Abstract The aim of this study was to assess the efficiency of two intercrop species, Canavalia ensiformis and Desmodium intortum , to reduce weed growth, herbicide use and damage by the stalk borer Chilo sacchariphagus in sugarcane cropping system in Reunion. We compared six inter-row management techniques: four treatments combined the two intercrops Canavalia ensiformis or Desmodium intortum sown either early (between 0 and 2.1 months after sugarcane emergence) or late (between 1.3 and 3.7 months after sugarcane emergence), a treatment where no weeding was carried out on the inter-row, and a treatment with chemical weeding of the inter-row (CcWp). In all treatments, the sugarcane row was weeded chemically and manually. The six treatments were compared in a multilocal randomized block design with three localities, during one or two crop cycles depending on the locality. Desmodium intortum produced poor ground coverage in half of the trial x crop cycles and was therefore found unsuitable for use as an intercrop of sugarcane in our conditions. On the opposite, Canavalia ensiformis quickly covered the inter-rows, regardless of the sowing date. The Canavalia ensiformis intercrops allowed a reduction of herbicide consumption by 63% when sown early and by 28% when sown late, compared to the CcWp control treatment. Both Canavalia ensiformis intercrops caused a reduction of weed coverage on the inter-row similar or better than the chemical control. However, the early sown Canavalia ensiformis intercrop caused a 18.6 t.ha -1 yield loss compared the chemical control. No yield loss was detected with the late sown intercrop. A significant reduction of stalk damage by a 0.8-fold factor was observed in the early sown Canavalia ensiformis treatment.
Mansuy et al. (Tue,) studied this question.