Some questions that appear here were originally directed to Kona’s Certified Master Gardeners.
You may contact them with questions at konamg@ctahr.hawaii.edu.
Patty asks: Something is eating shot holes in the leaves of my young variegated hau tree. Do you know what it is and how I can get stop the damage?
Tropical Gardener answer: It sounds like the Chinese rose beetle (Adoretus sinicus) is damaging the leaves of your hau tree. These beetles attack over 250 plant species and are common pests here in Hawaii They live in the soil during the day and come out to feed for a few hours just after sunset. Sometimes their feeding leaves only the leaf veins in place. Shot holes or a lacy leaf appearance are also evidence of the Chinese rose beetle’s presence.
The best way to positively identify them is to catch them in the act. If they are responsible for the damage you will likely find them feeding on your plant just after sunset. The beetles are reddish brown and about a half inch long. Collecting them is probably the best way to stop the damage. Don a head lamp and some gloves and take a jar filled with alcohol to your damaged plant around 30 minutes after sunset. Remove any beetles you find and drop them to their death in the alcohol.
If night time bug hunting doesn’t appeal, you can use neem oil fertilizer at the base of the affected plants and neem oil mixed with safer soap as a foliar spray. The soap and oil must contact the insect to kill it, but the smell of neem oil seems to serve as a deterrent. Some systemic insecticides list these beetles as target pests. Use these products with caution. Most of them are not suitable for use on edible plants and they will kill off good bugs as well.
You can also deter Chinese rose beetles by shining a bright light on your plant at night. If it is too far from electricity, try encircling the plant with solar lights. Some damage reduction has been reported using lighting as a deterrent.
Though these beetles are known to attack young hau trees, they usually move on when the trees get older. Do take some action to deter rose beetles, however, as the leaf damage reduces a plant’s ability to photosynthesize and will compromise its health.
Diana Duff is a plant adviser, educator and consultant living on an organic farm in Captain Cook.
Gardening Events
Tuesday: “Coffee Berry Borer Workshop” from 3 to 5 pm at the UIH Cooperative Extension Service office, 79-7381 Mamalahoa Highway in Kainaliu. Updates and best management practices plus information and sign-ups for the Beauveria subsidy program. Get more information and RSVP at least 3 days prior at http://hawaiicoffee.weebly.com/2016-cbb-workshops.html or contact Gina at 808-322-4892 or ginab@hawaii.edu.
Wednesday: “Olive Oil Production Tour and Workshop” from 12:30 to 4:20 pm starts at
Lālāmilo Experiment Station, 66-1170 Opelo Road in Waimea. $10 donation to: UH Foundation Account #127-2160-4. Reservations required. Contact Kiersten Akahoshi at Kiersten@hawaii.edu or Komohana CES Office at 808-981-5199 ext. 201
Friday: “Food Safety Modernization Act Workshop” from 3 to 5 pm at UH Cooperative Extension Service office, 79-7381 Mamalahoa Highway. Covering the FSMA produce rules and on-farm good agricultural practices (GAPs). Free to registered attendees. Register at https://www.eventbrite.com/e/big-island-statewide-fsma-informational-session-tickets-20048845637
Saturday: ““Coffee Berry Borer Workshop” from 3 to 5 pm at the UH Cooperative Extension Service office, 79-7381 Mamalahoa Highway in Kainaliu. Updates and best management practices plus information and sign-ups for the Beauveria subsidy program. Get more information and RSVP at least 3 days prior at http://hawaiicoffee.weebly.com/2016-cbb-workshops.html or contact Gina at 808-322-4892 or ginab@hawaii.edu.
Farmer Direct Markets
Wednesday: “Ho’oulu Farmers Market” 9 am to 2 pm at the Sheraton Kona Resort & Spa at Keauhou Bay
Wednesday: “Sunset Farmers Market” 2 pm – sunset at the north makai corner of the Kmart parking lot.
Saturday: “Keauhou Farmers Market” 8 am – noon at Keauhou Shopping Center
“Kamuela Farmer’s Market” from 7 am to noon at Pukalani Stables
Sunday: “South Kona Green Market” 9 am – 2 pm at Amy Greenwell Garden in Captain Cook
Monday–Saturday: “U-Pick greens and produce” 10am to 4pm Tropical Edibles Nursery, Captain Cook.
Plant Advice Lines
Anytime: konamg@ctahr.hawaii.edu
Thursday: 9 am to noon at UH-CES in Kainaliu – 322-4892
Mon., Tues. & Fri: 9 am to noon at UH CES at Komohana in Hilo 981-5199 or himga@hawaii.edu