# Preventing Rot



## Justin (Jan 17, 2011)

I've been having trouble with rot spreading thru my collection, mostly from seedlings packed in trays getting splashed with water. So far I haven't lost any plants but some are definitely worse for the wear with leaves cut, cinnamon everywhere, etc. it's a real mess.

I am trying to prevent more rot spreading, so am looking for ideas on how to keep my plants clean. I sprayed yesterday with a mix of rubbing alcohol, dish liquid, and water--and that resulted in some burns and more leaves lost--grrrr!! 

Any tips on sprays or other ways to keep plants clean for tender paph seedlings?


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## Erythrone (Jan 17, 2011)

Some tricks that work for me:

Strong ventilation (maybe a small fan near your trays will help)

Pay attention to relative humidity at night. 

Of course... watering in the morning...

Remove all the diseased leaves as soon as possible (and I don't let the container full of diseased leaves in the room)

when I have problem with rot I now use cinnamon extract (with alcool of hot water). But I agree with you. Alcool can burn.


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## TyroneGenade (Jan 17, 2011)

This has worked for me:

1 teaspoon of cinnamon powder in a coffee mug. Add boiling water and allow to cool. Carefully transfer the cinnamon stained water to a spray bottle without transferring any of the cinnamon powder (this can be a trick but a coffee filter should do the trick). Use this to spray the plants. It has saved several Paph roebelenii seedlings so far and a compot of Den. Hilda Poxon and Catt jenmanii seedlings.

You can , of course scale up and I think a 50% dilution is still effective.


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## Dido (Jan 17, 2011)

Hy I have sometimes problems on some plants too. 
But mostly have cold growing ones like Cyps. 
Till now a lot of in europe used bayleton it is a systemic fungizid. 
No it is not longer availabel in Europe, was not really good money for the bayer Company, but you still get it in US I have seen. 
Use at the Moment ( hope mostly I dont need it) It is from the compny compo and is called Duaxo.
Tried it on a Hybrid of Paphiopedilum it still lives. 
But need test on your seedlings before. 
But with Bayleton never had problems at my cold hardy plants. Dip all new plants wich are not fully yellow or fresh roots as a prvention when I get them.


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## Ernie (Jan 17, 2011)

If cinnamon and improved culture don't fix, I like Physan (quaternary ammonium salts) then Cleary's 3336 systemic.


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## chrismende (Jan 17, 2011)

I second what Ernie said re Physan. I don't know what the Cleary's is, though, and will now look it up!


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## Shiva (Jan 17, 2011)

I use good ventilation and I water the pots individually. Then I make sure the centre of the plants are free of standing water. In case of trouble, I go with cinnamon and if all else fails, I use Physan.


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## likespaphs (Jan 17, 2011)

anyone ever tried any of the Actinovate products?


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## Brian Monk (Jan 17, 2011)

For the cheap DIYs amongst us, typical pool algecide is identical to Physan, but a much stronger concentration.


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## Leo Schordje (Jan 17, 2011)

Justin, there is a lot of good advice above, so I really don't have anything completely new to offer, except emphasis. The best way to avoid fungus is to improve the growing environment.

*FANS*, soft thin leaves should be gently moving in the breeze, 24 hours a day. This gets air down into the potting mix and helps the roots. You want to feel the air moving. 

Good second step is cleanliness, remove all old dead organic matter. Empty old pots that may have once held plants, no dead leaves lying around. 

One inexpensive topical sterilant that will help with fungi and bacteria is hybdrogen peroxide at the concentration that is safe for human use on cuts and as a mouth wash. That is 3% concentration from the local grocery store in the section where first aid supplies are sold. It is safe to use as is, both as a spray, or as a drench on your orchids. Its action is only on the surfaces contacted, but there is no damage to healthy leaf tissue. Short action, when the fizzing stops and the plants dry it is gone. It is particularly effective on bacteria, but only bacteria on the tissue surfaces the peroxide touches. Cheap and easy to use for small collections, if you have a lot of plants, it is cheaper to go with other alternatives, but for just a few plants, hydrogen peroxide is cheap and easy to get locally. Safe enough to use "as is" on seedlings coming out of flask. There are commercial grades of stabilized peroxide, one is Zertol (? spelling?) it is more concentrated than over the counter peroxide. It was originally marketed for algae control in swimming pools, plumbing, greenhouse glazing and for cleaning work or lab surfaces. One would need to do the homework to figure out the dose rates. 

As mentioned earlier, Physan is another good topical sterilant. 

If your rot is slow, taking 5 days or longer to move through a leaf, there is a good chance the disease agent is actually one of the bacterial rots. These bacterial rots usually can not be stopped by a fungicide. Since fungicides can be quite expensive, this distinction is worth noting. 

Once when I thought I had a bacterial rot, I tried the anti-biotics sold in the aquarium trade for tropical fish, but to no effect. Tried both gram negative and gram positive. The plants died anyway. 

Good air movement, watering in the morning, so the leaves are dry by nightfall, clean growing area, good air voids in the potting mix so the roots can breathe, not drying out plants hard between watering so root tips don't die and provide an entry for pathogens are all key to avoiding rots. The best cures are environmental. 

Actually drying plants out too hard between watering, especially Paphs and Phrags can lead to a host of problems, that are the result of the entry of pathogens into the plants from root tips and leaf tissue damaged by drying out too hard. This turned out to be the main cause of my episode with rots back in the day when I thought I knew how to grow orchids. :evil: 

Hope this helps.


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## Justin (Jan 18, 2011)

Thanks so much everyone for the great responses!

I think i erred on all counts this time...my growing space is inside the house under lights..and we had the humidifier really cranked up this winter so night-time humidity was really high...also turned off the big fan we have running in the summer, also over-watered a lot due to travel schedule over the holidays. and finally i have to admit right now my growing area is definitely a mess.

Not to mention my R/O filter finally wore out so my plants have been getting harder water than they are used to for the past couple months...i got a replacement filter have to change that ASAP!

Anyway, I'll get the cutlure back where it needs to be. I appreciate the tips above, I need to do better with all those!


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## Erythrone (Jan 18, 2011)

likespaphs said:


> anyone ever tried any of the Actinovate products?



Interesting question.... I am interested by biological control too..


I never used that bio fungicide. I don't know if it can be efficient against fungi in our slippers, but it can't be efficient if we have bacterial rot, since bacteria an fungi are very different from each other. Actinovate is specific to some fungi.


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## Howzat (Jan 28, 2011)

I sent a couple of infected leaves (Brown wettish from the base leaf) to a lab and the verdict was : fusarium infection. I tried cinnamon for the little one without success. For thr big plants, I remove all infected leaves and then immerse in chlorine 20-40ml of 14% Chlorine in 8litres of water. I leaf it for several hours. THe plants are OK with this mix, and sometime they come good. I have tried with different fungicide (metalaxyl) and others even immersing them for hours. They still died. But this chlorine mix is the one so far saved some of my plants (NOT all)


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## Rick (Jan 28, 2011)

I'm kind of in Leo's camp.

I start all my recently deflasked seedlings indoors. In a pretty controlled environment. I have a humidifier and lots of air flow. I try to keep the humidity up around 60-70% all the time. Since its in the house, the temp rarely falls below 65F, and the high end rarely goes above the mid 80's.

Rots seem to be restricted to the runts of the flask, so I rarely put that much effort into salvaging that last 10%. 

I use RO water as the base of irrigation, but over the last couple of years, I've been working more on nutrition, and since switching over to about 10% well water with the RO, and periodically spiking with Epsom salts, my rot problems (especially with older plants) has gone down dramatically.

For those stubborn cases on bigger plants I use Dragons Blood /Cinnamon combination's.


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## Howzat (Jan 28, 2011)

Other treatment that I tried is Terrazole (active ingredient etridiazole), Ridomil (active ingredient Metalaxyl plus Mancozeb) and Kocide (copper based). Once the fusarium get hold on to your plants with say 3-4 leaves infected, only taking the leaves out then immerse in the fungicide or Kocide (fungcide/bacteriacide). Don't spray as the desease is inside the leaf eminating from the crown. If the crown is already infected, then say goodbye. People do not like to use Kocide because of the blue spots it leaves on the leaves. But for immersion it is OK. But immersion with Ridomil does not help at all, this one is good for external infection like rust etc.. My experience is that once infected with fusarium, 80% of the plants cannot be helped even with long period of immersion


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## Justin (Jan 28, 2011)

Thanks again, Leo, Rick, and all. 

I cleaned out the growing area and increased air circulation... plants are looking a lot better.

Also replaced the R/O filter so am back to pure water. Rick, I agree about epsom salts, I have been using 1 tbsp/gal per month for the last few years.

Great information in this thread, thanks Howzat!


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## Erythrone (Jan 31, 2011)

Can someone tell me more about Dragon's blood and where to buy that product?


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## NYEric (Jan 31, 2011)

Plants/Orchids Gone Wild, online. I have to order some more and if you can wait till March I'll bring a bottle or 2 to Montreal!


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## Ray (Feb 1, 2011)

I am in the "Leo camp" as well, but you know me - must experiment.

I read about a large-scale grower who added a small amount of Physan to his RO tank and used it for all watering, and reported a huge reduction in rots, and no botrytis spotting in his phals at all.

Not knowing how to keep an ever-draining-and-refilling tank accurately dosed, I decided to add Physan to my fertilizer concentrate tank instead. I added one ounce per gallon, which means my irrigation water is more like 0.01 ounce per gallon. I have been doing this for about 9 months now, and have seen a definite slowing in the growth of algae (I do have a lot in S/H culture), and I see no ill effects with the plants. I cannot say if such a dosage rate has any impact on rots, as I normally don't see much anyway.


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## Justin (Feb 1, 2011)

has anyone had trouble with physan under lights? my last spray with detergent & rubbing alcohol burned the heck out of a couple plants when i put them back under the lights...i love when that happens to sanderianums that grow 2 leaves per year...


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## Erythrone (Feb 1, 2011)

NYEric said:


> Plants/Orchids Gone Wild, online. I have to order some more and if you can wait till March I'll bring a bottle or 2 to Montreal!



Great.... I will take 1 or 2!! I want to try it.


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## Ricky (Feb 1, 2011)

Justin said:


> has anyone had trouble with physan under lights? my last spray with detergent & rubbing alcohol burned the heck out of a couple plants when i put them back under the lights...i love when that happens to sanderianums that grow 2 leaves per year...



It is always a good idea to put the plants under lower light for some days when using a product on the leaves.


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## John M (Feb 3, 2011)

Justin said:


> has anyone had trouble with physan under lights? my last spray with detergent & rubbing alcohol burned the heck out of a couple plants when i put them back under the lights...i love when that happens to sanderianums that grow 2 leaves per year...



Detergent and soaps are phytotoxic and alcohol burns tender tissue. The issue is with these two ingredients, not the Physan.

I use a constant low dose of Physan in my water (1 ml per 50 litres), 100% of the time, including the fertilizer water. Without it, I have lots of rot problems. With it, I seldom have any rot problems.


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## Justin (Feb 3, 2011)

John M said:


> Detergent and soaps are phytotoxic and alcohol burns tender tissue. The issue is with these two ingredients, not the Physan.
> 
> I use a constant low dose of Physan in my water (1 ml per 50 litres), 100% of the time, including the fertilizer water. Without it, I have lots of rot problems. With it, I seldom have any rot problems.



yeah now i know, after having to hack a nice new leaf off of a very expensive paph division as well as two of my sanderianums. thanks again for all the info contributed here.


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