Ratios of Reproductive to Vegetative Growth in Six Blackberry Cultivars

Blackberry fruit is gaining popularity in the U.S. and overseas.  New cultivars have been developed in recent years that provide more options for growers and homeowners alike.  Although proven in major blackberry growing regions around the world, these cultivars have not been tested extensively in potential emerging areas.  In Oklahoma, some growers noticed that canes were dying with ripening fruit still attached.  The fruit would not reach maturity and thus be unharvestable.  One potential cause is an unbalanced leaf-to-fruit ratio.  In this study, six blackberry cultivars were used to assess the reproductive and vegetative growth ratios.  Three plots with three canes per plot were individually harvested, had leaf counts, and leaf area measurements.  Leaves were counted on canes in mid-June, during harvest, and mid-July, immediately after the final harvest.  ‘Apache’ had the greatest number of leaves per berry in June (2.6) and July (2.0).  In June, all other cultivars (Chickasaw, Natchez, Ouachita, Triple Crown, and Tupi) were not significantly different from each other, but ranged from 1.4 to 1.1 leaves per berry.  In July, ‘Chickasaw’ was significantly different, having only 0.6 leaves per berry. ‘Natchez’ produced the most berries and the most leaves. These data may help give insight into the phenomenon of premature cane death.