Plums & Pluots
Plums and pluots are stone fruits with smooth skin and small pits. Plums are native to Asia, Europe, and America, and most U.S. production uses Japanese varieties, which range in color from yellow, red, and blue to almost black. European varieties are blue and purple.
Pluots are a combination of apricot and plum, one of many ‘interspecific’ hybrids called plumcots, apriums, and apriplums. The pluot name is trademarked, so growers cannot legally call their fruit pluots.
While pluots and plumcots have occurred naturally in regions where apricots and plums grow freely, modern versions have been cross-pollinated for maximum flavor and shelf life. Today’s pluots are usually one quarter apricot and three-quarters plum, with smooth skin in various colors and flavors.
Plums and pluots are related to cherries and members of the rose family. Prunes are dried plums, typically the European type.
Types & Varieties
European, Damson, and Japanese are the most common types of plums: European plums are often used for canning, but are eaten fresh as well.
Damson are very tart and primarily for cooking and preserves; Japanese are the most common fresh market plums.
Pluots have smooth skin, can be solid or speckled and yellowish green to black. Pluot flesh is white to red and fruit is usually larger than plums and higher in sugar content.
With a short supply window for most apricot-plum hybrids, varieties have increased to maintain availability. Pluot varieties include Cherry, Crimson Sweet, Dapple Dandy, Geo Pride, Flavor Heart, Golden Treat, Jubilee, Red Ray, Raspberry Jewel, Sugar Baby, and Supernova.
Some plum cultivars can self-pollinate; most require cross-pollination. Trees favor fertile, well-drained soil and bear fruit in 3 to 5 years, with full production in 10 years. Pluot trees begin bearing in 2 to 3 years. Average lifespan is 15 to 20 years.
Plums are ready for harvest when flesh is firm. Pluots should be plump and firm at harvest, not green.
Pests & Diseases
Oriental fruit moths and oblique banded leafrollers are regional concerns. Both katydids and light brown apple moths affect the surface of fruit, while mites and mealy plum aphids curl leaves and stunt growth. American plum borer larvae dig into bark, damaging younger trees, though more vigorous trees will heal.
Brown rot begins during flowering and fruit rot occurs postharvest in warm temperatures. Grey mold can be a threat to fruit with wounds.
For pluots, bacterial canker survives in or on plant surfaces and like crown gall is hazardous to young trees. Powdery mildew attacks fruit and/or foliage.
Storage & Packaging
Plums can be stored at 32°F with a 90 to 95% relative humidity for 2 to 4 weeks; pluots favor warmer temps of 32 to 36°F, the same humidity, and will last up to 3 weeks. Both fruits produce ethylene.
References: Michigan State University Extension, Ohio State University Extension, UC Davis Postharvest Technology Center, South Australian Research and Development Institute.
GRADES & GOOD ARRIVAL
Generally speaking, the percentage of defects shown on a timely government inspection certificate should not exceed the percentage of allowable defects, provided: (1) transportation conditions were normal; (2) the USDA or CFIA inspection was timely; and (3) the entire lot was inspected.
|U.S. Grade Standards||Days Since Shipment||% of Defects Allowed||Optimum Transit Temp. (F)|
Canadian good arrival guidelines (unless otherwise noted) are broken down into five parts as follows: maximum percentage of defects, maximum percentage of permanent defects, maximum percentage for any single permanent defect, maximum percentage for any single condition defect, and maximum for decay. Canadian destination guidelines are 15-10-5-10-3.
References: DRC, PACA, USDA.