Response of Some Cassava Varieties to Mononychellus tanajoa Bondar. (Tetrachynidae: Acarina) Infestation in the Lake Zone, Tanzania

Abstract

The study was aimed to determine the responses of 9 commercial and local cassava varieties to M. tanajoa and the environment in two different seasons (2014/2015, wet and dry) in the lake Zone. This was laid out in a Split plot design with varieties as sub plots and locations as main plots. Three field trials were conducted at three different locations, Ukiruguru (Latitude 020 43.156’ S, Longitude 0330 01.431’ E and elevation of 4000 m above sea level) N’gombe (Latitude 020 45.743’ S, Longitude 0330 01.838’ E and elevation 3888 m above sea level) and Kishiri (Latitude 020 48.694’ S, Longitude 0330 22.161’ E and elevation 4023 m above sea level) villages of Kwimba and Misungwi districts of Mwanza, respectively. These were replicated three times making a total of twenty seven plots. The treatments were allocated to a plot size of 36 m2 with 1 m path (boarder) between plots and 2 m between blocks. One stem cutting (30 cm long) was planted at a spacing of 1x1 m within and between rows giving a total of 10,000 plant population ha-1. This was allowed under natural infestation by the mites. The results indicated that the mites population and damage generally varied significantly (P= 0.05) among varieties, sampling dates and locations. In general, Kwimba recorded the highest population number of M. tanajoa while Ukiruguru had the highest root yield and number. The study shows that Kyaka appeared to be tolerant/resistant to cassava green mite while Liongo Kwimba, Naliendele, Suma and Namikonga were found to be most susceptible, respectively. Therefore, cassava varietal resistance has a significant effect on the population dynamics and damage of M. tanajoa in the Lake Zone, Tanzania.