Preventative routine spraying or not???

[mooch]

Hi, just wondering what the deal is with fungicide spraying. Should you spray as a preventative or just when you see things going on. I envy pics of flawless phal leaves and wish mine look like that. I don't have many disease issue's since increasing my air flow with a couple of fans, but I get occasional spotting on some leave which drives me nuts.
Anyhow, can anyone recommend some general fungicides which work and some proven routines for spraying. Thanks.

[digitalgate]

I stay in the tropics so 2 fungicide a week is crucial . Since your area has lower humidity than mine , I guess you can do with , once a week . Carptan and thiram is a good starter fungicide adding mancozeb is a great idea . However don't spray more than 4 time a year for mancozeb , fungus get resistance fast. Rotate your fungicides would be a good idea .

[pikkumyy]

i would direct this question to the phal 'experts' like fred and Ron, fred im guessing lives in tassie (because he referes to the mainland and just subtle things about tas) and ron on the south coast of aus, i class them as the two or two of, the phal experts, i dont think there is anything they wouldn't know or be able to find out for you,

personally i prefer a preventative spray because then the plants can't get sick in the first place, i just mix it in with the fertilizer once a month and give them all a spray, i'll try remember to check the name's tomorrow

[sunshine]

I do constant vigilance and treat only when needed. I also rotate my insecticidal sprays

Orchids are like children. If one get's it they all get it

[Hummer344]

I agree with Sunshine. To much treating will just lead to other problems such as disease resistant fungii and molds

[syndywindy]

I watch and treat when needed. Liken it to someone taking antibiotics when they aren't needed. Eventually you become resistant to that antibiotic and when you really need it, it won't do what it's supposed to.

[mooch]

Thanks for your replies, what are you using, what works well.

[-k-]

Physan works well, but I agree with the others and do not treat unless needed, I don't like spraying chemicals of any sorts, especially plants I keep indoors... And I always try cinnimon first, then bust out the big guns.

[pikkumyy]

i was also told to alternate between two different fungicides and pesticides so that, as the others said, you don't have nasties building up an immunity

I alternate physan and captan on my vandas, but I don't get fungus on my phals, I just wash their leaves with dishwater soap and a sponge, to make it clean, shiny and smooth. The best stuff ever is sprayed on their leaves when I see flies landing on them. The open kitchen window let's flies in even if I am on the seventh floor...I got this ponytail palm and with it was that white mite that forms fungus...when I first saw it...it got sprayed with the best stuff ever and after a couple of weeks it was all gone...I didn't even repot

[pedidiva]

Some of the "spots" may be normal pigmentation. I don't use preventative spraying. I spray when needed.

Perhaps you could show us a picture of your spots.

Pedi

[katrina]

Even alternating product use can cause immunity/resistance after a period of time. Best not to spray unless needed.

[JLu]

Fungicides are all prophylactic products. They kill germinating spores before they can enter the plant. You cannot kill the mycelium in the leaf (but you can kill any spores it produces to prevent spread). It must grow out, the leaf die, or be cut out. That said it is not necessary to spray fungicides continuously. The old Blue Mold Tobacco Network used to inform farmers when fungus diseases would be present so they could begin spraying in advance. A fungus on tobacco leaf drastically reduces the value, but the cost of the sprays is too high to do it when not required.

Fungi have a lot in common with each other (and a lot not common, too, particularly their sexual habits and asexual reproduction). They prefer the same temperatures we do and are most active around 70 F. Below 60 and above 90 there is very little chance of spore germination. They usually require wet foliage for long periods in order to successfully germinate and enter the plant. Long time means something in excess of 6 or 8 hours. That's why everyone recommends watering plants in the morning so the foliage can dry before dark. That's true of potted plants and outdoor plants. Watering in the late day or early evening is an invitation to disaster, but if you do it you definitely need to do fungicidal treatments. If you keep foliage dry you will never have a fungal infection.

Unfortunately, fungicides are way too complicated to explain here. There are contact ones that don't last and very expensive translaminar ones that do last and work great but are prone to resistance buildup much more so than insecticides. The expensive ones are by far the best and should be used mixed with the contact ones to help prevent resistance. Anyone using fungicides needs to go read a lot of information because they are far more complex than insecticides. One good combination is the turf product called Heritage mixed with contact Mancozeb. Mancozeb is cheap (about $25 / lb). Heritage is $400/ pound and is not packaged in smaller quantities.

The fungicide, Tebuconazole, in the Bayer advanced products is pretty good , available, and relatively cheap. It is one of the complex ones and should be mixed with Mancozeb also if you use it often.

The key to fungal infection is not to get it by keeping foliage dry. These diseases are devastating. The soybean fungus introduced to the US a few years ago can defoliate a field in days. Agricultural coffee growing was run completely out of SE Asia (it's native habitant) by a native fungus. That fungus is now in South America and it's impossible to grow coffee without extensive use of fungicides. Keep your stuff dry. Wheat Rust is deadly to the wheat crop. Each year plant pathologists plant test fields to guess which race of the fungus will strike that year and recommend to farmers which resistant wheat strain to plant that crop year. If they are wrong one time, it could result on worldwide famine. Fungi are bad guys. It isn't going to be the meek who inherit the earth, but fungi.

Insecticides are much easier to understand. You can wait to use them when you get an insect, but you must use good ones and ones designed for the pest you have.

[11Orchid126]

It's easy to say spray only when necessary if we live in climates like Texas, Manhattan, or New Jersey which have bouyant, reasonably humid air. Living in Australia and Singapore pose entirely different conditions and therefore require different measures.

[koshki]

JLu, thanks for taking the time to post that very helpful information.

[mooch]

Thanks JLu, very informative.
I actually work in the turf industry and have heritage and mancozeb here on the shelf. My confusion comes I suppose a little from work because we have a routine spray program to prevent disease, in which we alternate fungicides often to prevent resistance.
I don't really want to spray so I will try everything else to prevent fungal attack. Prevention is better than cure.

[Anton]

Most certainly. I use it once a month with a combination of anti fungal, anti pest mixed in with my usual feeding regime.

When the GH is closed up for winter, I sometimes use the anti fungal a bit more often if the humidity has been a bit high and I see some early signs on some leaves.

[katrina]

Originally Posted by 11Orchid126

It's easy to say spray only when necessary if we live in climates like Texas, Manhattan, or New Jersey which have bouyant, reasonably humid air. Living in Australia and Singapore pose entirely different conditions and therefore require different measures.

The fact of the matter is...the more you spray...the more you're going to have to spray. No matter where you live. I'm not against using something when it's called for but again...the constant over-use of many of these chemicals is what has and will (as long as people do it) continue to cause problems.

An ounce of prevention....

[pikkumyy]

Originally Posted by mooch

Prevention is better than cure.

thats the phrase i was trying to find, honestly, the fungicides and pesticides for my orchids is the only chemicals i use in my entire garden (you should be impressed i live on 5 acres), all other problems i try tackle by making the plants healthier and more resistant to attack, and the chooks do their fair share of keeping nasties under control,
with prevention being better than cure, by prevention i don't mean to entirely depend on sprays, i mean to make the plants as healthy as possible, and use the 'cides as an extra defence

Originally Posted by Anton

Most certainly. I use it once a month with a combination of anti fungal, anti pest mixed in with my usual feeding regime.

hmmmm, i wonder where i may have heard that before

[Anton]

Originally Posted by pikkumyy

hmmmm, i wonder where i may have heard that before

Hmmm, yes .......... I wonder ............

[JLu]

mooch, I understand what you are saying about routine treatment of turf. I'm not so sure it's a good thing, but I'm not chemophobic either. That probably wouldn't be the best trait for a chemical engineer and I'm into awarded orchids so I have no desire for ugly foliage. Even though foliage isn't part of the issue with flower quality awards, it is part of the overall impression and it is part of cultural awards.

There are a several reasons for routine turf treatment. One you can't control when Mother Nature wets the grass and keeps it wet for long periods. Two, some of the most desirable lawn grasses are very prone to fungal diseases, three some people are obsessive about the appearance of their lawns (like I am about the appearance of my orchids, so who am I to criticize), four once you have a fungus you're stuck with damage it did for the season (see previous point), and five, to some extent it's in the best interest of lawn service companies to sell service contracts and to see that they keep them in effect by not having appearance problems. I have no problem with any of that.

My only point was that if your orchids are protected from rain (and not everyone's are) then you are in control and should be able to keep foliage dry and avoid the need for fungicides which are really more complicated to select and use than most people will ever understand. I have no problem with fungicides either, but the good ones are very expensive and I'd like to keep some money to buy more Apple gadgets and GH propane on which I spend a dad blame fortune. Propane costs me about $4000 a winter with about $1000 in each Jan and Feb. So if I can avoid some $400 a pound fungicide then I can buy some $400 a pound miticide. What a rat race!! Why do I do this? Why does anybody?

[jannypan]

However don't spray more than 4 time a year for mancozeb , fungus get resistance fast.

[JLu]

"However don't spray more than 4 time a year for mancozeb , fungus get resistance fast."

Not to Mancozeb or other contact killers, only to the designer products that interfere with particular biological pathways. Mancozeb is like hitting something with a hammer. You never get immunity to that.

Insects can become immune to designer insecticides, but never to horticultural oils that smother them. Same deal. You can become immune to measles, but not to being killed by being hit by a train.

That is the exact reason that the exotic (and very effective) targeted products should always be mixed with a contact killer that wipes out the bulk of the population so that the few that could become immune to the designer product will have a lower statistical chance to survive and breed. That is not some screwball opinion of mine. It's standard -cide science.

[Anton]

I use 3 different fungicides and a similar number of insecticides at different times so that they don't form a resistance.

Like everything in life, use in moderation to get best results.

[mooch]

Anton, would you mind giving me the names of the products you use?
Your conditions will be similar to mine.
Thanks.

[digitalgate]

Originally Posted by JLu

Insects can become immune to designer insecticides, but never to horticultural oils that smother them. Same deal. You can become immune to measles, but not to being killed by being hit by a train.

resistance can be managed. If one is uncomfortable with using fungicides then don't use it. But you have to control your micro climate of your plant. If you like me can't control the micro climate . Then fungicides is the only way to manage the plant. That just my 1 cent worth of ideas.

Oh, there was a research papers being done mentioning side effect of overly reliance on mancozeb. So relies on one fungicides is not a wise thing to do. Rotate make sense.

[Ray]

I agree with JLu in this arena. I won't claim to know the killing mechanism of all the available chemicals, but generally speaking, it is the ones that disrupt biological processes, rather than do mechanical damage that can lead to the development of resistance.

Physan, for example, acts as a very aggressive "soap" to strip protective coatings. It has other action as well, but that is the primary one.

Likewise, a product like Zero-Tol - a peroxyacetic acid-stabilized hydrogen peroxide product (and my new favorite for keeping algae out the the greenhouse and s/h pots) - "burns" (oxidizes) the pathogens to death.

Another mechanical mode exists in a product called Oleotrol-M, which I sell a great deal to wineries, as it is effective on mildew. Consisting of nanoparticles of vegetable oil, it uses the reduction in surface energy to disrupt cell walls. Think of putting a drop of oil on water: it immediately forms a thin film on the surface - reducing the surface energy. When that "nano-drop" of vegetable oil hits the cell walls of a pathogen, the force is sufficient to disrupt it, allowing the cell to collapse and die.