Aloha Professor Sakovich. I love your articles in the Hawaii Tribune-Herald! I have a problem with my yard in Hilo. Zoysia El Toro grass makes up the lawn, and up to now it has been wonderful, weedless and beautiful. Lately I started getting brown spots that have now spread over much of the yard. I have tried insecticides and fungicides to no avail. I do dethatch every six months, and it is due again soon. I’m thinking of dethatching and then spreading a thin cover of lime and compost to “sweeten” and enrich the lawn. Any suggestions? — Thank you, C.S.
Turf problems are one of the hardest to diagnose. It could be insect pests – cutworms, armyworms, wireworms, some beetle larvae called grubs and others, or diseases — a variety of fungal pathogens attack lawns. To discover if insects are feeding on the roots of the lawn, try this test. Put one ounce of liquid detergent in one gallon of water and sprinkle this solution on one square yard of infected turf. Within a few minutes, most worm pests, grubs (beetle larvae) and caterpillars (moth and butterfly larvae), will come to the surface because of skin irritation. Wait a maximum of 10 minutes. One or two worms usually do not indicate a problem. Depending on the pest, six to12 worms would indicate a problem. The worms can be identified through the publications listed below or at the University of Hawaii College of Tropical Agriculture and Human Resources Extension Office. In many cases, the infected lawn will have to be treated with an insecticide. Don’t forget to douse the area with water to flush out the detergent. Perhaps the best advice is to start by downloading two University of Hawaii CTAHR publications, “Destructive Turf Caterpillars in Hawaii” and “Turf and Ornamental Pest Control.” These will help you to identify problems in turf. In addition, you can always bring samples to the extension office on Komohana Street. There is a charge for diagnosing certain problems.
I have a question regarding my pomelo tree, which was planted around 1982. In the beginning, the fruits were the size of basketballs (this is the ruby variety). Now they are the size of grapefruits. I was told the tree is sick and probably should be cut down and tossed. Would you agree? — T.
First of all, we have to get our fruit straight. The word pomelo is Spanish for grapefruit. I don’t know of any varieties of true pummelos that are named ruby. There is, however, a variety of a grapefruit that is called ruby. So it is quite possible that the tree you have is a grapefruit and not a pomelo, and what you have is normal for the fruit size. Oftentimes, a tree will produce some extra big fruit when it first yields. Poor health, however, is a major contributor to small fruit size. The tree is 30 years old, and that’s old for a tree. A myriad of diseases could be working within it. Depending on how poor the foliage looks and how much fruit the tree is giving, removing the tree is certainly a consideration. Remember that when purchasing a new tree, make sure it is budded on a rootstock that is resistant to root-rotting fungal organisms.
Note: As long as the tree is not infested with disease organisms, theoretically it can live a very long time. Some citrus trees in California and Florida are close to 100 years old. California’s original navel orange tree planted in Riverside in 1873 still stands.
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.
