EFFECT OF INTERCROPPING ON NEMATODES IN TWO SMALL-SCALE SUGARCANE FARMING SYSTEMS IN SOUTH AFRICA

Abstract

Berry, S. D., P. Dana, V. W. Spaull, and P. Cadet. 2009. Effect of intercropping on nematodes in two small-scale sugarcane farming systems in South Africa. Nematropica 39:11-33. Two trials were planted on sandy soils on small-scale grower farms to study the effect of intercropping on the nematode fauna, soil and plant fertility and sugarcane yield. Peanut (Arachis hypogaea) and sugar bean (Phaseolus limensis) were intercropped between the sugarcane rows in the first trial; velvet bean (Mucuna deeringiana) and sweet potato (Ipomoea batatas) were intercropped in the second trial. These practices were compared to a standard aldicarb (nematicide) treatment and an untreated control. In the first trial (irrigated sugarcane), peanut grew well as an intercrop, however, 70% of the sugar bean died before producing seeds. Intercropping with sugar bean had no effect on initial sugarcane stalk number whereas peanut reduced initial sugarcane stalk number by 30%. In the second trial (non-irrigated sugarcane), both velvet bean and sweet potato grew well as intercrops. Intercropping resulted in initial reduction in sugarcane stalk number of 30% for sweet potato and 70% for velvet bean. However, for both trials, and for all intercrops (except peanut), the sugarcane stalk number at harvest was the same as that of the control. Intercropping with velvet bean, peanut and sweet potato increased Meloidogyne javanica and Pratylenchus zeae infestation of the sugarcane sett roots; conversely, intercropping with sugar bean reduced nematode infestation. Intercropping with velvet bean, sugar bean and sweet potato had no effect on sugarcane yield, whereas intercropping with peanut reduced sugarcane yield by 22% and sucrose yield by 29%. Intercropping with velvet bean increased levels of some nutrients in the soil and leaves of sugarcane. These results show that intercropping can be used by small-scale growers to: manage nematodes (sugar bean), provide nutrients to the sugarcane crop (velvet bean), provide alternative food source and/ or income (sweet potatoes) and to improve the overall productivity of the land without being detrimental to sugarcane cultivation.