Purple nutsedge (Cyperus rotundus L.) control with paper mulch in processing tomato

Purple nutsedge (Cyperus rotundus L.) is a serious weed capable of piercing polyethylene (PE) plastic mulch used in horticulture. A biodegradable plastic, PE and four different papers were tested for 2 years in fields highly-infested with C. rotundus in Zaragoza (Spain). All four papers were able to withstand all weed species. C. rotundus plants penetrated the biodegradable plastic mulch most, possibly because this material had least resistance to slow perforation. Differences in weed biomass between mulching materials were lower because of small size and weight of C. rotundus. Therefore all mulching treatments had a similar impact on weed biomass reduction 63 days after transplanting; biodegradable plastic had most biomass and papers the least, the differences being significant some years, only. Tomato yield was very similar for all mulching treatments and significantly higher than in the non-mulched plots. No effect of treatment was observed on fruit quality parameters. Commercial paper used as mulch without special additives can satisfactory control C. rotundus in processing tomato provided that climate is appropriate to maintain the paper dry during most of the time. Also the crop needs to cover the soil fast enough before the buried part of the mulch degrades allowing wind to lift and tear the mulch. ► Four different papers weighing between 50 and 200 g/m2 avoid the emergence of Cyperus rotundus. ► The paper mulch hinders the emergence of the other weed species, too. ► C. rotundus pierces PE and even more the biodegradable plastic. ► Tomato yield in paper mulched plots was the same than with PE and higher than in the untreated control.