The broad objectives were to better understand the biology of <i>Meloidogyne javanica</i> and to seek cultural and non-chemical control methods of controlling it in tobacco and vegetable rotations in Tanzania. In pot trials <i>Tagetes erecta, Sesame orientale, Arachis hypogea</i> and <i>Zea mays</i> were all shown to be non or poor hosts of <i>M.javanica</i>. These were tested as rotational crops in one or both of two field trials. The core of my work was two rotational trials which extended over three seasons. In the first and third seasons of the field trials susceptible crops (tobacco or tomato) were grown uniformly in all plots. In the second year the various rotational treatments were applied. In both trials <i>Crotolaria ochroleuca</i> greatly reduced <i>M.javanica</i> and increased yields in the third season. The role of root exudates in the effectiveness of <i>T.erecta</i> and <i>C.ochroleuca</i> was studied in pots. Exudate from <i>T. erecta</i> controlled <i>M.javanica</i> on tomato provided it was applied at or before juvenile invasion. That from <i>C.ochroleuca</i> had no effect. In the tomato trial a weedy fallow maintained a substantial population of <i>M.javanica</i> and its weed hosts were examined in a dry season survey of tobacco fields. Two thirds of these which were commonly found were hosts. Solarisation was tried as an additional means of controlling <i>M.javanica</i>. Water bath experiments suggested temperatures above 50<SUP>o</SUP>C were needed for rapid killing of <i>M.javanica</i> eggs. Such soil temperatures were not achieved even under polythene where the maximum was 45<SUP>o</SUP>C. Even so, eggs of <i>M.javanica</i> were killed over 2-3 weeks probably by a combination of temperature and drying. In other temperature studies the base temperature for development of <i>M.javanica</i> was found to be 12.8<SUP>o</SUP>C and thermal constant at 356<SUP>o</SUP>C days. In the continuous tomato plots in the field trial the incidence of <i>M.javanica</i> decreased in the third year associated with a high level of infection with the bacterial parasite <i>Pasturia penetrans</i>. In pot <i>P.penetrans</i> showed promise in reducing infection by <i>M.javanica</i>.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:593019 |
| Date | January 1992 |
| Creators | Madulu, J. D. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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