Growth Index and Disease Ratings of 55 Crape Myrtle Cultivars in Tennessee

Abstract

Fifty-five accessions of commercially available crape myrtle cultivars were established with 10 single-plant replications during Fall 1993 and Spring 1994. Drip irrigation began on a regular basis May 1994 and plants were fertilized regularly. In contrast to the 1994 growing season with heavy powdery mildew infestation, little powdery mildew occurred in 1995. Mean growth index (GI = centimeter height + centimeter mean width) was calculated for each cultivar in Fall 1994 and 1995. Fastest growth occurred in `Tuskegee' and `Biloxi' (GI = 276, 246, respectively), followed by a group including `Tonto', `Comanche', `Choctaw', `Hardy Lavender', `Natchez', `Potomac', and `Tuscarora' (GI = 185 to 227). Slowest growth occurred in the group including `Pecos', `Seminole', `Baton Rouge', `Petite Orchid', `Bourbon Street', `Cherokee', `Monink Pink', `Moned Red', `Delta Blush', `Low Flame', `New Orleans', `Monow', and `World's Fair' (GI = 5 to 53). Data will be presented on powdery mildew ratings and physiological injury sustained during Winter 1995–96.