Effects of an antagonistic plant, African marigold, Tagetes erecta L. on the population density of Pratylenchus vulnus (Nematodes) causing root lesion of strawberry
1992 Volume 38 Pages 146-148
Details
1992 Volume 38 Pages 146-148
The Pratylenchus vulnus infested soil was collected from the field and mixed evenly to minimize the variation in nematode density. The mixed soil was then put in 60 plant pots (about 5.3 liter). Three experimental plots were set, consisting of 20 pots which were buried at a distance of 20 cm in the row. Marigolds var. African tall and strawberries var. Toyonoka were individually planted on 10 July 1991 in the pots of each plot while the other 20 pots remained without any plants as a control plot. A sample of 20g soil was taken from each of 4 pots in the plots every two weeks during summer and nematodes were extracted with Baermann funnels. The density of P. vulnus averaged 998. 9 (±630. 2 SD) just before the experiment. Irrespective of the treatment, the mean density of nematodes rapidly decreased and was highest in the strawberry plot during summer. However, from late August the nematode density decreased slowly in the marigold plot but not in the control and strawberry plots. The density was significantly lower in the marigold plot compared with those in the control and strawberry plots when a sample of 20 g soil was taken from each of 60 pots at the final sampling date two weeks before transplanting strawberries. In the marigold plot nematode numbers decreased to 5.6% of the initial density while in the control and strawberry plots the decrease was to 13.0 and 14.6%, respectively. During summer a decrease in nematode densities was found in all plots, suggesting that climatic factors such as temperature may affect nematode numbers. On the other hand, the difference in nematode density in the marigold plot between late August and early October indicates that marigolds may suppress only 38% of the nematode population. From these results it is concluded that marigolds, African tall, are not effective in controlling P. vulnus in strawberry fields.
