High quality blackberries are free of injury, decay, caps, and sunscald; are fully black in color; appear and feel turgid; and are of regular shape. For the fresh market, blackberry maturity can be determined by fruit color, gloss, and ease of detachment. Fully ripe black berries should pull easily from the pedicel yet be firm, not mushy. Blackberries lose acidity with ripening and are quite astringent if harvested with partial color.
TYPES, VARIETIES & CUTS
Major commercial blackberry varieties for the U.S. fresh market include Apache, Chester, Natchez, Navaho, Osage, Ouachita, Prime-Ark® 45, and Triple Crown, but there are many other proprietary varieties. Tupy is the most common variety grown in Mexico for winter export, while Marion and Columbia Star are common in the Pacific Northwest (though most Pacific Northwest berries go for processing and Marion is too soft for fresh market).
Varieties are classified as either floricane (summer-bearing) or primocane (fall-bearing), though newer primocane varieties can produce summer crops, fall crops, or both. Use of thornless cultivars is especially desired for fresh market because of the widespread use of hand labor for harvest.
PESTS & DISEASE
Gray mold rot may be seen in the marketplace during seasons when weather has been particularly wet, and begins in the growing area. Improper handling and temperature may cause the disease to rapidly spread during transit and storage. Prompt precooling of both product and transportation container and properly maintained temperatures during shipment will help control the disease.
Blackberry fruit are prone to several physiological problems that affect appearance. White drupelet is a problem with certain varieties and under certain conditions, though the exact cause is not known. While it causes some of the drupelets to be tan or white, it does not affect the flavor or healthfulness of the berries. Red cell disorder or “color reversion” occurs when berries are in refrigerated storage—fully ripe black drupelets, either on part of the berry or for the whole fruit, “revert” to the reddish color they had before ripening. Although color reversion does not affect flavor or shelf life, it can cause load rejection.
The disorder may have multiple causes (including variety, combined with cooling and handling problems) and often appears on top flats following forced-air cooling or in colder areas of trucks, indicating a freeze-type of injury. Occasionally, warm temperatures during harvest can contribute to the disorder, probably from bruising followed by leakage of small amounts of juice.
A particularly potent and more recent problem is spotted wing drosophila, or SWD, an invasive fruit fly that can lay its eggs in ripening berries. If the pest is not well-controlled in the field, small whitish larvae may be found, along with damaged or sunken drupelets and increased incidence of rot.
Redberry mites can cause part of the ripe berry to stay a bright red while the other drupelets develop to their normal black color.