Thiourea, a New Thinning Agent for Early-ripening Peaches and Nectarines1

Thiourea will thin ‘Sunred’ nectarine and early peach cultivar flower buds effectively when sprayed at a concentration of 2 to 3% at the beginning of bud swell. Flower-bud thinning was not accompanied by any significant phytotoxicity at this period. Earlier and later application resulted in a reduced thinning effectivity with the latter also causing damage to leaf buds and young shoots. Fruit on chemically thinned trees were larger and matured earlier than those on hand-thinned trees.