Efficacy of manual seed sorting methods in reduction of transmission of rice and cowpea seed-borne diseases

Abstract

The production of rice and cow pea in Uganda is increasing in acreage rather than productivity. This is attributed to a number of factors, mainly seed-borne diseases. The farmers in Uganda mainly use farm saved seeds for planting. These seed are infected with a wide range of seed-borne pathogens, which result into diseases in the field. The objective of this study was to evaluate the effectiveness of sorting rice and cowpea seed by 15% salt solution density and by hand in reduction of transmission of seed-borne diseases, improvement of germination and yield in the field. Seed dressing with mancozeb (2%) and unsorted seed were included as control. Results indicate that the treatment methods used significantly (P<0.05) improved rice and cowpea seed germination, with the highest germination recorded in seed dressed with fungicides and sorted by 15% salt solution density than in those which are hand sorted. Rice blast and brown leaf spot were recorded on rice, while on cowpea, Cercospora leaf spots (Cercospora cruenta and C. canescens), septoria leaf spots (S. vignae and S. vignicola), brown blotch and sphaceloma scab (Elsinoe phaseoli) were recorded. The lowest disease incidences were recorded in plots planted with seeds sorted by salt solution (15%) density and seeds dressed with mancozeb than hand sorted seeds. Similarly, rice and cowpea yield was improved by seed dressing and 15% salt solution density, compared to hand sorted and unsorted seed. Therefore, 15% salt solution density can be used as an alternative to seed dressing in reducing transmission of rice and cowpea seed-borne diseases and improving rice germination and yield. This should be popularized among the farmers to improve rice yield in the farm.