Plant Disease (2009) 93, 1335-1340

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Sushma G. Sood, Jack C. Comstock and Neil C. Glynn (2009)
Leaf whorl inoculation method for screening sugarcane rust resistance
Plant Disease 93 (12), 1335-1340
Abstract: Brown rust, caused by Puccinia melanocephala, and orange rust, caused by P. kuehnii, are agronomically important diseases of sugarcane in Florida. Cultivar resistance is the best means of controlling these diseases. Natural infection has been the primary means of assessing resistance in sugarcane cultivars against rusts; unfortunately, natural infection is not always efficient in identifying resistant cultivars due to variable environmental conditions. Therefore, a more reliable screening method is needed to effectively select resistant genotypes. An inoculation technique was evaluated for identification of brown and orange rust resistance in sugarcane cultivars. Inoculations were performed in the field by placing a 0.5-ml urediniospore suspension in the leaf whorl of three individual sugarcane stalks per plant using a pipette. Symptoms developed on leaves of all the susceptible cultivars after 4 weeks, and appeared as a band of pustules. Plants were rated for their reaction to rust 4 weeks after inoculation. The optimum concentrations of inoculum for expression of brown and orange rust symptoms were determined. The most severe brown rust and orange rust symptoms were observed using inoculum containing 105 and 104 urediniospores/ml, respectively. Clones in several stages of the Canal Point breeding program were screened for their rust reaction by leaf whorl inoculation. The technique enabled rapid screening of a large number of cultivars in field plantings using a small amount of inoculum and limited man hours.
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Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Puccinia melanocephala Sugarcane (Saccharum officinarum) U.S.A. (SE)
Puccinia kuehnii Sugarcane (Saccharum officinarum) U.S.A. (SE)