Effect of fenarimol application timing on fruit shape of Bartlett pear

Plots were established at Ukiah and Davis, California, and Medford and Hood River, Oregon, to evaluate the effect of fenarimol (Rubigan 1 EC), applied at various stages of bloom development, on fruit shape of Bartlett pear. A t each location, 10 different treatment schedules were applied at various c ombinations of bud burst (BB), green cluster (GC), white bud (WB), and full bloom (FB). In schedules that included an application at FB, the fruit len gth:diameter (LCD) ratio was significantly reduced in at least three of fou r locations when compared to untreated controls. When fenarimol was applied at BE, GC, WE, and FB, the LID ratio was reduced at all locations. Treatme nt at BE only did not affect L/D ratio. Schedules involving GC or WE, but n ot FB, resulted in reduced L/D ratios at only one or two locations. When da ta from all four locations were combined, L/D ratios were significantly red uced by all fenarimol treatments except BE alone, and the smallest L/D rati os resulted from treatments which included applications at both WE and FB. Fruit stem length was significantly reduced by all timings of fenarimol app lication except GC at Medford, and all timings except BE and GC at Ukiah. F ruit weight did not differ among treatments.