Avocado: perfect for Hawaii
While the Kona district is traditionally known as the best avocado growing area in the state, well-selected avocados will grow and fruit from sea level to about 2,000 feet elevation statewide. Kona is reputed to be the best avocado growing region because many of our cultivars originated from seeds that were planted in area coffee fields from which the best were selected and propagated based on their fruit quality. Many cultivars bear the surname of the farmer on whose farm the original tree grew.
Avocados are harvested in Hawaii year-round. Many of us have trees growing in our yards or know friends or relatives who are willing to share their bountiful crop. Avocado is easy to grow and by planting several selected cultivars that mature at different times, your harvest can be nearly year-round.
A 1 cup serving of cubed avocado is about 240 calories because of its high fat content. However, most of that fat is the healthy monounsaturated variety. Avocados contain more than 20 vitamins and minerals considered necessary for good health and are a good source of dietary fiber, potassium — higher than bananas — and folic acid. Eating avocado is also believed to be a natural way to eliminate bad breath.
Avocado, Persea americana, originated in tropical America. Three races are recognized that reflect the harvest season, fruit and plant characteristics and adaptation to specific environmental niches.
The Mexican race is native to the highlands of Mexico and has anise-scented leaves, 8-ounce fruits with smooth, thin skins that ripen in six to eight months. It is the most cold hardy. Its oil content approaches 30 percent. Seeds are loose and tend to rattle within the fruit when shaken.
The Guatemalan race is native to the highlands of Central America and has large 1- to 2-pound fruits that ripen within nine to 12 months and contain 8 to 15 percent oil. Fruits hang from long stems, and skins are thick, bumpy, hard and brittle, which contribute to the grittiness around the cut surface when eaten. Seeds are normally small and tightly held in the fruit.
The West Indian race originated in the lowlands of Central America. It has fruit smaller than the Guatemalan race and matures between six and nine months. Fruits hang on short stalks, have smooth, leathery skins and the seeds are large and generally loose within the fruit. With oil content ranging from 3 to 10 percent, it lacks the smooth buttery texture of the other races.
You may wonder why none of these descriptions sound like fruit you’ve recently eaten. The reason is that many of Hawaii’s avocado varieties are hybrids of the different races. For the avocado, crosspollination or hybridization is a natural process and a reason why it is not recommended to plant a single avocado tree in your yard, especially if you don’t have neighbors with trees. It is also the reason you should purchase a grafted tree instead of planting a seed from a good avocado you just ate.
All avocados generally flower during the same period and the number of months to maturity account for differing harvest dates. Pollination biology in avocados is classified as synchronous dichogamy in which two types of flower opening, known as types A and B, are present. For type A avocados, female organs are functional in the morning of the first day and on the afternoon of the second day the male organs become functional. In type B avocados, the female organs are functional in the afternoon of the first day and the male organs are functional in the morning of the second day. Therefore, to maximize fruit number, it is best to plant both types. However, there is some overlap of morning and afternoon functions and some self-pollination does occur. Some of the better known type A cultivars are Greengold, Hass, Ohata and San Miguel. The better known B cultivars are Kahaluu, Malama, Murashige, Nishikawa and Sharwil.
For more information on this and other gardening topics, visit the University of Hawaii College of Tropical Agriculture and Human Resources’ electronic publication website at ctahr.hawaii.edu/Site/Info.aspx or visit any of the local Cooperative Extension Service offices around the island.
Russell Nagata is the Hawaii County administrator of the University of Hawaii at Manoa College of Tropical Agriculture and Human Resources. He can be reached at email@example.com.