This work aimed to measure the effects of permanent and specific interference of S. polyacanthus on CP 74-2005 sugarcane cultivar in Monte Rico (27º21'S-65º36'W) (Tucumán province, Argentina). A complete randomized experimental design was carried out on a naturally infested sugarcane field. Each 64 m²-plot consisted of four ten-meter long furrows. The effects were measured at three infestation levels: high (more than 5 pl m-2), medium (1-4 pl m-2) and low (less than 1 pl m-2) . The measurements were taken on two central furrows in each plot. Height was taken by means of the average of ten measurements per infestation and per replication. Crop yield was evaluated by means of one sugarcane sample per plot, at the same place. The interference effects on height at different infestation degrees were highly significant in relation to the control, reaching 48.58% of losses in low infestation. In high infestation, there were significant losses of stem number, at the different levels, reaching 61.87%. Sugarcane yield per hectare presented a 43.89% loss under medium infestation. Sugar production presented 42.28% and 20.38% of losses in high and low infestation, respectively.
weed; Cucurbitaceae; interference; Saccharum spp.
