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United States Department of Agriculture

Agricultural Research Service

Title: Screening Program to Develop Disease Resistant Cultivars at Canal Point, Florida

item Comstock, Jack

Submitted to: Acarology International Congress Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/18/2012
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Every Cultivar Development Program must address local diseases to be successful. The Canal Point Program in Florida has five Stages and one phase: Seedling Stage (70,000 plus seedlings), Stage I (15,000 clones), Stage II (1,500 clones), Stage III (135 clones at 4 locations; 3 organic and one sand), Stage III Increase phase (40 clones at 11 locations; on either organic or sand) and Stage IV (13 clones at the same 11 locations). Disease clones from natural infection are discarded in the first 3 Stages. Clones in Stage II are screened for their reaction to eye spot pathogen; in addition clones in Stage II and Stage III are also screened for ratoon stunt, brown rust and orange rust resistance. Clones in Stage III Increase phase and Stage IV are screened for their reactions to pathogens of brown rust, orange rust, leaf scald, mosaic, smut and ratoon stunt. When and how disease screening occurs in the five stages of the program depends on the following factors: 1. The ease of screening. 2. Economic importance of the disease. 3. The incidence of resistance present. 4. The amount of seedcane and land required. 5. Reliability or repeatability of the assay. Since the introduction of orange rust to Florida in 2007, it has been evaluated in all stages of the program based on natural infection and in specialized screenings because of its economic importance impact and the need to eliminate susceptible clones. Brown rust is also evaluated in all stages, but the earlier stages are emphasized using both natural infection and whorl inoculation techniques. Because large amounts of seedcane are required for evaluating the reactions of clones to smut, leaf scald and mosaic pathogens, the screening of these diseases starts using artificial inoculation in the Stage III increase phase when the number of clones has been reduced to 40. Fortunately, the level of susceptibility is low for these diseases. Clones are screened for ratoon stunt resistance in stage II (1,500 clones) and is continued at all subsequent stages because the inoculation method is easy and to eliminate the low level of inoculation escapes. The screening program is continually being adjusted for improved methodology and for the emerging diseases.

Last Modified: 06/26/2017
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