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Golden NematodeTwo species commonly called "golden nematode" produce cysts on potato roots: Globodera rostochiensis (the actual 'golden nematode') and Globodera pallida (the pale cyst nematode). Both species cause damage to potatoes, tomatoes and eggplant and will also attack other members of the Solanaceae plant family, such as nightshade.In Canada, the golden nematode (G. rostochiensis) occurs only in Newfoundland and Labrador and the central Saanich Peninsula (municipality of Saanich) on Vancouver Island, British Columbia. It was also recently found in Quebec (August 2006). The pale cyst nematode, G. pallida, is present in Newfoundland. Strict quarantine measures are in place to prevent the spread of these pests. RegulationsThe British Columbia Plant Protection Act, Golden Nematode Regulation (Reg. 253/79) prohibits the transportation of soil and plants, or farm equipment with soil, either within the municipality of Saanich or from the municipality of Saanich to other parts of the province. As a result, all equipment contaminated with soil leaving the infested area in central Saanich must be pressure-washed to remove soil.The Canadian Food Inspection Agency (CFIA), under Directive 96-05 prohibits importation of all potatoes from infested areas of the United States. SymptomsPlants are stunted and yellow, and may die off completely, usually in patches in the field. Potato tubers from affected plants are usually small, but show no other symptoms.The symptoms of golden nematode damage are similar to those caused by other pathogenic soil-borne nematodes and other soil factors, such as compaction, flooding, drought, herbicide injury or nutritional deficiency, so are not diagnostic. A laboratory examination is needed to positively identify this nematode pest. On heavily infested plants, the cysts of the golden nematode can often be seen on the roots with the naked eye. Cysts are white to golden to dark brown in colour, shiny and round and are attached to the root by a short stalk.
Life CycleThe golden nematode cyst is actually the swollen body of a dead female nematode. Each cyst contains up to 500 nematode eggs that hatch when they are near the roots of a host plant. After hatching, young (juvenile) nematodes, also called larvae, enter the plant's roots where they feed on plant nutrients and grow to maturity. Male nematodes then leave the root. Females extrude from the roots but remain attached and at this stage appear as tiny, white, swollen objects. They are fertilized by the male nematodes in the soil, which then die. After fertilization, the females produce eggs and also die, forming a hard wall around the eggs with their bodies. This is the cyst. Cysts are white at first, but gradually darken to a golden yellow or dark brown colour. Cysts detach from the roots and can survive up to 20 years or longer in soil.Hosts and Geographic RangeAlmost all plants in the Solanaceae family are hosts of golden nematodes. They do not feed or reproduce on other plant species. However, cysts can be transported in soil from infested areas.The golden nematode is widely distributed in Europe, Africa and Asia and occurs in many countries of South America. In North America, it occurs in parts of Mexico, on Long Island in New York State and in Canada only in Newfoundland and the central Saanich Peninsula of British Columbia, where it was found in 1965. It was also found in Quebec in 2006 on one farm. Since 1965, rigorous adherence to strict sanitation measures has prevented the spread of this nematode in soil to other parts of British Columbia and Canada. The pale cyst nematode is found in many places where potatoes are grown, including Europe. It was reported for the first time in Idaho in April, 2006. Prior to that report G. pallida was only known to occur in Newfoundland.
Further Information:
August 2006
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