Radishes are a type of root vegetable in various colors and sizes, and available year round from various geographic locations. Originating in China thousands of years ago, they spread west via Egypt during the time of the pharaohs, then to Greece and Rome. Spreading to European nations much later, radishes were not found in England until 1548. Soon after, radishes were being grown in North America.
Radishes are quick-growing and generally require 4 to 10 weeks from seeding to harvest, depending on type. They are most often eaten raw in salads, but are also stir-fried, pickled, or used in soups. Most of the flavoring is found in the skin, and is diminished when peeled.
References: North Carolina State University, University of California, USDA.
TYPES, VARIETIES & CUTS
Multiple types and varieties exist, with some of the more popular being red or red and white. Varieties include Cherry Belle, Early Scarlet Globe, Red Globe, Champion, Red Prince, Sparkler, Daikon, Black, White Icicle, and California Mammoth White.
White Icicle, a winter variety, is a popular long-rooted radish with white flesh. It can grow up to 6 inches in length but requires a longer growing time than spring varieties. The Daikon radish is commonly pickled or stir-fried and can be up to 18 inches long. California Mammoth Whites are larger than White Icicle radishes with oblong roots up to about 8 inches long. Red Globe is popular in the United States and is likely the most familiar red and white radish. Black radishes have a black or dark brown skin with white flesh when peeled, and generally have a longer shelf life.
References: Cornell University, Michigan State University, North Carolina State University, University of California, USDA.
PESTS & DISEASE
Bacterial black spot is a common disorder in some production locations and will develop in postharvest storage at warmer temperatures. Prompt cooling, chlorination, and refrigeration are effective in controlling the disease. Black root is a common disease where infected mature roots are misshapen and turn black during high soil temperatures. The primary control method is genetic resistance.
Root scurf/wire stem occurs when seedlings are attacked by the fungus but survive. When the fungus attacks mature radishes, it is called scurf; symptoms are similar to black root. Seed treatment will help reduce infection, and some cultivars have genetic resistance. Downy mildew usually occurs during cool, damp weather in the fall causing yellow spots on the upper surfaces of leaves, and a white, cottony growth on the undersides.
Cabbage maggots are a serious pest, with eggs laid in the soil. Emerging maggots burrow into the plant roots. Flea beetles are tiny black insects that chew small holes in leaves, often rendering them unsuitable for marketing.
References: Clemson University, Michigan State University, University of California.