Botanically watermelon is a warm-season fruit, though as a member of the cucurbit family of gourds, it is grown and harvested as a vegetable. Most believe watermelon originated in the deserts and semitropical regions of southern Africa. Hieroglyphics found on the walls of ancient Egyptian buildings depict the first watermelon harvest occurring nearly 5,000 years ago. Today, watermelon is grown around the world and its composition is up to 95% water, hence its name. Rinds, whether solid in color or striped, look hardy but are quite fragile and require picking by hand at harvest. Interestingly, watermelon is completely edible: the flesh is sweet and juicy, the seeds can be roasted, and the rind can be used for making preserves, pickles, and relish.
References: National Watermelon Promotion Board, North Carolina State University, University of Georgia Cooperative Extension, USDA.
TYPES, VARIETIES & CUTS
There are several hundred varieties of watermelon grown in the United States and Mexico. The five most common types are Seeded, Seedless, Mini, Yellow, and Orange, with many popular cultivars within each category. Rind and flesh colors can vary, as well as both size and shape.
Top growing regions in the United States are Florida, Georgia, California, and Texas. Prevalent seeded varieties grown in these states and elsewhere include Calsweet, Fiesta, Royal Sweet, Sangria, Sultan, and Tiger. Seedless varieties, which continue to gain in popularity, include Cotton Candy, Crimson Trio, Fandango, Fire Cracker, Genesis, King of Hearts, Nova, Scarlet Trio, Super Cool, Summersweet, Supersweet, Sweet Slice, and Tycoon.
Mickeylee, Palm Melon, Precious Perfection, Precious Petite, Solitaire, and Sugar Baby are popular miniature watermelon varieties. Crimson Sweet and Charleston Grey varieties produce larger, more traditional melons in both Florida and Georgia, along with Florida Giant and Sweet Favorite in Georgia.
Lesser known though gaining converts are yellow-fleshed varieties, which include the aptly-named Summer Gold, Yellow Baby, and Yellow Doll. Gold Strike is an orange-fleshed variety.
References: National Watermelon Promotion Board, Texas A&M AgriLife Extension Service, University of California Vegetable Research & Information Center, University of Florida/IFAS Extension, University of Georgia Cooperative Extension, USDA.
PESTS & DISEASE
Cucumber beetles attack plants, feeding on leaves and stems, but should not be confused with lady beetles, a beneficial insect. Both striped and spotted beetles can cause damage; striped cucumber beetles can transmit diseases like bacterial wilt. The best way to prevent these pests is removing weeds or planting a “trap crop” to attract the insects away from melon plants.
Aphids cause leaves to curl and can prevent plants from growing to full size. Melon aphids, specifically, can be identified by their long legs, antennae, and range of color from yellowish-green to greenish-black. Aphid ‘honeydew’ secretions can cause fungal growth on plants and attract other insects like ants. If aphid colonies and damage are detected early, they can be controlled with insecticide sprays or soaps, summer oils, or fatty acid salts. Alternatively, introducing natural aphid enemies—such as parasitic wasps or lady beetles—can help lower populations.
Rindworms include several caterpillar species such as beet armyworm, cabbage lopper, cutworms, and tobacco budworms. Typically green and striped, rindworms feed on stems and foliage but the more costly damage is feeding on rinds. Often light in color, damage is difficult to spot.
Other insect dangers include leafminers, spider mites, squash bugs, stink bugs, thrips, vine borers, and whiteflies.
Anthracnose, a fungal disease, is recognized by small, brown-black spots on leaves and fruit. On watermelon, these spots may begin as quarter- or half-inch circles. Prevention methods include seed treatment, crop rotation, and fungicide applications; protective sprays can be used if the disease is spotted early.
Downy mildew is caused by an airborne fungus and exacerbated by heavy rains. Yellow-brown spots appear on the leaf surfaces with a brown to grey fungus on the underside.
Fusarium wilt can survive for years in sandy soils, like root-knot nematodes. As the name implies, it can be identified by wilting leaves during the day as well as a yellow color on the underside of the leaflets that will eventually spread to the rest of the plant. While there is no proven fungicide to counteract the wilt, methods for controlling the disease include crop rotation, avoiding excessive use of nitrogen, and eliminating debris (which can spread the disease).
Other diseases include gummy stem blight, bacterial fruit blotch, rind necrosis, and watermelon mosaic virus.
References: North Carolina State University Cooperative Extension, Purdue University, Texas A&M AgriLife Extension, University of California Agriculture and Natural Resources, University of Florida/IFAS Extension, University of Georgia Cooperative Extension, University of Illinois Extension.