Weeds

[Gary S]

Hi all

Happy Easter to all and sundry.

Another bugbear of mine, who amongst us has problems with weeds growing in pots. Does anyone recommend, or has used a commercially available herbicide that can be spayed on or is available in granular form that will eliminate the weeds and not cause any problems to the orchid.

There are a few things available here in Aus. that have been reported to work, but not sure as to any side affects to orchids.

I know Andy will most likely say the greenhouse should be weed free, but not all of us will have that luxury.

Will be most interested on the response to this topic.

Regards
Gary..

[orchids3]

My second cup of coffee goes with me to the shade house each warm morning and one hand looks for weeds to pull and the other holds the coffee until a weed or spike is found. The old Dutch farmer I worked for when I was kid - tought me well to never walk past a weed. My wife's ferns cause the most trouble until I can loose them.
There is an older grower in the Jacksonville Florida area that once wrote an article and published it in the AOS Orchids magazine. The thrust of the article was, if your weeds are healthy your orchids will be
healthy as well. The article offered to send anyone all the weeds seed they wanted if a Self addressed Envelope were furnished.The thing that amused me was that he had a lot of takers. Marv has lots of weeds and some really nice orchids but the orchids are hard to find. Oh yes, If you kill one of the
Rattle Snakes - you are supposed to eat it.

[Albert Nakaji]

Some years ago, one of the university researchers here gave a talk about using a pre-emergent herbicide (Karmex) to control weeds in pots. I vaguely recall something like 1 Tbl spoon/gallon of water. Prior to that talk, I'd also been experimenting on my own and used 1/4 tsp/gal with good results. Although it's a pre-emergent, it killed all of the fern, oxalis, etc. that were growing, as well as keeping more from sprouting for quite a while. Of course, at 1/4 tsp/gal, the effect took a long time, but it worked. At a strong concentration, it works faster, but I always worry about it affecting either the plants or the viability of the seeds in the pods (never tested the hypothesis about the seed in the pods). I also recall that the treatment/chemical was cleared for use in pots for ornamentals in the US.

[Gary S]

Thanks Albert, I will do a bit of research on that.

Apparently there is a flowable selective herbicide available here called Afalon that will kill all weeds and ferns in orchids without any known ill affect to the orchid itself, even orchid seedlings!. Applied at a rate of 2millilitres per litre, its active constituent is 450grams / litre Linuron. Has anyone else had any experience with this .

Also I have been told it works better in the warmer months of the year.

The weeds I have the most trouble with are Flickweed, Pastel Flower, Toadflax and Oxalis.

Andy.

Would like to hear your thoughts on this subject, thanks.

Regards

Gary..

[MrCym]

Don't like endorsing products in the public forum but Linuron is indeed OK if applied at the lowest recommended label concentration and always only onto WELL-WATERED plants. I keep weeds out but if you have to get rid of them, it is the safest chemical to do the job.

[SARC]

Gary

The first thing I would ask you, is do you have any experience or training in chemical application? You quoted 2ml/Litre Linuron at 450grams/Litre active, but no reference to how much area this is suppose to cover!! Alot of herbicides have per acre application rates so you need to calibrate your spray equipment to apply at that rate. So if you apply this Linuron (I have no experience with the chemical) at 2ml/Litre over 20 square yards, but the calibration is for 50 square yards, then you've applied 2.5 times more chemical than is required and may affect your plants. An old turf professor showed me how they can spray couch grass with Glyphosate, kill all the broadleaf weeds and not affect the turf by using the right calibration.

The other big thing is if the chemical is labelled for use on ornamental plants in the greenhouse situation in your state?? If not then you're on your own and technically doing something illegal. If I said I use X chemical on my orchids and its not labelled as such, then I'm also committing an illegal act and your lawyers would have a go at me if you killed all your plants by following my advice! The other thing with preemergent herbicides is they can build up in the soil, so you need to know how often you can apply. From memory (from about 25 years ago) one preemergent herbicide could only be used once per year, it was that resiliant. I think I heard about that research Mr Nakaji talked about, but from memory it work on some types of orchids but killed others. If your going to try anything, read the label and do alot of research prior to trialing it. Know how the chemical works and start with a low concentration, also keep records of when you put it on and at what rate.

Just the other day I was talking to another grower who lost a crop of newly budded fruit trees, a worker was spraying glyphosate around the greenhouse and it was sucked in by the ventilation fans, ouch!!

[MrCym]

I should clarify, I was talking about Cymbidiums only. I have no experience of using any herbicide on any other genus and indeed would never risk one on Odonts for example.

[Albert Nakaji]

The matter of discussing the use of chemicals was held on the previous forum and, indeed, much caution was advised against recommending anything, precisely for the reasons stated earlier. So, for the sake of the legalities, I am not recommending anything, and simply restating my recollection with some research.

[Gary S]

Thanks for the input guys, I do not have the product but will look into it a lot further.

One of the growers in Victoria (who is on Andy's blacklist) has written an article on it in the AOR here a few issues ago, and has trialled it on a number of species and has reported good results, again with all the usual precautions. So he has actually gone to print on it.

If I do decide to get hold of some I will trial it on some orchids that can be sacrificed first at reduced rates to see what happens.

It may not be available in small quantities. I think it is a Bayer product and they have a good technical department you can talk to first on these matters.

Regards

Gary..

[MrCym]

I would take anything "Swurville" or as the Ockers prefer to call him, "Turdsville" says, with a measure of caution. He was let go from Collector's Corner for "transferring" their stock to his property in a common Aussie tradition so a fellow to be cautious believing about anything! You see we try and warn honest people here because they are the future of orchid growing and we try and advance the hobby in the proper way. Of late there has been an active "tea leaf" here in the greater San Francisco area. Some of us feel we know who the culprit is so we wait, knowing they will eventually stumble and be caught.