|Raid, R. -|
Submitted to: American Society of Sugar Cane Technologists
Publication Type: Abstract Only
Publication Acceptance Date: June 25, 2009
Publication Date: N/A
Technical Abstract: Orange rust of sugarcane, incited by Puccinia kuehnii, was first observed in Florida during June 2007 on one of the industry’s most important commercial cultivars, CP80-1743. This was the first report of this disease in the Western Hemisphere. It has since been reported in several other Central American and Caribbean Countries. Trials were initiated to investigate the feasibility of fungicides serving as an interim or supplementary management strategy until replacement of CP 80-1743 was completed. Thirteen different fungicide treatments were examined for their efficacy in controlling orange rust during the 2008/2009 growing season. Experimental units consisted of two rows of cane 15m in length, replicated four times. Fungicide treatments consisted of select candidates from two major classes of fungicides, the strobilurins (FRAC group 11) and triazoles (FRAC group 3), alone, and in combination or alternation. Fungicide applications were made using a CO2 backpack sprayer and were initiated following canopy closure (approx. 1.5-m ht) at 21 day intervals. Rust severity in the trial area was moderately severe, with severities in excess of 30% on the distal third of the fourth leaf beneath the top-visible-dewlap leaf in the untreated check. Results indicate that the strobilurin fungicides provided the highest level of control, followed by strobilurin/triazole combinations, and finally, the triazole fungicides alone. In separate trials using the strobilurin fungicide pyraclostrobin, fungicide treatments were demonstrated capable of reducing orange rust to levels sufficient to significantly reduce yield losses by as much as 40%. While economic factors will ultimately be an important consideration, levels of orange rust control obtained in these studies show promise regarding prospects for fungicides as a potential management tool.