|Raid, R - UNIV OF FLORIDA IFAS|
|Irey, M - U S SUGAR CORPORATION|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: April 20, 1997
Publication Date: N/A
Technical Abstract: Sugarcane rust (Puccinia melanocephala Syd. & P. Syd.) introduction caused devastating losses in Florida. Several major cultivars (CP 63- 588, CL 41-223, and CP 65-357) were susceptible. Growers subsequently increased acreage of CP 72-1210, a cultivar which was reported as resistant at release in 1982. By 1986, CP 72-1210 occupied 61% of Florida's sugarcane acreage. A widespread rust epidemic on CP 72-1210 in 1987 provided evidence of physiological variant of the pathogen. Similarly, virulent rust variants were observed on formerly resistant CP 78-1247 and CP 74-2005 in 1988 and 1989, respectively. Research demonstrated increased rust severities as soil pH decreased. Observations also revealed positive correlations of rust severity and cachaza (mill mud) field applications. Rust severities increased several fold by increasing the area planted to a susceptible cultivar. These observations have led to several recommendations regarding rust management strategies: 1) Plant resistant cultivars wherever possible; 2) Diversify cultivar holdings; 3) Avoid planting large contiguous plantings of any one cultivar; 4) In particular, plant resistant cultivars on low pH soil; and 5) Avoid planting known susceptible cultivars on fields treated with cachaza. Overall, rust has been of minor importance during the past six years. Rust resistance has become a critical component of sugarcane breeding programs.