For a fruitful tree, a little research goes a long way

A fruit tree can be the best gift. Visions of bountiful fruit and lower grocery bills fill the new owner with hope.

But I encourage caution at this stage — you may not know this living thing that you’ve adopted.

University of Hawaii Master Gardeners throughout the state are graduating from training classes and are there to help, though if they don’t know the answer, they may have to do some research and get back to you.

Here is one common, but frustrating problem: a fruit tree that has never given fruit. A master gardener will ask you many questions to get the whole picture, but here are some common causes for a non fruit-bearing fruit tree.

» Bearing age: Many fruit trees do not bear fruit until they are old enough, usually from 3 to 7 years old, depending on the type of tree. Introduced in Hawaii more than two centuries ago, citrus trees will not bear fruit until six to seven years from seed, maybe sooner if grafted.

» Pollination: Knowledge of the way fruit trees are pollinated is important. A large portion of our food depends on pollinators, which are in decline in our state. Some fruit trees are wind-pollinated, some depend on naturalized pollinators, though either way, for many trees timing of pollination is critical. Edible crop farmers and backyard gardeners must resort to hand pollination when it is not consistent.

» Weather: There are some things that we cannot control. Flowers are needed to produce fruit. Gusty wind will knock flowers off their panicles. Heavy rains can reduce pollen and therefore reduce pollination, resulting in lack of fruit production.

» Health: Amending soil properly at planting (mixing a fine compost and or animal manure with your existing soil), pruning properly (to allow new growth and maintain old growth), watering properly (aim for consistency, paying attention to seasonal changes in precipitation), maintaining a pest control and fertilizer routine (taking a soil sample and monitoring for nutrient deficiencies and toxicities, avoiding over fertilization), and applying a fresh layer of compost on root systems will ensure your fruit tree is at optimum health. The healthier the fruit tree, the more it will be able to fight off insects, disease and viral attacks. Read the UH College of Tropical Agriculture and Human Resources publication (www.ctahr.hawaii.edu) associated with your fruit tree and use it like a check list. These publications won’t include your tutu’s tricks for optimum fruit production, but they all contain the baseline information important for good health.

» Insects: Just as we are lucky to live Hawaii, so are our plant insects, diseases and viruses. Once introduced, they live a long, tropical lifestyle, enjoying year-round feeding and breeding. Insect damage can cause stress to the tree. Plant stress can result in reduced flowering and fruit.

» Life expectancy: Plants don’t live forever. Fruit tree life spans can range from 30 to 70 years in the tropics. As the tree approaches the end of its life, it will decline in fruit.

» Home gardener knowledge: Being honest about what you know and don’t know will take you far in your backyard. Learn as much as you can about your plant. Important issues include location of planting, sunlight exposure, choice of variety in relation to local conditions, available space and access to water.

As I talk to home gardeners, I remind them that the tropical conditions in Hawaii are harsh for plants. In many other places, trees get a winter break. In Hawaii, they are expected to grow all year and produce fruit. We should at least be good hosts and learn about what they need.

Jayme Grzebik is an urban horticulturist for the UH CTAHR Cooperative Extension Service and statewide coordinator of the UH Master Gardener Program. She can be reached at grzebik@hawaii.edu or visit www.ctahr.hawaii.edu/UHMG.