Sommige aspekte van die invloed van Tagetes spesies op Nematode

Abstract

A short synopsis is given on the relation between nematodes and different Tagetes species with emphasis on the uncertain tics concerning the actual Tagetes effect. This is followed by a brief discussion on the purpose of the project and the methods and techniques employed in the investigation. Nematodes are identified to genus level only, except in the case of Meloidogyne where species are identified. The relevant nematode groups Meloidogyne, Heplolairuidae, Tylenchidae, Aphelenchidae, Dorylaimidae and the Rhabditida are compared under different treatments. Experiments were carried out in micro-plots under field conditions. Similar experiments were simultaneously carried out in pots in the glass-house under controlled conditions. Different varieties of Tagetes erecta (Marigolds ) and T.minuta (Khaki weed) were cultivated in the infested soil for t en months. The effect of these plants on t he nematode population was assessed by comparing the nematode populations in the treated soil with the nematode population in fallow soil as a control. After treatment a host plant , Lycopersicon esculentum (Tomato), was cultivated in the treated soil and in fallow soil for three months and assessed for nematode damage. Changes in the nematode population in the soil were also assessed. Correlation be tween the plant growth and infection was investigated. A study was also made of the effect Tagetes has, as a green manure, on the nematode population in the soil and the infestation and growth of L. esculentum thereafter. The effect of Tagetes , as green manure, on the nematode population in the soil : as well as infestation and growth of J, esculentum cultivated after treatment, is compared with the effect of Crotalaria juncia (Sunnhemp) and Pcnnisetum typhoides ( Babala). The practical value and application of the different treatments in agriculture a re discussed.