An Improved Procedure for the Quantitative Estimation of the Rust Fungus in Infected Plant Tissue

A quantitative estimation of the rust fungus in infected wheat leaves was possible following enzymatic hydrolysis of the chitin and colorimetric determination of the N-acetylglucosamine released. The apparently complex cell wall structure of the fungal structures made it necessary, how­ ever, to use an enzyme mixture of chitinase and cellulase in order to make accessible the chitin of the cell wall for diges­ tion by chitinase. In applying this method the measurement is not appreciably influenced by already formed urediospores as would otherwise be the case were the chitin to be determined on the basis of glucosamine after chemical hydrolysis.