Incidence of and yield 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 incidence 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 incidences (up to 18 and 32%). Two cultivar trials, one with four cultivars and one with eight cultivars, showed significant differences in incidence, ranging from 14.0% in 'Iniap-160' to 2.0% in 'Cadet-2'. In one trial with plots of 1000 m 2 , 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-affected 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%, respectively. It was concluded that the yield loss due to MRFV is quite small provided sowing is restricted to the normal sowing period.

Entomofauna Associated with Corn Cultivation and Damage Caused by Some Pests According to the Planting Season on the Ecuadorian Coast

“…Dalbulus maidis is considered an important pest affecting corn cultivation due to the transmission of various pathogens such as spiroplasmas but mainly for vectoring the Maize rayado fino virus (MRFV) [13]. This viral disease reduces corn yield and has been reported to cause losses in corn crops in the Andean region of Ecuador [30]. Although this virus has not been reported for the Ecuadorian coast, the presence of the virosis in the country, as well as the presence of its main vector, D. maidis, and other leafhoppers, make these insects potential entomological problems for corn production on the Ecuadorian coast.…”

Untitled

“…Other viruses such as Maize necrotic streak virus (MNeSV), Maize rayado fino virus (MRFV) and Maize fine streak virus (MFSV) also cause corn diseases. In Central and South America, MRFV causes the "rayado fino" or "achaparramiento" of maize, one of the most known diseases in corn (Vasquez & Mora, 2007). In Mexico, several viruses that infect maize have…”

Control of Virus Diseases in Maize

“…Maize rayado fino was identified in the late 1960s in El Salvador and Costa Rica, and it continues to be one of the most important virus diseases of maize in parts of Mexico, Central, and South America (Gamez, 1969(Gamez, , 1976Vasquez & Mora, 2007). Maize rayado fino is caused by Maize rayado fino virus (MRFV; family Tymoviridae; genus Marafivirus).…”

“…Maize rayado fino symptoms include small chlorotic spots on young leaves that become elongated and more numerous along leaf veins as the plants age. Infected plants are stunted and grain yield is reduced (Bustamante, Hammond, & Ramirez, 1998;Toler, Skinner, Bockholt, & Harris, 1985;Vasquez & Mora, 2007). Maize rayado fino and achaparramiento are problems where overlapping maize crops provide a reservoir of pathogens and continuous food and breeding hosts for D. maidis.…”