RESUMEN
Successive plantings of sweet corn in Orange Walk District, Belize (<200 m ASL) were observed to be performing poorly. Plants were stunted with shortened upper internodes, over-production (proliferation) of ears, and chlorosis of ears and leaf bases. Plants of hybrid white corn in Cayo District (<200 m ASL) had leaf-base chlorosis, mid-vein reddening, chlorotic bands on the leaves, and die-back of leaf tips: symptoms attributed to infection by the corn stunt complex (CSC) pathogens. Spiroplasma kunkelii was detected in symptom-bearing leaf-base samples of white corn but not sweet corn, using a specific F(ab')2 protein-A enzyme-linked immunosorbent assay (ELISA; D. Gordon, Ohio). Polymerase chain reactions with maize bushy stunt (MBS) phytoplasma-specific primers (1) resulted in amplification products of the expected size (740 bp) when DNA extracts from either sample type were used as template. DNAs from apparently healthy sweet or white corn from the field, or from glasshouse-grown sweet corn, did not yield this product. MBS and S. kunkelii are transmitted by leafhoppers of the genus Dalbulus, often simultaneously with maize rayado fino virus, the other CSC component (not tested for in this study). All the sweet corn varieties examined had a high incidence of the symptoms, suggesting that they are highly susceptible to one or both of the CSC mollicutes. With the increase in area dedicated to maize production and successive year-round plantings, the potential for spread and increased incidence of MBS or CSC in Belize is considerable. Reference: (1) N. A. Harrison et al. Plant Dis. 80:263, 1996.