Fragaria x ananassa, more commonly known as strawberries, are a perennial in the rose family. The strawberry has an incredible reach and can be found in native forms on every major continent excepting Africa and the Australasia continent with Australia and New Zealand. Today, strawberries are grown in all U.S. states and Canadian provinces, with California leading production most of the year, then Florida picking up domestic supply in the late fall and winter months.
The deep red fruit was once much smaller, but selective breeding and adaptation have resulted in larger, juicier berries for the fresh market. Strawberries are not, however, considered true berries since their tiny black seeds are on the outside instead of inside the fruit; for this reason, they are classified as “aggregate accessory fruits.” Although most strawberries are grown for the fresh market, they are also frozen and processed into a number of items such as jams and purees.
References: University of Illinois Extension, University of California Cooperative Extension, Washington State University.
TYPES, VARIETIES & CUTS
Strawberries are generally described as June bearing, everbearing, or day neutral. June bearing refers to the two- to three-week period the crop produces fruit in the spring. These crops typically produce berries that are larger than those from everbearing and day-neutral types and are more popular with commercial growers.
June bearing types have three different varieties: early, mid-season, and late. Everbearing types do not produce crops all season as the name implies, but rather once in spring and again toward the end of summer.
Depending on the region, however, everbearing varieties can produce three crops: one each in spring, summer, and fall. Day neutral types produce fruit all season long. All three types are highly susceptible to frost damage.
There are many varieties available for all types, which vary in sweetness, color, and fruit size. Varieties include Allstar, Annapolis, Carmine, Chandler, Earliglow, Florida Radiance, Fort Laramie, Honeoye, Jewel, Ozark Beauty, Seascape, Sparkle, Strawberry Festival, Surecrop, Tristar, and Winterstar.
References: Colorado State University, University of Florida Extension, University of Illinois Extension, University of Missouri Extension.
PESTS & DISEASE
Strawberry bud weevils, also called ‘clippers,’ can cause considerable damage. The females lay eggs once a year inside buds then ‘clip’ them to prevent flowering and exposure of the eggs.
Leafrollers generate twice per year and hide themselves in cocoon-like enclosures secured with silky, white, thread-like webbing. They feed while enfolded in the leaves and then as the plant matures, work their way to the fruit, leaving tiny holes.
Strawberry aphid waste is referred to as ‘honeydew’ and is the cause of sooty molds. The aphids shed their skin, which sticks to the mold and contaminates the fruit.
Strawberry yields can also be impacted by mites, rootworms, sap beetles, strawberry crown borers, tarnished plant bugs, thrips, and white grubs.
Botrytis rot or grey mold will grow at 32°F, albeit very slowly. Grey mold is the most common cause of postharvest fruit loss and starts as white in color, but quickly turns grey.
Rhizopus rot is easily spread through airborne spores and is characterized by black spots. Infected fruit will become soft and leak sticky red juice. The disease will not grow in temperatures below 41°F, so proper storage temperatures can prevent losses.
Mucor rot looks very similar to Rhizopus rot since the infected fruit becomes soft and leaky, yet has a hair-like appearance and row pattern. Red stele root rot is a fungal disease causing damage in wet winter and spring months. Plants will appear stunted and dull, with younger leaves displaying a blue-green pall.
Other diseases that can present challenges for strawberry cultivation are black root rot, leaf rot, fruit rot, blossom blight, powdery mildew, leaf scorch, and verticillium.
References: Agricultural Marketing Resource Center, Colorado State University Extension, Cornell Cooperative Extension, Minnesota Dept. of Agriculture, PennState Extension, UC Davis Postharvest Technology Center, University of Illinois Extension.