Interference periods of weeds in the sugarcane culture: I - Purple nutsedge

The objective of this research was to study interference periods between weeds and sugarcane culture in a experimental area located in Pradópolis, São Paulo State, Brazil. In these experiment, sugarcane was planted in May of 1995, and harvested 15 months later. The climatic conditions in São Paulo State during the months that follow sugarcane planting in the experiment (normal time when growers plant sugarcane), are characterized by negative balance of rain and evapotranspiration and mild temperatures, and the rainy season starting only four months after planting time. According to the results, it was concluded that, in the experiment where purple nutsedge (Cyperus rotundus) was the major infesting weed, sugarcane tolerated only 41 days, after planting, without interference by the weed, due to probably a greater competitive ability and allelopathic effect that have been attributed to this weed during the earlier stages of sugarcane development, interference starts right after initial sugarcane sprouting. On the other hand, purple nutsedge is very sensible to crop canopy shading, and low temperature, so the competition ended at only 22 days after planting (DAP).

Saccharum officinalis; weed; competition; Cyperus rotundus