Sugarcane Mosaic Distribution, Incidence, Increase, and Spatial Pattern in Louisiana

Area of Science:

• Plant pathology
• Virology
• Agricultural science

Background:

• Sugarcane mosaic, historically significant in Louisiana, is caused by sorghum mosaic virus (SrMV).
• Resistance breeding has lowered disease incidence in commercial sugarcane cultivars.
• Recent detections in experimental clones raised concerns about current disease distribution and prevalence.

Purpose of the Study:

• To assess the current distribution and incidence of sugarcane mosaic disease in Louisiana.
• To identify the primary source and transmission dynamics of SrMV in experimental sugarcane fields.
• To evaluate the disease progression in a newly released cultivar and experimental clones.

Main Methods:

• Field surveys were conducted from 2016 to 2018 in sugarcane breeding trials.
• Reverse transcription PCR (RT-PCR) was used to detect SrMV in symptomatic and asymptomatic plants.
• Spatial analysis (runs analysis) was employed to assess disease aggregation patterns.

Main Results:

• Mosaic symptoms and SrMV were detected in a new cultivar (HoCP 09-804) and nine experimental clones.
• SrMV was confirmed in 100% of symptomatic and 0.3% of asymptomatic samples.
• Infected seed cane was identified as the likely primary source, with limited aphid transmission observed.

Conclusions:

• Sorghum mosaic virus remains a significant pathogen in Louisiana sugarcane breeding programs.
• Infected seed cane is the main driver of disease spread, not aphid transmission under current conditions.
• Disease management strategies should focus on seed cane quality and monitoring experimental plots.