Sarah asks: I lost a few macadameia nut trees in the recent windstorm and was wondering what I can do to protect my other trees from damage from high winds in the future.
Tropical Gardener answer: Macnut trees are known to be shallow-rooted. Reports of them toppling in high winds are not uncommon. Given their growth habit, they should be planted in areas where they are or can be protected from high winds. Planting them in dips in the landscape, small valleys that are protected by higher surrounding areas, is a good idea. Where that is not possible, surrounding them with tall plants that can offer windbreaks is advised.
Several species that have been used as windbreaks in the past are no longer recommended due to disease pressure on them or their risk of becoming invasive. Tropic coral (Erythrinia variegate) that was used extensively on Maui and Molokai should not be used where the Erythrinia gall wasp is present. Ironwood is a formerly popular windbreak tree that is now determined to be somewhat invasive.
A fast-growing alternative to these might be either podocarpus (Podocarpus gracilior) or a clumping bamboo that has edible shoots, like Bambusa oldhamii. Native tree species that show tolerance to strong winds include both milo and kou. The nitrogen-fixing gliricidia, if grown closely spaced, is another possibility. Banana trees can also offer an edible windbreak, if grown close together. Panax, with a columnar growth habit similar to the tropic coral is another alternative but it only grows to about 15 feet. A UH-CTAHR publication from 1982 lists quite a few windbreaks with some notes added about their invasive potential in 2012. You can find it at https://www.ctahr.hawaii.edu/oc/freepubs/pdf/C1-447.pdf.
Though some of the species listed in the old publication may be hard to find, the state Department of Land and Natural Resources nursery in Waimea sells seedlings of lots of windbreak trees. You can find the list of what’s available, as well as descriptions of the trees they sell, at http://dlnr.hawaii.gov/forestry/files/2013/09/nursery-species-list.pdf.
Though windbreaks may take a few years to get established and become tall enough to protect your macnut trees, getting them in the ground and started now can prove beneficial in future windstorms.
Email plant questions to konamg@ctahr.hawaii.edu for answers by Certified Master Gardeners. Some questions will be chosen for inclusion in this column.
Diana Duff is a plant adviser, educator and consultant living in a dryland forest north of Kailua-Kona.
Gardening Events
Tuesday: “Agrilogic Crop Insurance Webinar,” 9 to 10 a.m. Join from your computer, tablet or smartphone: https://global.gotomeeting.com/join/317952869. You can also dial in via phone: (872) 240-3212, Access Code: 317-952-869. RSVP by email to Hawaii@agrilogic.com. Information on the crop insurance programs available to Hawaii agricultural producers will be given.
Saturday: “Work Day at Amy Greenwell Garden,” 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers should bring a brown bag lunch. Water and snacks provided. Call Peter at 323-3318 for more information.
Farmer Direct Markets
Wednesday: “Sunset Farmers Market,” 2 p.m. to sunset at the north makai corner of the Kmart parking lot
Wednesday and Friday: “Hooulu Farmers Market,” 9 a.m. to 2 p.m. at Sheraton Kona Resort and Spa
Friday: “Pure Kona Market,” 9 a.m. to 5 p.m. at Amy Greenwell Garden in Captain Cook
Saturday: “Keauhou Farmers Market,” 8 a.m. to noon at Keauhou Shopping Center
“Kamuela Farmer’s Market,” 7 a.m. to noon at Pukalani Stables
Sunday: “Pure Kona Green Market.” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook
Tuesday through Saturday: “U-Pick greens and produce,” 10 a.m. to 4 p.m. Tropical Edibles Nursery, Captain Cook.
Plant Advice Lines
Anytime: konamg@ctahr.hawaii.edu
Tuesdays and Thursdays: 9 a.m. to noon at UH-CES in Kainaliu, 322-4892
Mondays, Tuesdays and Fridays: 9 a.m. to noon at UH CES at Komohana in Hilo, 981-5199 or himga@hawaii.edu