MITIGATION EFFECTS OF CYTOKININ PLANT-GROWTH REGULATOR ON TURFGRASS ROOT-BIOMASS LOSS BY WHITE GRUBS

Damage to the turfgrass root system caused by white grubs was compared in the presence and absence of two commercial formulations of natural cytokinin hormone biostimulants. Cytokinin + nitrogen + iron (CytoFe( R)) was the most effective treatment in stimulating root-biomass produ ction; 18% and 42.8% more root biomass was produced in the presence an d absence, respectively, of a high density of white grubs compared wit h untreated turfgrass. CytoFe(R), if applied more than 4 times, was no t cost effective compared with one insecticide application. Cytokinin (CytoGro(R)) alone did not entirely compensate white grub damage; 6.2% and -7.6% in the absence and presence of white grubs compared with un treated turfgrass, but it was cost effective even with six application s. Neither cytokinin treatments significantly reduced average weight o r numbers of white grubs. These findings present an alternative treatm ent for white grub control and the possibility of including the use of this hormone product in an integrated management program.