Variation among sugarcane clones for resistance to armyworms

Ratings of leaf damage by armyworms in sugarcane ratooning under conserved trash showed significant differences among 115 clones in four field trials in southern Queensland, Australia. Damage to current commercial cultivars v aried significantly with Q170 the most susceptible and Q151 the most resist ant. There were no significant effects of past levels of nitrogenous fertil iser or of past irrigation regimens. Good repeatability between trials and heritability of up to 0.90 indicated that selection of clones for resistanc e to armyworms is feasible. The simple nature of the rating system also mak es selection practicable. The nature of the resistance is not known, but re sponses are consistent with the effects of artificial shoot removal. Becaus e ratooning vigour is a significant covariate in the analysis of damage rat ings, variation in tolerance may be an important component. (C) 2000 Elsevi er Science B.V. All rights reserved.