ByErnie Rezents ISA Certified Arborist,
and ASCA Registered Consulting Arborist
Citrus belong to the Rutaceae family along with non-citrus white sapote, mock orange, wampi, kumquat and a few other trees of lesser importance. The genus Citrus includes the pummelo (jabon), grapefruit, orange, citron, lemon, lime, calamondin, mandarin (tangerine), and such hybrids as tangelo (tangerine x grapefruit). The limequat is a cross between a citrus, lime, and a non-citrus, kumquat.
Citrus trees are an excellent investment for any yard because of its payoff in fruit. Because of the high price of real estate and the tendency to build large houses, yard space for planting trees is limited. Most people want at least one bearing citrus tree in their yard because it fulfills the agrarian nature in all of us — food gatherers. Picking fruit from a tree planted and cared for by the homeowner fulfills, in a small way, the desire to “live off the land”.
One of the most often planted citrus is the orange, Citrus sinensis. The most popular is the Washington navel orange. The origin of this fruit is Brazil. Apparently an orange tree mutated and bore fruit without seeds. Buds were grafted onto root stock plants and two were sent to Washington DC. From those two trees all Washington navel oranges were derived. Robertson navel orange is also an excellent fruit. Both of my matured trees are about 8 feet tall by 8 feet wide. They are heavy bearers of excellent fruit. Typically the fruit have a navel, or piko, on the distal end. Typically we peel and cut up the fruit into sections for morning fruit. You can also cut the fruit into sections to eat it right off the skin. Oranges also make good juice when squeezed, and provide lots of pulp.
The second most often planted citrus is the tangerine, Citrus reticulata. The tree size varies, but is usually larger than that of a navel orange. Scientific name wise, the tangerine and Mandarin are the same. However, in the trade the name tangerine is usually applied to those with a red-orange skin. These are several popular types of tangerines: Clementine (Algerian tangerine), dancy, Okinawa, and ponkan (Chinese honey orange). Satsuma is a Mandarin. The dancy is the most popular and it can grow to 15 feet tall by 12 feet wide. Its fruit are a beautiful orange color and peels easily. Some years the fruit are sweet and juicy, while some years the fruit are juicy at first than dry later. The Okinawa tangerine is large, juicy, seedy, easy to peel, and has a lot of air space between the flesh and rind. Not a good choice. I tasted ponkan just once (grown in Pukalani) and it was excellent. Providing water periodically, especially during the dry summer, and fertilizing when the tree is developing its fruit, will improve fruit quality.
A lemon, Citrus limon, or a lime, Citrus aurantifolia, is the third most often planted citrus. The popular Meyer lemon is a hybrid between possibly a lemon and a mandarin. It was introduced into the US in 1908 by the explorer, Frank N Meyer, who found it growing as an ornamental pot plant near Peking, China. It is a small tree (about 8 feet tall and wide) and a heavy producer of fruit the size of tennis balls. It is so productive that it will produce fruit the first year it is planted in the ground. Pick these fruit when tiny to direct the tree’s energy into developing roots, branches, and leaves instead. If you like an acid lemon, grow the Eureka lemon. This is the number one commercial lemon from the mainland and is the type you usually buy in the store. Some folks like the rough bumpy skin lemon, erroneously called the “Hawaiian lemon”. It is perhaps a hybrid of a lemon and citron. It has the botanical name of Citrus jambhiri. This was the main type of lemon we had in Hawaii for many years; probably due to the multitude of seeds it produces that germinate very easily. The tree typically has long thorns, and for many years was used as root stock for grafting citrus. It is no longer used as a root stock because it is not resistant to many citrus diseases.
Limes are also a good choice to grow. One of the best is Bearss seedless lime or Tahitian lime. This is a slightly larger tree — 10 feet tall by about 8 feet wide. The fruit is easily recognized by its green skin that turns yellow when ripe, and a small nipple at its tip. The pulp is slightly greenish yellow when ripe. Another lime is the Mexican lime. This tree ranges in size from 6 to 10 feet tall with a spread of about 8 feet.
If making juice or eating off a quartered fruit is your goal, you just cannot beat the Minneola tangelo. As said earlier, it is a hybrid between a tangerine and a grapefruit. There are several different cultivars but the Minneola is the only type I plant. It turns a beautiful orange color when ripe, has a pronounced neck, and is so full of juice that it weeps when cut. It juices easily because its segments are not tough as is that of the orange.
There are several citrus diseases. The most serious is Tristeza, “the aids of citrus” because it is due to a virus and has no cure. It is spread from a sick tree to a healthy tree by the black citrus aphid. The aphids are typically found in the spring and fall of each year. It is difficult to find a matured tree in Hawaii without the disease. When you see peeling bark and resin on branches, this is a sign of tree stress due to disease or drought. When the tree dies one large branch at a time, you probably have Tristeza. Some trees die quickly and others live for many year. Death is inevitable. The sick tree becomes a source of virus to contaminate other trees. You can continue to enjoy the fruit, or cut it down. Replace it with another young tree.
Planting only grafted trees provides you with a root stock resistant to Tristeza. The fruit bearing part may have the disease, but the root stock is resistant so it continues to absorb water and minerals to prolong the life of the tree. Air layered trees do not have the resistant root stock so the disease travels throughout the entire tree. Death may be faster. Sterilize your pruning tools between trees with a spray of straight rubbing alcohol. Heat from a propane torch is also effective.
My yard grows many other types of citrus and citrus relatives. Space here limits coverage. Reading the Maui News Successful Island Gardening
articles in June 12, June 26, July 10, and July 24, 1994 will provide you with much information.Successful Gardening to You.
articles in June 12, June 26, July 10, and July 24, 1994 will provide you with much information.Successful Gardening to You.