Since its been in the media lately.... opinions on this topic?
http://www.freshplaza.com/news_detail.asp?id=23699
not sure if I put the link in correctly.
wasps to control the strawberry guava in Hawaii
Your link worked beautifully! Interesting article Generally I am against bringing in anything into the islands - we have had such a poor record in the past of things getting out of hand, despite our thinking we know what we are doing...
I will be very intersted to hear others opinion, especially from areas that the guava has taken over - for us in Kihei, I wish we could get rid of the darned kiawe trees or the land developers!
BHM,
One of the reasons some want to rid the island of the strawberry guavas is that pigs feed on them. My worry is what will the pigs feed on if they dont have the guava. There are the strawberry guava in the forest abutting my property and my kids love to pick/harvest them. I worry that the wasp could mutate and destroy other crops. Its a really tough situation.
Just read that pigs are responsible for dispersing 8,000,000 Strawberry Guava seeds in their droppings during one month of the fruiting season - WOW!
Also read that SG is thought to release a toxin that prohibits other plants growing near them, making it much easier for them to take over whole areas.
Still not convinced that imported wasps are the answer though...
Hey Mlassi, it is not a wasp they are releasing, but a scale insect. Tracy Johnson has a website talking all about it. It will stop the guava from reproducing but won't kill it. There will still be too many guavas around, so you won't miss them.
My concern is that Psidium cattleianum, the strawberry guava, is closely related to Metrosideros polymorpha, our native 'ohi'a. I worry that the scale insect might attack 'ohi'a trees and other members of the Myrtle Family. Tracy Johnson insures it won't happen, but the promoters of mongoose, cane toads, and several other "helpful" introductions were sure their critters would do what they're told as well.
Strawberry guavas need to be controlled, for the good of our 'ohi'a forests, I just hope that this biological experiment works out; usually they don't!
Good point Jen!
When pigs feed on strawberry guava fruit, they make a new stand where-ever they take a dump.
The leaves are phytotoxic and ruin the soil for native plants as they decompose.
You would think with the reading I have been doing, I could at least mention the correct type of insect. I didnt realize the pigs spread them that much. Yikes. I worry too about the ohi'a being a target later on. Are regular guava leaves phytotoxic too?
Good guava question Mlassi!
The leaves of Psidium guajava are phytotoxic, as their accomplice Psidium cattlianum.
Interestingly, the common guava has been in Hawai'i longer than the strawberry guava. It is an invasive alien plant, but has not become the aggressive rainforest problem that the strawberry guava now presents.
It is common for members of the Myrtle Family to litter the ground with phytotoxic leaves. Strategically this keeps intruders from encroaching on their turf! You will notice that many plants do not do well under the canopy of Myrtle Family plants in Hawai'i. This is true of Psidium (guavas), Melaleuca (paper-bark & tea tree), Eucalyptus (gum trees), and even our native Metrosideros ('ohi'a).
By being phytotoxic, a plant can be effective at choosing who it's neighbors will be!
If you like to grow ferns, and you mulch them with 'ohi'a leaves, you will have few weeds and the ferns will thrive!
The problem pending is that Psidium cattleianum, the strawberry guava, is fast spreading, highly invasive, and phytotoxic to the point of discluding most everything in the forest but itself!
We will never get rid of strawberry guava. If it is not controlled, it will be the demise of our rainforests.
Aloha, Dave
Hmm, Interesting about the decomposing SG leaves because I've never noticed it to cause phyto in my ornamental plants, but maybe it doesn't affect everything and we do clean them up more than would in a wild setting. Anyway, releasing a scale into a new ecosytem to control one plant is scary! I have never known a scale to be species specific in their attack on plants, and even then although some scale can be very devastating, most species do not kill plants- just distort them or make them unsightly. I also would really have to question the methods under which research is conducted- I can't tell you how many times I have said that just because it isn't reproduced under laboratory conditions does not mean it won't happen in the wild. I worked with an entomologist one time and we were trying to establish eriophyid mites on benjamina (these are more commonly a species specific pest) because I had observed them on benjamina when they were supposed to only affect nitida. They just wouldn't transer from the affected cuttings I brought to the tree in the lab- at least not without a year and half of trying under the right conditions.
I am a huge supporter of biocontrol and one thing that does often make sense is to introduce a parasitoid wasp or beetle that affects pest insects and typically those guys evolve by feeding on only one species of pest. Introducing a plant pest, however, is really scary to me. You just never know what it is going to really do once it gets into a new ecosystem.
Cross posted with you. And that explains it- one thing we have plenty of at our house is ferns. Another thing that is interesting, I've heard about SG's invasiveness before, but wondered why it doesn't pop up all over the place at our property like Brazilian pepper does. I guess it's the pigs. And the birds do eat the Brazilian Pepper to some degree. Only thing I've seen on the SG here are worms- they get to it so fast it's hard to get an edible fruit.
Wouldn't it great if someone could develop a sterile SG, then we could have our cake and eat it too! Still doesn't help with the problem we have now, I just SO don't think we are smart enough to be let loose with biological controls, been there and done that and look what we have done in the past!
I don't have a SG but have several other types of Guava in the garden. They are all pests as far as I am concerned, seeding everywhere there is a drop of water and they seem to attract the Oriental fuit flies too. I get a huge kill in the traps next to the guava trees, far more than next to any other fruit tree.
Hey Fauna4flora, the worms are just reconstituted fruit. Why not make smoothies?
What is Brazilian Pepper?
Thanks for the info Dave! My chicken help keep the flies away.
Brazilian peppertree - yet another thug! We had one of these beasts in the garden and as soon as we chopped it down it grew new trees all along it's root system. I am still battling it after 3 years, soon I will resort to something like stump gone (or whatever it's called)
Oh Dave, reconsituted fruit smoothies! I have a strong stomach, but not that strong!
Alright, metro. I am going to go totally girl on you- ewwww! My girlfriend talked about submerging the fruit to drown them and force them out, but I have never bothered to do that- subsequently I still don't even know how SG tastes!
What is Brazilian Pepper? The bane of my existence. Scientific name Schinus terebinthifolius. If you don't have it in Haiwaii, trust me, thank your lucky stars even though I know you guys have enough invasives on your hands. SoFLa is another gateway to invasives, and lately it seems like a floodgate, at least with the amount of new serious insect pests we've received in just the last 3 years. Brazilian pepper seeds anywhere in any crevice, is profuse, grows like a you know what, and the WORST worst worst thing is the Solanopsis ants that are everywhere all over that plant. They get on other plants, too, and lately it seems like they are on everything and we are all getting bitten way too much....but my understanding is they came with the Brazilian pepper or at least are linked to it in so much that they farm honey dew producing scale, and there happens to be a scale that loves brazilian pepper. And believe me the BP isn't inhibited in the least by the scale. The 3 live together in an evil little tryst- invasive plant, scale and wicked little ant. There is only one small redeeming quality about the BP, and that is it aids a lot to the seclusion of this property, but I was incorrect in assuming that those nasty little ants just keep to the BP. They nest under my grow pots and they are all over the Thunbergia, and literally any plant that I have grown this year they explore and march every inch of it until a bit of scale happens to land and then they claim that plant, too. They are tiny and hard to notice, so I could be performing any routine garden activity and get bit at any point in time. They burn terribly although it doesn't usually form a bump or abcess the way regular fire ants do- and at least with fire ants you see a mound or something. The Solanopsis also seem to swarm at any given day- my son can jump on the hammock 364 days out of the year.....but that one day there they are all over his shirt. Ughh!
Interstingly, I hear that in California this plant is an ornamental that does not get invasive in their climate. So I hear. I've even heard that in Hawaii ficus don't form air roots like they do in SoFla- a temperature rather than rainfall thing so I'm told.
This message was edited Jul 12, 2008 8:55 PM
Chiming in here - . With the proliferation of the strawberry guava and the fact that the insect does not destroy it but simply 'controls' it....I don't think (humility is not my strong suit) it/them will ever run out of SG. There will still be stands of it to cut from and the kids who pick them up simply will find something else....grow a better guava that is not invasive.
I AM against trying out alien species to control our environment...and i believe science has come a lot further since the mongoose and cane toad mistakes!!!!
YES...the ficus DO send down aerial roots in Hawaii!
Carol