Australian tree ferns: Plant possible invasive concern by Carolyn Lucas West Hawaii Today clucas@westhawaiitoday.com Wednesday, March 18, 2009 9:07 AM HST Though prized for its distinctive looks and rapid growth, the Australian tree fern is becoming an increasingly common and alarming fixture in Kona neighborhoods, according to a recent islandwide survey by the Big Island Invasive Species Committee's early detection crew. On the underside of its triangular fronds with lacy blades are millions of spores, which breezes -- as well as feral ungulates -- carry far and wide. This tree fern (Spahaeropteris or Cyathea cooperi) is already displacing native forests on Kauai, Maui and Oahu. Watersheds are also being choked. Such propagation is just beginning on the Big Island, said Page Else, spokeswoman for the Big Island Invasive Species Committee. "The tree fern crowds out our native hapuu, the mother of the forest. The soft fibers of the hapuu nurture young native seedlings of native plants like ohia and olapa," she said. "The Australian tree fern has a harder, scaled trunk which doesn't make a good home for seedlings. Consequently, the foreign plant can take over in our forests, changing the forest structure, lessening the number of native plants and decreasing the ability to capture water and provide good water quality in watersheds." It's no wonder that the Australian tree fern appears on a list of the most invasive plants in Hawaii, prepared by the Hawaii State Alien Species Coordinator and the Department of Land and Natural Resources' Division of Forestry and Wildlife. Officials urged people to not cultivate any of the listed species anywhere in Hawaii. The Big Island Invasive Species Committee recently issued an Australian tree fern alert, spreading awareness about the weed and hoping that residents will help prevent its spread. People should report tree ferns by calling the state pest hotline at 643-7378. Those who have purchased the popular ornamental but suffered buyer's remorse and now want to remove it can either snip the bud or cut down the tree fern and treat it with herbicide. "They should be aware that their tax dollars will be put to work combating the rapid growth of this plant in public watersheds as seeds spread out of their yard into other locations," Else said. Two years ago, the Kauai Watershed Alliance contracted the Nature Conservancy to coordinate a response to the invasive tree fern. Crews on foot are sent into valley uplands to remove plants at a cost of $365 per acre. Helicopters with herbicides spray in more remote, dangerous areas. The aerial spraying costs $560 per acre, Else said. James Leary, invasive weed specialist at University of Hawaii at Manoa College of Tropical College Agriculture and Human Resources, has been experimenting with an innovative way to apply herbicide selectively to Australian tree ferns by using paintball guns with a special pesticide formulation. While people may be fond of the tree ferns, a wide variety of noninvasive alternatives, including the native hapuu, can be used as ornamentals. Because each yard is different, residents can visit a nursery and talk to an expert to find the best fit. Many nurseries -- including 15 on the Big Island -- agreed not to sell the tree fern after learning its potentially detrimental impact. For more information, call the Big Island Invasive Species Committee at 933-3345.

Thanks for the tip! I do always pasteurize my seed starting soil by wetting it, then microwaving it for 8 minutes, then letting it sit covered until cool. I did this for the ferns. Plus I washed the trays and covers with a dilute bleach solution. I must've not been thorough enough, or there was something in the air. I've been peeking, so some fungal spores could have gotten in. I decided to scoop out the fungal/mold areas with a kitchen spoon. So far, no re-growth. We'll see. I've used hydrogen peroxide with veggie and flower seedlings a couple times in the past, though I really don't have problems with molds in my seedlings. The Ostrich Fern is showing some signs of growth now. Fingers still crossed! I found this great article by Bill Cullina about growing ferns from spores, in case anyone is interested. Here is a link that might be useful: NEWFS on growing Ferns

First image: side view; Second image: top view; Third image: isolated close up Any ideas as to what they are? When I checked my 10 gallon moss/fern/lichen terrarium this morning, I found these odd new spore like growths over 85% of the terrarium. They are brown and growing on everything except bark, branches and the glass. They popped up in between barren spots in wild collected moss, but not on a large piece of moss covered bark. They are on the soil, rocks and perlite. There is absolutely no mold anywhere and the moss, lichens, ferns and ivy are all healthy. I use organic soil, only bottled spring water and have treated very successfully with fenbendazole to eliminate fungus gnat eggs and larvae. The tank is never closed completely, but always left half open. There is no condensation on the glass. It is layered with pebbles, charcoal, fine screen and soil on top. I keep an 8 watt T5 florescent fixture on top of the tank for about 8 hours a day. Has worked just right so far. I let the terrarium "do its own thing" basically and have mixes of wild caught moss and tiny ferns. I uprooted a "frosty fern" about a week ago as it looked terrible in the tank and would have taken over the entire tank if left to its own devices. I planted a few pieces of various rooted ivy cuttings in its place. If someone can identify whatever these spore like growths are and confirm they are not going to destroy the rest of the terrarium, I'll leave them. I'm just afraid when these things "pop", I may have to do the entire 2 year old terrarium over. Thank you!

check out this article growing lycopodium from spores