So I mixed up my own sulphur spray...

[ALToronto]

Put 15 ml of powered sulphur (Green Earth fungicide / miticide) in a litre of water, shook it up and sprayed all my orchids. Several phals were showing signs of being eaten by mites, so I decided to take no chances - I figure it can't hurt even if I don't have mites.

The homemade spray turned out to be much more concentrated than the pre-mixed spray I had been using (also by Green Earth). So now my plants look like I had them behind the rear wheels of a Jeep, spinning in white mud.

My questions:

Is dried-up sulphur slurry doing anything against mites? I'm sure it helps as a fungicide, but wouldn't it need to be wet to kill mites?

Do I need to re-spray with sulphur in a week, or can I re-activate the sulphur by spraying with clean water?

Should I leave the sulphur on the leaves, or am I more likely to kill the mites by washing and wiping the leaves?

 

[Justin]

i would use something a lttle stronger. pyrethrines are good against mites and relatively safe for mammals. be sure to spray undersides of the leaves too.

 

[consettbay2003]

Powdered sulphur will have a 'drying' effect on the leaves which is a condition that mites prefer. You would have more success in dealing with mites by using an insecticidal soap.

 

[ALToronto]

I don't think soap is very effective - I've had it let me down before. I'll try pyrethrin. Should I be spraying the medium as well (sphag/lava rock), or just the leaves?

 

[Justin]

spray the top of the medium, in the leaf axils, and underneath the leaves.

keep in mind most pyrethrins are mixed with horticultural oil, so turn the lights off until it dries.

treatments 7 days apart should do it.

 

[John M]

Why would you use sulphur for mites? It's effective as a topical fungicide; but, I haven't heard of it being for mites. By far, the best thing I've ever used for mites, in my 30+ years of growing orchids, is horticultural oil. Green Earth is the brand I'm currently using. The label says you can use it at 10 ml per litre for spraying plants while in growth. I use it at 15 ml per litre; but, NOT more. You don't want to clog the stomata and suffocate your plants; you just want to suffocate your mites. It does a fantastic job at killing mites....and your plants don't get that "covered in mud" look! It's made of a very high grade mineral oil with a bit of emulsifier to help the oil mix with water. So, there isn't any toxicity issues for you when using it. It's even WAY better than using things like Pentac, or other chemicals.

I have a very mixed collection and I have never had any damage. However, there are some plants, most noteably, Dendrobium cuthbertsonii, that are reported to hate oil spray. Also, in my greenhouse, not long after I spray, the plants end up getting sprayed with clear water anyway, as a matter of my normal routine. So, the oil residue is rinsed off; but, by then, the mites are dead. The "dry" oil residue will readily disolve and rinse off because it has the emulsifier as part of it's make-up. If you used pharmacy bought mineral oil, not only is that grade too thick, it won't rinse off nearly as easily.

Doing a thorough spraying of your entire collection about once a month, should keep all your plants free of mites. Don't use the oil at a stronger concentration than 10 to 15 ml per litre and don't be temped to spray over and over and over too close together. Your plants need time to breathe.

 

[Stone]

Sulphur works very well on all kinds of mites - especially the microfine stuff. Probably by clogging up their breathing? But I hate the residue on the leaves too so I think I'll reserve it for dipping new plants and disinfecting plants when repotting etc. Oil works well too but I've noticed damage on some seedlings and a phrag. There are new sprays based on vegetable oils rather than mineral oil which might be worth a try. You can make your own by mixing liquid soap with veg oil. I'm sure the web has recipes. In fact I might try that myself.

 

[ALToronto]

John, thanks for the advice on horticultural oil. As for sulphur for mites, I'm just reading the product labels. Both the powder and the prepared spray are labelled fungicide/miticide. I don't know how or why it would work against mites, but Green Earth insists that it does.

I like the idea of an oil emulsion; the sulphur residue is really ugly.

 

[Paphman910]

I totally agree with John M regarding the Horticulture oil to treat for mites. All the garden shops recommend them all the time.

 

[John M]

I guess it's been a VERY long time since I actually read the label on a can of sulphur. I'd forgotten that it's a fungicide/miticide. I keep it on hand for dusting/drying open cuts on plants to prevent disease from gaining a foothold. I don't use it for active fungal infections or mites. Mike (Stone), is probably right about the fine powder clogging up the mite's breathing holes, making it a good mechanical control method. However, the residue is so ugly!

Sorry, Mike; I strongly disagree with using soap and vegetable oil on plants. Yes, some people have used it and found that it works. But, many people have also used it and found that they just did great harm to their collection. I was one of them about 30 years ago....totally devastated my collection with a soap, vegetable oil and water spray recommended by another grower. Soap is phytotoxic. No soap is safe to use on your plants unless it was specifically formulated for use on plants. Also, vegetable oil is too thick. It will clog the stomata and suffocate the plant, turning the foliage black. Plus, it does not have an emulsifier, making it necessary to use liquid soap. This is an old-fashioned, home remedy and it's simply not as good, or as safe, as using the right stuff.

 

[Stone]

Sorry, Mike; I strongly disagree with using soap and vegetable oil on plants. Yes, some people have used it and found that it works. But, many people have also used it and found that they just did great harm to their collection. I was one of them about 30 years ago....totally devastated my collection with a soap, vegetable oil and water spray recommended by another grower. Soap is phytotoxic. No soap is safe to use on your plants unless it was specifically formulated for use on plants. Also, vegetable oil is too thick. It will clog the stomata and suffocate the plant, turning the foliage black. Plus, it does not have an emulsifier, making it necessary to use liquid soap. This is an old-fashioned, home remedy and it's simply not as good, or as safe, as using the right stuff.[/

Ok John, on your advice I will avoid it like the plague! Thanks for the heads up.
This is the commercial stuff I mentioned:
http://ecoorganicgarden.com.au/products/pest-disease/eco-oil/

 

[Ozpaph]

Ive used eco-oil. In fact last weekend. No harm even in our hot weather (late afternoon application). Not sure if its works, yet.

 

[Ray]

I have to disagree with John's broad assessment of the use of soaps on plants.

I have used liquid dish-washing soaps and detergents for years with absolutely no negative results - including when used with vegetable oils.

Our differences of experience could be related to the soaps used, the concentrations used, or the timing- or conditions of application.

 

[John M]

Our differences of experience could be related to the soaps used, the concentrations used, or the timing- or conditions of application.

Making the use of soaps and vegetable oils a game of Russian Roulette. You just never know which set of specific circumstances will trigger damage and/or death. However, using horticultural oil, designed and recommended for use on plants while in growth, takes the risk away.

 

[Paph_LdyMacBeth]

I have two passion flower vines that I bring inside every winter and are notorious carriers of mites. I also happen to place these plants next to my lycastes etc which have very fine leaves and get easily destroyed by mites. I started spraying all my plants with sucrashield routinely and it eliminates mites easily. Prior to this I was using hort or neem oil, but I really didn't find it as effective and I didn't like the smell of the neem.

 

[Jaljala]

I used sucrashield with success as well on my Catasetinae.

 

[SlipperFan]

I've used sucrashield on my Phals, Paphs and Catasetinae all with good results and no harm to the plants.

 

[John M]

I've never used Sucrawshield; but, my understanding is that it's a sugar based spray. Once the solution dries, the sugar is so sticky that the bugs suffocate and die. I remember about 20 years ago when Jean-Pierre (Phrag-Plus), told me that he used Coca-Cola (as a source of sugar in solution), on his plants to kill mites and it worked really well for him.

 

[ALToronto]

I have Sucrashield - and there is a lot more to it than just sugar. I really don't like the smell, but if it works, I'll use it. I do remember getting a bad ant infestation a while back - I wonder if Sucrashield had anything to do with it?

I asked an fellow member of SOOS (our orchid society), and in her opinion, I have false mites - these are about 10x smaller than regular mites and are impossible to see without magnification. They feed on chlorophyll, and she said that she used Windex to get rid of them. Any thoughts on the 'My Big Fat Greek Wedding' remedy?

 

[Paph_LdyMacBeth]

Ha ha ha I know exactly who you talked to about the Windex! ...I'm not sure its the best suggestion, but they are excellent growers, so they might know a thing or two. I just worry about it affecting the plants as it contains ammonia and other harsh chemicals. I'm also not sure which method gets rid of the mites.
You'll have to figure out the mite lifecycle and treat accordingly. Using a combination of sucrashield weekly for 4 weeks and neem or hort oil (also once weekly a few days later) should probably do it.

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