It’s “what’s growing on” in Halawa Valley
By: Mapuana Hanapi
Almost every person on Molokai has hiked the Halawa trail once. For those people who remember it when there were no signs of invasive pests, they can tell you how beautiful it was. Now there are many invasives threatening the environment along the trail and one in particular that can really hurt a person. It is called the Barbados Gooseberry and it has some really nasty thorns that can ruin any hikers day.
Gooseberry looks like a vine but is really a cactus that came from the West Indies. It starts as little woody lianas and grows into thorny vines that can climb up trees. Once reaching the top of the tree this plant can form a dense, spiny thicket smothering out other plants. The thorns are 1-2 inches long and form clusters along the vine.
Have you ever seen a wana (sea urchin) in the ocean? Well picture the older gooseberry covered in dozens of "wana" attached to the entire vine. Definitely not something that anyone wants to mess with. The younger plants have thorns but they aren’t as nasty as the older vines. Gooseberry has 2-4 inch long, eye-shaped leaves that are a dark glossy green.
On the mainland this plant is reported to have flowers that are white, yellowish or pinkish, but the plants in Halawa have never been seen with flowers or fruit. Gooseberry has ½ inch wide fruits that are round or oval and yellow, orange, or red in color. It can be spread through seeds or various plant parts (leaves, stems, etc.). A person can mistake the younger gooseberry for maile. The major difference between them is the thorns.
MoMISC has been controlling and trying to eradicate this thorny vine for many years. There are multiple populations that have been established near the river. All populations have been reduced and kept under control.
MoMISC first started controlling the big populations by cutting the bottom of the cactus and applying herbicide. This killed the roots but left some of the cactus growing in the tree tops above. The smaller younger cactus was sprayed with herbicide which was very effective in killing them.
To deal with the tree top cactus we tried to attach latex products filled with herbicide at the cut ends, hoping that the cactus would drink the herbicide thus killing the plants up above in the tree tops. This proved to be only somewhat effective in eliminating the cactus in the tree tops. In order to eradicate the gooseberry in the treetops we may have to take those trees down.
When we first dealt with the populations we enlisted the help of other organizations and volunteers. We would like to thank those organizations and volunteers for all their help, you know who you are. With a staff of only two field workers we can only do so much and having help from the Molokai community is greatly appreciated. Now the Gooseberry populations are being checked every six months for regrowth. We can say with confidence that all the known populations in Halawa will be eradicated in the future.
MoMISC is asking the Molokai community to report any sightings of Barbados Gooseberry by calling 553-5236 ext. 204. We will ask for your name, phone number, mailing address or e-mail, pest location, how many you saw, and if any action was taken. It would also be helpful if you could photograph and take samples of the plant. Please don’t grow gooseberry. Instead, try growing native plants. For more information about Barbados Gooseberry visit www.hear.org or the Ho`olehua Airport kiosk during the months of December and January.