Chemical Treatments to Delay Bloom in Peach

Abstract

Abstract CGA-15281 applied in the fall delayed bloom in peach (Prunus persica L. Batsch) by 4–9 days without damage to the trees. The length of the delay was cultivar and concentration dependent. Fall ethephon applications (500 ppm) damaged trees severely, but delayed bloom 10–18 days, whereas 125 or 250 ppm ethephon caused little tree damage and delayed bloom 3–5 days. Bloom delay from application of ethylene-generating compounds resulted from both prolonging rest and slow bud development once rest was complete. Daminozide applied in January caused bloom delay in 1983 but not in 1984. Silver nitrate had little effect on bloom delay or blossom density at any time of application. Dimethipin and merphos applications in late summer caused defoliation and reduced blossom density, but did not affect date of bloom. Thidiazuron did not induce defoliation or delay in bloom, but greatly reduced blossom density. Chemical names used: (2-chloroethyl)methylbis(phenylmethoxy)silane (CGA-15281); (2-chloroethyl) phosphonic acid (ethephon); butanedioic acid mono (2,2-dimethylhydrazide (daminozide); 2,3-dihydro-5,6-dimethyl-1,4-dithiin 1,1,4,4-tetraoxide (dimethipin); N-phenyl-N′-1,2,3-thiadiazol-5-ylurea (thidiazuron); Tributyl phosphorotrithioite (merphos).