Wednesday | September 20, 2017
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Avocado inquiries

My avocado trees are about to finish fruiting and are in need of pruning. Is there a rule of thumb on the amount that can be removed?

In general, avocado trees are in need of pruning when the canopy becomes so dense that ample light is blocked from entering the interior of the tree.

This will cause the number of interior blooms to be severely reduced and thus fewer inside fruit. At this point, pruning is needed to thin out branches and let more light in.

Pruning can also occur when the homeowner decides the tree is too tall for ease of picking; topping of the tree obviously controls the height. Some branches can be pruned for individual preference. If trees are severely pruned, the exposed bark will need to be sprayed with diluted, white latex paint in order to protect the tree from sunburn. This is important in hot, sunny locations.

Garden Guy, I have an avocado plant that has fruit on it since summer and it still doesn’t appear to be getting ripe. I bought the two plants at a nursery in Kurtistown. One had a name greengold, U of H hybrid and the other was Yamagata, no fruit yet. The reason for buying these two plants was to extend the fruiting period. I was told that the plant should do well where I live. I was hoping that one of the fruit would fall off so I know it’s getting ripe. Maybe I’m not giving it the right type of fertilizer. Do I need to give it time? I would appreciate any help. Mahalo. — Richard K.

First of all, fertilizer is not the main concern. Let me share some thoughts:

If there is room, it is advisable to have more than one variety of fruit tree, thus extending the harvest period. (With oranges, having a navel and a Valencia orange will give fruit all year around.) Once a young grafted avocado tree is planted, it will take two to three years before it bears fruit. Seedling trees, that is, those that are not grafted, can take up to 10 years before giving fruit.

In some varieties of avocados it is easy to determine when fruit are mature because of external skin color changes, generally from green to black as the fruit matures. The difficulty arises with varieties that remain green when mature.

Some use the indicator of skin tone changing from glossy to dull as the fruit matures. Also the seed coat turns from ivory to dark brown upon maturity.

Sometimes it is advisable to pick one of the larger fruits and keep it at room temperature until it softens. If indeed it softens with good consistency, it truly is time to pick. On the other hand, after sitting on the counter, if the flesh remains tough and actually shrivels, the fruit is not mature and will not be good to eat.

The best place to keep fruit until used is on the tree. Some avocado varieties hold their fruit satisfactorily for several months, others for only a relatively short time.

With some of Hawaii’s hard-shelled types, softness of the fruit itself is not easily determined. Here is a tip: remove the button at the stem and insert a toothpick into the opening. If the meat is soft, the fruit is ready to eat.

It is best, of course, if the fruit variety is known, literature is available stating the harvest period. Greengold fruit is harvested throughout the winter/spring while Yamagata is spring/summer fruit.

Hilo resident Nick Sakovich is a professor emeritus of the University of California. He has worked in the field of agriculture for 30 years. Email your questions to Sakovich at


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