PENETRATION OF IPRODIONE INTO MESOCARP FRUIT TISSUE AND SUPPRESSION OF GRAY MOLD AND BROWN-ROT OF SWEET CHERRIES

The efficacy of iprodione in controlling postharvest decay of sweet cherries (Prunus avium) caused by Botrytis cinerea and Monilinia fructicola was related to penetration of the fungicide into the mesocarp tissue of the fruit. In laboratory studies, fruit sprayed with an aqueous suspension of iprodione at 600 or 1,200 mug a.i./ml (Rovral 50 WP) 1 hr before inoculation or 24 hr after inoculation (20 mul of 25,000 conidia per milliliter), prevented decay or completely suppressed development of decay caused by B. cinerea or M. fructicola. Additionally, penetration of iprodione was shown when fruit surfaces were sprayed with iprodione at 1,200 mug a.i./ml and inoculated at the pit using a syringe containing a conidial suspension of B. cinerea or M. fructicola. Fruit treated with iprodione had significantly less internal decay at the pit caused by either fungus than did fruit sprayed with water. Furthermore, decay was inhibited near the epicarp in treated fruit but not in nontreated fruit. Diameter of internal lesions at the pit caused by B. cinerea decreased linearly with increasing concentration of iprodione. Residues of iprodione in mesocarp tissue of fruit surface-sprayed with iprodione at 1,200 mug a.i./ml ranged from 0.18 to 0.21 mug/g of tissue.