Deriving appropriate pest management technologies for smallholder tomato (Solanum lycopersicum Mill.) growers: A case study of Morogoro, Tanzania

Journal of Animal & Plant Sciences, 2010. Vol. 6, Issue 3: 663- 676. Publication date: 28/04/2010,The current standard farmer practice for insect pests and disease control in tomatoes is routine weekly pesticide sprays which are not always required. Field experiments were conducted at Morogoro, Tanzania to evaluate the effect of seven management practices (sub plots) on pest incidence and yields during May-September 2007 (normal production season) and October 2007 - February 2008 (off-season) using two determinate varieties CALJ and Tanya (main plots) in a RCBD with five replications. Practices involving intercropping with Vigna unguiculata or Cleome gynandra, application of fertilizer or mulch were severely infested by insects particularly thrips (Frankinlla occidentalis) which averaged 30 insects/plant at 64 days after transplanting. The standard and integrated pest management (IPM) practices led to similar low levels of insect pest and disease control though in the IPM only 3 pesticide sprays were applied compared to 10 for the standard practice. In the normal season, disease incidences of early blight (Phytophthrora infestans), late blight (Altenaria solani), leaf spot (Septoria lycopersici) and leaf curl were low (<10%) except for fertilizer and mulch treatment where incidences were close to 50%. The greatest fruit damage (>50%) was ascribed to Helicoverpa armigera. Purple nutsedge (Cyperus rotundus), the most dominant weed, was initially controlled by pre-transplanting application of Round-up® and mulch suppressed the growth of the dominant broadleaf weeds Digera muricata (false amaranth); Amaranthus spp (pigweeds) and Commelina benghalensis (wondering jew). In the normal season, tomato yields with current farmer practice were highest averaging 18.5 t/ha which was not significantly different (P=0.05) from mulch application (14 t/ha) followed by IPM (12.1 t/ha). Similarly, in the off-season crop, yields were highest and similar for mulch and standard practice (4.8 t/ha) followed by IPM (3.4 t/ha). Farmers selected mulch application and IPM for on-farm demonstration to verify production costs and benefits