977) and is an important seedborne pest of groundnut (Bridge et al., 1977; Bridge and Hunt, 1985). The histopathology of both these parasites on groundnut is similar (Jones and De Waele, 1990).
Prevention and ControlTop of page
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.
Treatment of Potato Tubers
D. destructor was first found on potatoes in Wisconsin, USA in 1953. Spread of the pest has been stopped through the elimination of infection sources by fumigation and the application of strict state quarantine limiting movement of infected tubers (Darling et al., 1983).
Treatment with soil-applied nematicides can provide a high level of control but can be expensive. Granulated nematicides were reported to be effective against the nematode. Heterophos solutions caused a decrease in the levels of infestation of the new crop, stimulated growth and development of the plant and brought about yield increases of 10-40 centners [1000-4000 kg]/ha in the central Chernozem zone of the RSFSR (Chukantseva, 1983). Heterophos granules applied before planting of D. destructor-infested seed potatoes reduced infestation to 3.8 and 2.7% compared to 25% in untreated controls, and had a positive effect on the number of stems and their height (Vorona, 1984).
Fostil used for soaking potatoes before planting was effective against D. destructor in Russia. Carbathion [metam] was also effective, but phytotoxic (Chukantseva, 1976). Sorting out of 'clean' seed potatoes, or treatment with dimethoate and carbathion [metam], were both effective against D. destructor in Azerbaijan; metam somewhat decreased germination (Ismailov, 1976).
Dipping potato tubers in thionazin (superseded) controlled D. destructor and secured a yield of nematode-free tubers (Wilski, 1972). Ivanova and Bogdan (1983) in Belorussia considered the immersion of potato planting material into an aqueous solution of carbathion [metam] as an effective control method. Treatment of soil with metam reduced infestation from 27.5 to 4% (Adylova and Vasilevskii, 1983); however Chukantseva (1983) found that the treatment with carbathion [metam] was phytotoxic and could not be recommended in the central Chernozem zone of the RSFSR region.
Treatment of Bulbs
Diazinon decreased D. destructor populations by 37-48% (Rasinya and Rasina, 1972).
Infestations in iris bulbs can be controlled by immersion in hot water containing 0.5% formaldehyde, at 43.5°C for 3 h. The bulbs may be soaked for 2.5 h in a solution of thionazin (superseded) plus formaldehyde. Both methods cause some damage to bulbs. In iris (cv. Wedgewood) bulbs infested with D. destructor, effective control resulted from hot-water treatment for 3 h at 43.6°C after warm storage for 7 days at 30°C (ISEHS, 1974). Pre-treatment of iris bulbs for 3-4 weeks at 30°C gave protection against D. destructor (Bulb Research Centre, 1973). With adequate pre-warming of the bulbs, hot-water treatment to control D. destructor is safe and effective and preferable to the use of a toxic chemical. Iris bulbs may be stored at 30°C for 1-2 weeks and then soaked for 3 h in water at 44.4°C to which formalin [formaldehyde] and a non-ionic wetter have been added (MAFF, 1977). Fumigation under vacuum with hydrogen cyanide for 1 h at above 10°C gives good control of the nematode in bulbs, rhizomes and tubers, and especially asparagus roots and strawberry plants. In Japan, infestation in iris bulbs can be controlled by immersion in water containing formaldehyde at 43.5°C for 2-3 h, but some varieties may be injured during this treatment. In garlic bulbs, nematodes were controlled by drying at 34-36°C for 12-17 days (Fujimura et al., 1989). In Korea, D. destructor can be effectively controlled by flooding infested fields (Young and Seung, 1995).
Citrus medica skin extract killed 93.3% (71% after correction for controls) of the adult D. destructor after 72 h, and bacterial toxin of Erwinia nimmipressuralis [Enterobacter nimmipressuralis] strain 437 from beech killed 84.4% (68.8% after correction for controls) of D. destructor in 48 h (Abdel'-Khamed et al., 1977).
Preplanting treatments of potatoes by ultraviolet irradiation (60 times per month, each exposure for 10 min) decreased nematode infection more than 10 times (Bumbu, 1968).
Although Seinhorst (1949), Guskova (1966) and Olefir (1969) found some potato varieties showing resistance, Goodey (1956) and Moore (1971) found no marked resistance in the many commercial potato varies they tested.
In Kazakhstan, all 36 potato varieties tested were susceptible to D. destructor to varying degrees (German, 1970). In Belorussia, most of the varieties of potato tested were susceptible to infestation by D. destructor, but a few foreign varieties (such as Kardia, Patroness and Scutella) were fully resistant (Ivanova, 1983).
In Sweden, of 19 potato varieties studied, resistance was shown by Aquila and Elsa, and King Edward was less sensitive than Bintje (Andersson, 1971). All common commercial varieties of potato in Ireland are susceptible (Bulb Research Centre, 1973). In Ireland, tubers of Golden Wonder potato cultivar showed significantly more external symptoms (skin cracking) than King Edward, but the numbers of King Edward tubers with internal symptoms (sub-cutaneous 'pockets') were greater in 2 of the 3 years, the difference being significant in the third (Moore, 1978).
In Poland, among 186 potato cultivars tested, those found to be very slightly susceptible were Belg, Grom, Pimpernel, Robijn and Rode Star (normally considered resistant) - following cultivation experiments of several years, only 5% of the tubers became infected with tuber surface damage of up to 10%; and those found to be slightly susceptible were Alisma, Altgold, Arnika, Aura, Gracilia, Iduna, Leo, Murmanskij, Scaldia, Stelzner, Topaz and Ultimus - up to 10% surface damage in 10% of tubers. Among the wild potato species, three forms of Solanum commersonii, two of Solanum pinnatisectum and one each of a further seven species were not infected (Stefan, 1980).
Of 508 Ipomoea batatas varieties tested in a field infested with D. destructor in Shandong province of China, 68 varieties were found to have high levels of resistance (Wang et al., 1995). Of 143 accessions of sweet potato germplasm collected in the Yunnan and Guizhou provinces of China, 40 were resistant to D. destructor (Sun et al., 1994).
Control by crop rotation is difficult, as D. destructor is polyphagous. However, alternative non-host crops such as sugar beet can be used to check the nematode populations (Winslow, 1978). It is important to control weeds carefully because of the nematode's polyphagous habit. Populations increase under crops such as clovers and lucerne (Henderson, 1958) and persist in susceptible field weeds (Mentha arvensis, Sonchus arvensis). Crop rotation experiments in Lithuania showed that after monoculture of host plants such as buckwheat, carrot and lupins for 3 years in soil heavily infected with D. destructor, a crop of uninfected potatoes was obtained in the fourth year (Efremenko and Burshtein, 1975). Measures such as careful sorting of seed potatoes and early harvesting of potatoes, the use of rice and lucerne as preceding crops, or winter sowing of rye followed by late spring planting of potatoes, resulted in a considerable reduction of infestation (Adylova and Vasilevskii, 1983). The use of nematode-free seed potatoes is an essential component of any control programme.
In Central Asia, amide forms of nitrogenous fertilizers slightly reduced the prevalence of infection of seed potatoes by D. destructor, whereas ammonium-nitrate fertilizers favoured nematode multiplication (Artem'ev, 1976).
Application of fertilizers on the surface areas of infested potato tubers, at levels of nitrogen 360, phosphorus 240 and potassium 360 over 3 years, showed the lowest loss of tubers during storage. Untreated control tubers had the highest weight losses and the highest respiration rates (Glez, 1973). Solutions of nitrogen, phosphorus and potash fertilizers had an inhibiting and nematicidal effect on adults, larvae and eggs of D. destructor. Ammonium hydroxide, ammonium nitrate, ammonium sulphate and potassium chloride showed greatest activity; superphosphate was less active. Larvae were the most susceptible and eggs the most resistant to inhibition (Sepselev et al., 1973).
ReferencesTop of page
Adylova NA; Vasilevskii VN, 1983. The potato stem nematode at the collective farm "Sokh" in the Fergana valley and its control. (Materialy simpoziuma, Voronezh, 27-29 Sentyabrya 1983 g.). Voronezh, USSR: Vserossiiskii NII Zashchity Rastenii, 59-61.
Anderson RV; Darling HM, 1964. Embryology and reproduction of Ditylenchus destructor Thorne, with emphasis on gonad development. Proceedings of the Helminthological Society of Washington, 31:240-256.
Andersson S, 1971. The Potato Rot Nematode, Ditylenchus destructor Thorne, as a Parasite in Potatoes. Dissertation from the Agricultural College of Uppsala, Sweden.
Anon., 1972. Annual Report 1971-72. Dublin, Ireland: An Foras Taluntais.
APPPC, 1987. Insect pests of economic significance affecting major crops of the countries in Asia and the Pacific region. Technical Document No. 135. Bangkok, Thailand: Regional Office for Asia and the Pacific region (RAPA).
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Bridge J; Bos WS; Page LJ; McDonald D, 1977. The biology and possible importance of Aphelenchoides arachidis, a seed-borne endoparasitic nematode of groundnuts from northern Nigeria. Nematologica, 23(2):253-259
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