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The Honolulu Advertiser
Posted on: Friday, September 2, 2005

Avocado trees more productive with nurturing

By Jari Sugano

Knowing when an avocado is ripe can be tricky, since different varieties give different signals.

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Avocado is a widely used fruit in Hawai'i. With its smooth, nutty and buttery consistency, it is found in dishes from guacamole to sushi.

Avocados flourish in well-drained soils with a soil pH of 6.2 to 6.5, slight acidity. Adequate tree spacing of 25 to 35 feet is necessary to achieve optimal growth and yield.

Avocados have a strange flowering behavior that sometimes results in poor fruit set by individual trees. Trees have flowers designated as Type A or B. Growing more than one avocado variety (with different flower types) encourages cross-pollination between trees. Guatemalan, Mexican and hybrids of West Indian varieties grow well in our warm climate. Recommended varieties for Hawai'i's home gardens include: Greengold (A), Sharwil (B), Kahalu'u (B), San Miguel (A), Murashige (B), Hayes (A), Nishikawa (B), Malama (B), Semil-34 (A), Nabal (B), Frowe (B) and Case (B).

To ensure consistent growth, yield and varietal characteristics, avocados are primarily propagated via grafting. Trees will begin to bear fruit about three to four years after transplanting.

Place a handful of treble superphosphate (0-45-0) fertilizer along with a generous amount of decomposed organic compost in the planting hole. Apply a complete fertilizer such as 16-16-16 two to three times a year until flowering.

After flowering, apply a 10-5-20 or 10-20-20 fertilizer monthly around the drip-line area. As a general rule, annually fertilize with about 1 pound for each inch in trunk diameter.

Split fertilizer applications into three to four applications per year and apply around the drip line of the plant.

Determining when avocados are ripe is a difficult task. Each variety of avocado ripens differently. Changes in skin color, looseness and shine are indicators of ripeness.

Avocados often are picked mature and allowed to fully ripen on kitchen counters. Avocados are harvested using hand poles or shears, leaving some of the stem on the fruit.

After harvest, prune back branches to promote air circulation and regrowth. Avocado root rot is the most prevalent disease of avocado trees. To minimize root rot, prevent excess buildup of moisture and increase soil drainage. Thrips, mites, fruitflies, black twig borer, algal leaf spot, stem rot and anthracnose are additional pests of avocados.

For specific crop and pest management recommendations, consult the University of Hawai'i's College of Tropical Agriculture and Human Resources master gardener program or visit our free publication Web site at www.ctahr.hawaii.edu/freepubs.

When buying avocados, look for the Island Fresh label. Island fresh mo' bettah.