|Potato Rot Nematode||Classification||Hosts|
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Temperate regions; Europe, North America (Marin County, California), South Africa, China.
B-rated pests in California. Causes severe damage to sweetpotatoes in the Shandong province of China (Wang et al., 1995).
Obligate parasite of higher and lower plants.
Ditylenchus destructor usually feeds as an endoparasite below ground
on tulips and other bulbs, but can also feed on fungal hyphae.
Iris, tulip and and other ornamental bulbs, sweetpotato.
Sugarbeet, carrot, potato, peanut; weeds and fungi as alternate hosts.
For an extensive list of host plant species and their susceptibility, copy the name
select Nemabase and paste the name in the Genus and species box
Ditylenchus destructor does not have the J4 resistant stage seen in D. dipsaci. It does not become anhydrobiotic and form eelworm wool.
The nematode can survive on weed and fungal hosts; does not withstand desiccation.
Nematode enters potato tubers through lenticels and forms a white, mealy spot. Tissues shrink; brown lesions appear; outer skin becomes papery. Secondary invasions occur; general rot may also occur.
In Marin County, California, infestation first occurred in 1968 in potatoes following iris bulbs. No above-ground symptoms on potatoes, but there were pin-hole lesions on surface of tubers.
Nematode secretes pectinase enzyme and proteases to digest starch and proteins; this causes cell disintegration.
Ditylenchus dipsaci also attacks potato tubers and produces the typical sunken lesions and dry-rot condition. Lesions produced by this nematode are usually deeper than those produced by D. destructor. Secondary fungal and bacterial invasion can also occur in lesions caused by D. dipsaci.
Black lesions appear; leaves are poorly developed and yellow-tipped; stem infestations can occur, but are rare.
Important pest on the 500,000 acres of peanuts in South Africa where it reduces yield by 12% and reduces quality by discoloring seed testa.
Discolored seed is downgraded into lower quality (and value) classes: Export>Domestic>Processing. The price changes associated with downgrading are much more significant than the direct yield loss.
Causes water loss and cell shrinkage in sweetpotato tubers; also reduction in
size and number of starch grains (Sun et al, 1998; Wang et al, 1995).
Start with clean seed potato tubers.
Crop rotation is not effective as the species is polyphagous.
Host Plant Resistance, Non-hosts and Crop Rotation alternatives:
For a list of plant species or cultivars (if any) reported to be immune or to have some level of resistance to this nematode species, copy the name
select Nemabase Resistance Search and paste the name in the Genus and species box
Host-plant resistance in potato has been explored on a limited scale. Sixty eight of 508 varieties and accessions of sweetpotato showed resistance in China (Wang, 1995). Xylem parenchyma had thicker, lignified walls in resistant varieties (Lin, 1996)
Soil fumigation is rarely economical. However, control was achieved in the Marin County infestation by using ethylene dibromide (EDB) applied at a rate of 90 lbs/acre, with chisels 12" apart.
Early harvest of peanuts avoids some economic loss in South Africa. Cultivars are selected that allow early harvest in specific biogeographic regions (Venter et al., 1991).
Lin, M.S., L.M. He, L. Wen and Z.D. Fang. 1996. Mechanism of morphological structure of sweet potato resistance to root rot nematode (Ditylenchus destructor). Scientia Agricultura Sinica 29:8-12.
Sun, J.H., D.L. Peng, K.L. Yu, P. Bi, and Y. K. Peng. 1998. SEM study on tissue pathology of stem nematode disease of sweet potato. Acta Agriculturae Boreali Sinica 13:101-105.
Venter C., D. DeWaele, and A.J. Meyer. 1991. Reproductive and damage potential of Ditylenchus destructor on peanut. Jourrnal of Nematology 23:12-19.
Wang, Q.M., C.X. Chang, J.J. Wang and G.H. Xi. 1995. Identification of resistance to stem nematode in sweetpotato. Crop Genetic Resources 2:36-37.