Distribution and Identification of Nematodes in Tomato Farmers’ Fields in the Selected Semi-Arid Climates of Central and Northern Tanzania

Aims: On farm assessment of nematode infestation in tomato farmers’ fields was carried out by scoring their incidence and severity in the selected semi-arid climates of central and northern Tanzania. Out of 25 plants assessed from each farmer’s field, 5 plants were uprooted and scored using a 1-5 galling index. Uprooted disease plant and soil samples were collected for laboratory assessment. This study revealed a degree of variation in the mean incidence and severity of nematode infestation along the study areas. Meloidogyne, Scutellonema and Helicotylenchus were identified nematodes of economic importance. Meloidogyne was the most predominant nematode across all the production areas. It was therefore advised that farmers’ management practices be improved alongside an establishment of varieties that could withstand pressure of nematodes as revealed from present study.

Study Design: Study was cross-sectional assessment survey.

Place and Duration of Study: This study was conducted in farmers’ fields in 22 villages from peri-urban areas of Dodoma Municipality, Kongwa, Babati and Kiteto districts as the main tomato growing areas in the central and northern districts of Tanzania in 2013/14 and 2015/16 production seasons.

Methodology: On farm assessment of nematode was taken by scoring incidence and severity of their infestation. From each village, four tomato farmers’ fields were randomly selected for an assessment. Out of 25 plants selected from each field, 5 plants were uprooted to 15-30 cm soil depth for nematode scoring. Gall score for severity determination of nematodes was a 1-5 galling index i.e. 1 (no galling) to 5 (severe galling). Incidence % of nematodes was analyzed to low, medium, or high, if (≤25%), (25% < to 50%), and (50% < to 100%) of tomato roots were infested with nematodes respectively.

Results: The average mean incidence of nematodes along the selected semi-arid climates of central and northern Tanzania was 36.1% with the highest mean incidence (48%) discovered in Kongwa district. Kiteto and Babati districts had the next highest mean incidence by 38.3 and 34.3% respectively. The lowest mean incidence (23.8%) was discovered in peri-urban areas of Dodoma Municipality. The mean incidence had an impact on the average mean severity (2.7) of nematode infestation and the mean severity in the specific district along the study areas. Kongwa district that had the greatest incidence along the study areas was noted with the highest mean severity by 3.8. Closely, was Kiteto by 3.0 which had greater mean incidence than two other districts; Babati and Dodoma Municipality whose mean severity were the lowest by 2.3 and 2.2 respectively. Furthermore, Meloidogyne was discovered the most predominant nematode along the selected study areas by 99.3%. Tylenchulus, Pratylenchus, Helicotylenchus, Aphelenchoides and Rotylenchus were revealed less common nematodes by 0.7% in total.

Conclusion: It was advised that farmers’ management practices be improved alongside an establishment of more varieties that could withstand dry climates and doing well in pressure of nematodes within surveyed areas.