CHARACTERIZATION OF RICE CROPPING PRACTICES AND MULTIPLE PEST SYSTEMSIN THE PHILIPPINES

A body of descriptors of the rice crop system was collected in a sampl e of farmers' fields in Central Luzon, Philippines, and these data wer e used to characterize cropping practices and pest constraints. The an alysis was conducted in four steps: (1) the time-dependent, quantitati ve information pertaining to pests (diseases, insects, and weeds) was integrated over crop development to account for injuries to the crop; (2) classes reflecting the various distribution frequencies were devel oped, and the quantitative information was categorized accordingly; (3 ) seven patterns of cropping practices (PR) and seven types of pest pr ofiles (PE) were characterized from two independent cluster analyses u sing a chi-square distance; (4) two contingency tables, yield by cropp ing practices (Y x PR) and yield by pest profile (Y x PE), were built and jointly submitted to correspondence analysis. Two first axes accou nted for 52.2% and 25.5% of total inertia, and were used to interpret the relationships among PR, PE, and yield. A path of increasing yield levels was associated with increasingly favourable production situatio ns, and was opposed to the accumulation of pest injuries. Cropping sea son, date of establishment, fertilizer input, and weed control practic es were identified among the components that drive production levels. Correspondences of specific key pests, or key pest combinations, with particular production levels and patterns of cropping practices were i dentified. The analysis suggested that weeds and stemborers may contri bute much to yield reduction. Sheath blight was closely associated wit h the highest yields, suggesting that (1) the disease did not contribu te to any yield reduction, and/or (2) it is particularly enhanced in p otentially high-yielding crops. In the latter case, control of sheath blight might result in even higher yields.