This year’s avocado defoliation due to the avocado lace bug continues to raise havoc with fruit production. Exposed fruit are quickly sunburned and that affects the quality.
University of Hawaii entomologists had hoped that this season might be better with natural predators reducing the lace bug population. So far, this does not seem to be the case. Avocado trees all over the island are again prematurely losing their leaves. The leaves turn brown and in many cases the trees lose all their leaves. This condition is likely due to the avocado lace bug.
This insect was first noted in December 2019 on Oahu and has spread throughout Hawaii Island in 2021. Lace bug infestations will probably reduce crop yields and may even kill trees weakened by other stresses like root damage, nutritional and water issues. Natural predators of the avocado lace bug are present in Hawaii, so it was hoped this infestation would be corrected.
If you decide to spray your trees with a pesticide, be sure it is cleared for use on avocado trees and don’t apply while the trees are in bloom or you will kill bees and other pollinators. Check with the University of Hawaii College of Agriculture Extension Service to make sure you use the right pesticide at the right time. In Hilo, the number is (808) 981-5199 and in Kona, call (808) 322-4893.
But don’t give up on growing avocado trees in your garden.
Avocado trees are ideally suited for Kona’s dry winters and wet summers, as well as our well drained soils in rainy regions. However, they do well in wetter locations as long as the soil is not soggy or poorly drained.
Fat has a bad reputation in today’s health-oriented society, but fats are essential to our well being. It’s just that some fats are better than others. Avocados are among the most healthy sources.
No Hawaiian garden is complete without an avocado tree for shade and fruit. It is unusual in storing its food chiefly in the form of fat and protein instead of sugar as nearly all other fruits do. The fruit is very high in vitamins and minerals. It is especially high in phosphorous, vitamin A, riboflavin and niacin. The fat contains no cholesterol.
The avocado is a fruit native to the Americas that was growing wild from southern Mexico to Ecuador and the West Indies at the time of Columbus’ arrival. Just when it was introduced into Hawaii, no one really knows, but it has naturalized and may be commonly found where conditions are favorable.
Avocados are now found on the markets all over the country at all times of the year. The major Florida crop comes on the market from June to February and the California crop from January to June. Hawaii has fruit all year round.
The avocado is borne on large evergreen trees with large, somewhat leathery leaves. This tree is tolerant of a wide range of soil types, but it must be provided with good drainage. Flowers are produced in late winter or spring, and the fruit matures in anywhere from 6 to 18 months, depending on location and variety. The avocado may be left on the tree for some weeks after it first matures with comparatively little dropping.
The avocado is a little strange when it comes to sex and fertilization. For example, the flower opens and closes twice. At its first opening, every flower behaves as if it were a female flower only, able to be pollinated but not able to shed pollen. Then it closes for 12 to 24 hours, and when it opens again it is essentially a male flower, shedding pollen but usually no longer in condition to be pollinated. Furthermore, all of the flowers on a tree open and close almost at the same time and all the trees of a given variety behave just alike, and their flowers open or close together. This makes interplanting of two or three varieties a very important practice.
Even after more than 100 years of culture in Hawaii, there is no one variety or set of varieties that is wholly satisfactory. Each has its faults and advantages. Sharwil, Yamagata, Murashige, Ohata, and Kahaluu are local favorites.
If you are in a hurry, avoid seedlings and grow grafted trees. Seedlings grow quite tall and may take 7 to 12 years to bear fruit and then you may not get good quality fruit. Grafted trees are carried at some nurseries. Grafted trees begin to bear in two years and are not as tall.
Avocados may be planted successfully at any season of the year but spring is the best time. Frequent irrigation is necessary though, until the tree is established. Remember that avocado trees do not like saline water or soggy soils. Choose a rich, well drained soil. Strong winds will cause leaves to burn or shed. If your soil is poor, mix in peat moss and well rotted manure to improve it. Shading and wind protection of newly planted trees is important to give them a good start. Avoid planting avocados near the ocean exposed to winds and salinity.
Hopefully the avocado lace bug infestation will soon be controlled naturally and abundant crops will soon be back.
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Norman Bezona is professor emeritus, University of Hawaii College of Tropical Agriculture and Human Resources.