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  • 1 Department of Plant and Soil Science, Southern Illinois University, Carbondale, IL 62901.

Manually pinched plants of 18 cultivars of Impatiens hybrids (Keintzler New Guinea impatiens) were compared to control plants to determine the effect of apical meristem removal on flowering, growth and branching. Pinching delayed days to anthesis (first flower) of all cultivars, however, further delay in days to marketability (5 flowers open) was dependent upon cultivar. Plant area and fresh and dry weight were not affected by pinching plants of any cultivar. Cultivar influenced response to pinching treatments for plant height and plant width. Secondary branch number was increased by approximately 3 branches for all cultivars when plants were pinched. There were interactions between cultivar and treatment for primary, tertiary, and total branch number. Measured improvements in plant form determined two cultivars, Sylvine and Thecla, should be pinched. Chemically pinching these two cultivars with dikegulac at 780 mg·liter-1 was comparable to manually pinching plants.