Major weeds of Ecuador IV. Coffee plantations in Jipijapa

Coffee is a crop of economic importance in Ecuador, grown in area of 199 215 ha, 38,6% of it in Canton of Jipijapa, located in the south of the province of Manabí. Coffee here is grown by small farmers, who spend who spend little annually for the maintenance of plantations. One of the main constraints for getting optimal crop yields is the presence of weeds, which affect water stress during dry spells, and bring about deficient plant uptake of essential nutrients. Weeds are not usually properly controlled in all areas of this crop. Some farmers eliminate weeds twice or three times a year, others do that only once. The most common control method is hand hoeing, but some growers use foliar-applied herbicides, any of these practices are commonly carried out without knowledge of prevailing weed species.  Suitable weed management strategy should include data about main weeds and their biology during dry and rainy seasons in Jipijapa. To this end, in 15 ha  of coffee plantations during 2014 dry period and in another 15 ha during 2015 rainy one, weed cover and species present were visually evaluated using a scale 0-5, where 1- up to 5% weed cover and 4-more than 50%. These values were processed to determine Absolute and Relative Frequencies, average weed cover and finally Severity Infestation (SI). A total 39 weed species belonging to 19 families were found in both seasons, mostly broadleaves plants, while grasses were found in less shady spots of the plantations. The prevailing weed during rainy period appears to be Senna occidentalis followed by Commelina erecta, Laportea aestuans, Alternathera flavescens and Xanthosoma spp., while during dry season, the fern Pteridium aquilinum was the leading species followed by perennials Alternathera flavescens and the C4 grass Megathyrsus maximus. The species found only responded to the humidity conditions in each season and not to the effect of a certain control measure. Most of the evaluated plantations show poor crop management, scarce crop plant density, and even coffee planted in favor of the slope. Improved plantation management is the key measure to reduce the weed presence of weeds. In the rainy season, with more weed abundance, two early weeding operations, with an additional one later are advisable, while in the dry season, in the case of plantations with adequate shade, one weeding may satisfactorily reduce the weed presence. Perennial Geophila macropoda, found during rainy season, is a potential living cover in coffee plantations since it may help to reduce soil erosion and smothers weeds.