Yellow Leaf Disease In Sugarcane

By Andre Gama, Plant Pathologist LSU AgCenter Kenneth Gravois, Sugarcane Specialist LSU AgCenter Al Orgeron, Resident Coordinator Sugar Research Station LSU AgCenter Atticus Finger, Director of Research American Sugar Cane League Wilson Judice, Agronomist American Sugar Cane League Katie Richard, Agronomist American Sugar Cane League

Yellow leaf disease was first reported in the Louisiana sugar industry in the late 1990s. It is caused by the sugarcane yellow leaf virus, which is transmitted by the sugarcane aphid (Melanaphis sacchari). Since then, the incidence of yellow leaf disease has remained low, primarily because of Louisiana’s healthy seedcane program. The use of tissue culture-derived seedcane has helped eliminate or suppress many sugarcane diseases in the state. Research has shown that yellow leaf disease can reduce sugar yield at low levels, although not all sugarcane varieties are negatively affected. In the past four years, yellow leaf disease has become more prevalent in Louisiana. The reason for this increase is not yet fully understood. Although sugarcane aphid populations have declined over the last decade, the incidence of yellow leaf disease has risen, including in tissue culturederived seedcane produced by both commercial seedcane companies. In late 2024 and into 2025, the Louisiana sugarcane research group recommended changing the seedcane certification standard for yellow leaf disease from a 10 percent to a 20 percent infection threshold. This adjustment was intended to allow for continued access to healthy seedcane while targeted research is conducted and disease trends are closely monitored. The Seed Commission of the Louisiana Department of Agriculture and Forestry (LDAF) approved this change. In the summer of 2025, LDAF sampling showed that yellow leaf disease incidence exceeded the new 20 percent threshold in approximately 20 percent of seedcane fields eligible for certification. Based on this data, the Louisiana sugarcane research group makes the following recommendations for 2025: 1. Seedcane fields that meet LDAF certification standards will continue to be sold as certified seedcane. 2. Seedcane fields with yellow leaf disease incidence between 20 and 50 percent may be sold as noncertified seedcane. 3. Seedcane fields with yellow leaf disease levels exceeding 50 percent should not be sold. The research group considers this a manageable risk as targeted studies continue. Maintaining access to healthy seedcane remains a priority. Other diseases, including ratoon stunting disease.(RSD), mosaic, leaf scald, and smut, continue to pose a greater threat to sugar yields in Louisiana. These recommendations apply only to the 2025 season. The situation will be reassessed in early 2026.