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Title: The effect of thionazin on nematodes
Author: Kondrollochis, Margarita
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1971
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Thionazin applied as a single dip to narcissus and tulip bulbs infected with Ditylenchus dipsaci caused a great reduction in the nematode population after the first growing season, but the population re-established itself in bulbs left down for two growing seasons. Thionazin persisted in narcissus bulbs in gradually decreasing amounts for about six months during which time the nematode population declined gradually and bulbs were protected against further invasion. Nematodes migrated from treated bulbs in numbers which were proportional to the bulb population and re-invaded when the compound had been metabolised. The application of a drench during the first spring following dipping enhanced protection, and was particularly effective on sandy acid soils where the stability of thionazin is high. Combined treatments of thionazin with hot water treatment improved nematode control but a few nematodes still survived from heavily infested bulbs and increased in the second growing season. Observations on the effect of thionazin on D.dipsaci "in vitro" revealed that while there was no mortality unless the period of exposure was greatly extended, thionazin had a rapid effect on nematode activity causing a reduction in the rate of movement which was greater at higher concentrations and exposures. When returned to water D.dipsaci recovered normal activity the recovery being slower with greater inhibition. A similar reduction in activity after exposure to thionazin was observed in Aphelenchus avenae and Panagrellus redivivus. Onion seedlings were protected against invasion by D.dipsaci by as little as 0.1 ppm thionazin, and the rate of invasion reflected the rate of movement after treatment in thionazin. Observations on the feeding of A.avenae in the presence of thionazin revealed a rapid disruption of the co-ordinated feeding process leading to inhibition of feeding which demonstrated that thionazin has a contact action.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available