BP Singh

Treatment Schedules for Eradication of Nematodes from Germplasm 219violets, muscari, gladiolus and potatoes. The chief aim of much ofthis work was to test the tolerance of the nost plant to hot water.Several refinements have improved the efficiency of hotwater treatment for control of D. dipsaci in narcissus bulbs andlessened the risk of damage to the bulbs. These include early lifting,storage at 25-35°C followed by presoaking, immediately before hotwater treatment, use of a wetter and formaldehyde in the treatmenttank, use of anti foaming agents and increasing the temperatures.Bulbs may require drying after treatment to avoid hazardsin subsequent storage. Further the treatment has limited usefulnessbecause of certain drawbacks. The margin between killing ofendoparasitic nematodes and phytotoxicity is usually very narrow.HWT can be applied only when bulbs are dormant.(b)Treatment for the rootsHWT is also used to control nematodes on grapevinerootlings, Meloidogyne javanica in South Africa (Smith, 1982) and M.javanica and the citrus nematode in Australia. Dormant rootlingsare treated for either 15 min. at 50°C or 5 min. at 52°C in SouthAfrica and for 5 min. at 51°C in Australia. Immediately after HWTthe rootlings are plunged into cold water to minimise damage tothe plants.Control of Pratylenchus penetrans in raspberry root cuttingswas attempted by a chemical bare root dip in several chemicals andby a hot water treatment. Only the hot water treatment waseffective in killing the nematodes without injuring the plants. Fivecultivars were tested with hot water. The nematodes wereeliminated without injury to the cultivars (McElroy, 1973). Thetreatment schedules developed in the Plant Quarantine Lab atNBPGR., for salvaging germplasm are mentioned in Table l.(c)Treatments for the tubers, corms, stools and suckersHot water treatment can be used as a preventive measure tocontrol endoparasitic nematodes that are disseminated on or incorms, tubers, rhizomes and other planting materials. An applicationof hot water treatment for control of Aphelenchoides ritze11labosi inchrysanthemums is by treating the dormant stools. Here theproblem is simpler than with bulbs, since one is dealing withnematodes that are either external contaminants or occur within