Field infection of virus-free sugarcane by Sugarcane yellow leaf virus in south Florida
Wardatou Boukari: University of Florida
<div>Sugarcane yellow leaf virus (SCYLV), the causal agent of sugarcane yellow leaf, is widespread in Florida. This virus is spread by the aphid vector <em>Melanaphis sacchari</em> or by infected seed cane. We aimed to determine the rate and timing of sugarcane infection under field conditions. Two field trials were set up, one on organic soil and one on mineral soil. Each trial consisted of plots planted with either virus-free or virus-infected seed cane of two commercial cultivars. SCYLV prevalence was determined during three consecutive crop seasons by leaf-blot immunoassay. Virus prevalence varied from 83% to 100% in plots planted with infected seed cane regardless of cultivar, location, and crop season. SCYLV was not detected in virus-free plots at first sampling date, but plants in these plots became progressively infected on organic soil in plant cane and first ratoon crops. Sugarcane remained virus-free on mineral soil in plant cane crop and became infected only in first ratoon crop. By the end of the second ratoon crop, the highest virus prevalence was 33% in sugarcane grown on organic soil whereas only 5% of plants were infected in sugarcane grown on mineral soil. Differences in sugarcane infection by SCYLV between crop seasons and locations may be related to variation in aphid populations and activity. However, low virus prevalence after three crop seasons suggests that planting virus-free seed cane should limit the impact of SCYLV on sugarcane production in Florida.</div>
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