Incidence of and yiel loss caused by maize rayado fino virus in maize cultivars in Ecuador

Abstract

Three sowing date trials, each planted with one cultivar, were performed to measure the natural in¬cidence of the Maize rayado fino virus (MRFV). The lowest incidences (1-6%) were obtained at the sowing dates normally practised in the tested regions. Earlier or later sowing dates had higher to much higher inci¬dences (up to 18 and 32%). Two cultivar trials, one with four cullivars and one with eight cultivars, showed sig¬nificant differences in incidence, ranging from 14.0% in ‘Iniap-160’ to 2.0% in 'Cadet-2’. In one trial with plots of 1000m2, the cultivar Iniap-122 was sown at three sowing dates. In each plot, plants that developed MRFV symptoms at the 8-10 leaf stage, at the 12-14 leaf stage and at the emergence of tassels were marked. Marked MRFV-al'fected plants were compared with non-MRFV-affected plants in their neighbourhood to estimate yield loss due to MRFV. The yield losses at the three sowing dates were 2.5, 1.6 and 4.8%, respec¬tively. It was concluded that the yield loss due to MRFV is quite small provided sowing is restricted to the nor¬mal sowing period.