Dear Garden Guy, I live in Paradise Park and have a number of both grafted and wild avocado trees, but I don’t know the exact varieties. In mid-January, I finished harvesting the last of the fruit from a bumper crop from many of the trees, but not all. Now, only a few weeks later, every single one of the trees is in flower. I have not seen them flower this soon after fruiting. Is this out of the ordinary? Perhaps this is a result of the recent climate; a very wet Nov. and Dec. with very dry January. Thank you for your assistance. Aloha, Mary
Avocado trees, as well as citrus, will bloom at the same time each year — late winter and early spring. Within this time frame trees can vary in their bloom usually due to weather conditions. The fruit of some varieties will be ready to harvest in less than one year from bloom, while other varieties require a full year and more to mature. As a result, a tree can carry two crops at once — fruit from last year’s bloom, which is now ready to pick and small immature fruit from this year’s bloom. Or, as in your case, the old crop has just finished as the new bloom comes on. This is also the case with some varieties of citrus; a tree will carry newly set fruit along with last year’s crop, which is just beginning to mature. Lemons are unique in that one tree will be supporting flowers, tiny young fruit, older green fruit and mature yellow fruit, all at the same time.
This is why both avocados and many citrus trees alternately bear — a heavy crop one year, followed by a lighter crop the next. If the tree is carrying a heavy load of fruit when it is time to set bloom and begin producing more fruit, then the new bloom will be light — there is only so much energy to go around. On the other hand, if last year’s crop was light, and it is time for the tree to bloom again, it will produce and hold a large crop.
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Dear Garden Guy, I have several beautiful red hibiscus plants. They have healthy looking flowers, but the leaves have big dark spots with yellow circles around them. These really detract from the appearance of the plants; do you know what causes this and can it be “cured”? Thanks, a Fan
Most gardeners complain about the grotesque looking bumps on hibiscus leaves, caused by the erineum mite. There is, however, another disease which triggers angular brown to black spots, typically measuring ¼-inch across. Yellow halos develop around each spot. It is called bacterial leaf spot of hibiscus, caused by Pseudomonas cichoril. The disease occurs on the most commonly grown hibiscus, Hibiscus rosa-sinensis, also known as Chinese hibiscus and tropical hibiscus. It is relatively common in high rainfall areas. It is the rain droplets which disperse the bacteria. Severe spotting can cause premature leaf drop; the flowers are not affected. Here’s what can be done:
— Periodically remove diseased leaves and discard along with the leaves that have fallen on the ground; the bacteria can survive on the fallen leaves.
— Routinely prune to open up the shrub for rapid drying of the leaves.
— Avoid planting in shaded areas.
—Avoid overhead irrigation.
— Copper fungicides may be used to protect uninfected leaves but may not be effective in areas with high rainfall.
Gardening Class
I am teaching a class titled “Vegetables in the Home Garden,” from 9:30 a.m.-noon Saturday, April 28, at the University of Hawaii at Hilo, Room UCB 114. Call 974-7664 or go online to register at http://hilo.hawaii.edu/academics/ccecs/registration/. Cost is $20.
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 askthegardenguy@earthlink.net.
