Weed Survey of Small-Scale Vegetable Farms in Ormoc City, Philippines with Emphasis on Altitude Variation

Abstract

Weeds are critical in vegetable production because they reduce yields. Farmer and field weed surveys in low and high elevation vegetable production areas in Ormoc City were conducted to determine whether differences in weed problems exist in low and high elevations and to investigate the effect of altitude on the abundance and diversity of weed vegetation. Thirty respondents were interviewed and 30 field sites were sampled. Farmers practiced different cropping systems such as monocropping and multiple cropping and weed management practices used were mainly tillage and hand weeding. Farmers’ perception of the most problematic weed species did not always correspond to actual weed incidence. Frequent field disturbance, use of herbicides, and rotation of crops may have led to changes in weed flora. In the field survey, a total of 44 weed species were identified, in which 41 and 14 species were recorded in the low and high elevation areas, respectively. Based on the importance value index (IVI) values, Cleome rutidosperma, Cyperus rotundus, Cynodon dactylon, Phyllanthus amarus, and Ageratum conyzoides were the most important species in the low elevation while A. conyzoides, Galinsoga parviflora, Commelina diffusa, Eleusine indica, and Drymaria cordata were dominant in the high elevation. Diversity indices (Margalef’s richness index and Shannon diversity index) showed that elevation influenced the distribution of weed vegetation. Moreover, similarity index of weed species revealed a value of 15.38% between the low and high elevation areas which indicates that the sites exhibited different weed communities.