Charles A. Mullins

‘Boston’, ‘Triple Crown’, and ‘BSI 9330' were the most acceptable seedless cultivars. ‘Summer Flavor 800’, ‘Mardi Gras', and ‘Carvinal' were among the most promising seedy type cultivars.

Watermelons are not grown extensively in Tennessee. Production for shipping and local markets appears to have potential for expansion, especially for seedless cultivars. Producing melons of a consistent size may be a problem. Weed control can be a problem, but new herbicides may be labeled in the near future. An experiment was conducted at the Plateau Tennessee Experiment Station at Crossville, TN in 2000 to evaluate performance of 36 watermelon cultivars. Twelve of the cultivars were seedy, and 24 were seedless. One cultivar was yellow fleshed, and the others were red fleshed.

The site was prepared for planting using conventional tillage in late April. Fertilizer was broadcast at 400 lb/A of 15-15-15 before final disking on May 22. Bensulide (Prefar) at 6.0 lb ai/A was soil incorporated for weed control on May 22. Four ft wide black plastic mulch was laid on 12 ft centers on May 22. Transplants of the selected cultivars were greenhouse grown in 4 inch peat pots. Four seeds were planted per pot and the stand was thinned to 2 hills per pot before transplanting on May 22. Plots consisted of one row with 5 hills spaced 4 ft apart in rows spaced 12 ft apart. The cultivars were not replicated. Row middles were cultivated on June 22. Fungicides included azoxystrobin (Quadris) at 0.2 lb ai/A or chlorothalonil (Bravo) at 1.6 lb ai/A and were applied on 7 to 14 day schedule. Esfenvalerate (Asana) at 0.05 lb ai/A was applied with each fungicide application. Harvest of all cultivars was on August 23 and 24.

Melon counts and individual melon weight per plot were recorded. Melons were classed according to size class of melons. Size classes were less than 15 lb, 15 to 20 lb, and over 20 lb. The total melon number and average melon weight were calculated for each plot according to size classification.

The seedless cultivars produced a large percentage of melons that averaged between 9 and 11 pounds per melon (Table 1). ‘Millionaire’, ‘Boston’, ‘Triple Crown’, and ‘BSI 9330' were among the most productive seedless cultivars in number of melons per plot that weighed between 15 an 20 pounds per melon. ‘Millionaire' and ‘Sterling ' had the largest number of seedless melons that weighed over 20 pounds per melon.

‘Revolution', ‘Sterling’, and ‘SWT 6903' produced the longest melons of the seedless cultivars (Table 2). Melons of ‘Solid Gold’ and ‘SWT 6903’were slightly larger in diameter than melons of the other cultivars. Most seedless melons were almost round. Melons of ‘Boston’, ‘Revolution’, ‘Triple Prize’, ‘Tri-X-313', ‘’BSI 9330' and ‘Fandango’ had the darkest flesh color. ‘Solid Gold’ was rated low in flesh color as it has yellow flesh. ‘Boston’ and ‘Triple Star’ were rated highest for flavor. ‘SWT 6903' had the highest fruit soluble solids. Most cultivars had a light green external color with darker green stripes. ‘Millennium’ was dark green without stripes with the appearance of an icebox or ‘Sugar Baby’ type melon.

‘Summer Flavor 900' and ‘Summer Flavor 800' produced the most melons of the seedy cultivars that weighed over 25 pounds (Table 3). ‘Carnival’, ‘Royal Flush’, and ‘Royal Sweet’ produced the most melons that weighed 20 to 25 pounds.

Fruit of all the seedy cultivars except ‘Crimson Sweet’ were elongated (Table 4). Fruit of ‘Summer Flavor 800', ‘Summer Flavor 900', ‘Starbrite’, and ‘Stars and Stripes’ were the most elongated. ‘Summer Flavor 800', ‘Carnival’, and ‘Royal Flush’ had the darkest red flesh color. ‘Summer Flavor 800' was rated high for flavor. Fruit of ‘Summer Flavor 900' had a low soluble solids level.

Weed control was a problem in the trials, and was probably the cause of so many small fruit. Rainfall just prior to runner development off the black plastic mulch prevented a timely cultivation for weed control.

Table 1. Yield in number and average weight by size classes of seedless watermelon cultivars evaluated at the University of Tennessee Plateau Experiment Station at Crossville, 2000.