physon 20

[kindrag23]

I think my gramm. Has brown spot rot. How do I use the physon 20 to hopefully get rid of it.

[Orchid Whisperer]

Hi Kindra

My suggestion would be to first confirm that you are correctly diagnosing the problem. Search for St. Augustine Orchid Society, their website has an excellent section on pests and diseases, including pictures.

If you confirm that you have bacterial brown spot, first step is to use a sterile blade (such as an X-acto knife) and cut off affected tissue. You need to cut into healthy tissue outside of the infected area. If you have multiple infection sites, flame-sterilize your blade between cuts.

After cutting out infected tissue, then treat the plant, and nearby plants, with a bactericide like Physan 20. Isolate your infected plant from the others until you are certain the infection is gone.

Good luck!

[kindrag23]

@bud gave me the link to their website and I can pretty sure that is what it is looks like I am going to have to order it off ebay already cut diseased portion off how do I use it though?

[Orchid Whisperer]

Hi Kindra

I would recommend consulting the instructions on the package. Others here may have better advice on how to use Physan.

I have been growing orchids since 1982 and to be honest, I have never purchased a bactericide. From time to time, I have used hydrogen peroxide and rubbing alcohol (from the grocery or drug store) to wipe down leaves etc. to reduce bacterial and fungal spores on plant surfaces.

Most of my treatment for brown rot, black rot, etc. has involved cutting out bad tissue, cleaning up the plant, isolating it and hoping for the best ("best" = no spread on the plant in treatment, no spread to other plants). Sometimes I win, sometimes the pathogen wins.

I have nothing against Physan 20 or similar products, just have not invested in them personally.

[silken]

It is a liquid that you mix with water and spray on the plant as per instructions on the bottle-I forget the exact dosage but it will say. Spray the plant well and don't put into direct sun as sunburn can occur on wet leaves. The media can be doused as well. You should likely repeat in a week or two.

[naoki]

If the spot is small, you can use q tip to apply undiluted solution. Then poke holes with needles starting from surrounding region toward center. It is unlikely spraying diluted solution will stop the infection since it won't penetrate into leaves. If infection has spread, cutting the leaves is required.

[kindrag23]

The leaves have been cut and I soaked already with bayer 3 in 1 (disease mite insect)

[Ray]

Physan 20 is a topical disinfectant. Brown rots tend to be systemic, so will be unaffected by it. You need a systemic treatment of some sort.


Ray Barkalow
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[naoki]

I thought that you got bacterial infection, and not fungal infection. Bayer's 3 in 1 contains: Imidacloprid, tau-fluvalinate, Tebuconazole. The first is systemic insecticide, 2nd is miticide, and the 3rd is fungicide. So I'm not sure if it is effective to bacterial infection.

If you have cut off the leaf (I use the Physan 20 injection method to reduce the loss of entire leaf even though it makes ugly bleached dead tissue area) and if it is not spreading any more, you probably don't need to do any chemicals. Or if you feel like, you can spray and drench with 325mg aspirin/gallon water. Loosely speaking, plants use Salicylic acid to signal death of infected cells, and also the signal will raise the defense system of healthy cells around the infected region. Aspirin is a slightly modified form of SA. I'm not completely sure how effective it is, but it doesn't have any ill effect to orchids at this concentration. I use it when deflasking, after some disease, and when I get new plants (which is usually stressed due to the change of environment).

If it's spreading, as Ray suggested, you might want to try systemic bactericide. I've used Phyton 27 for this purpose. The table below list Phyton 27 as non-systemic, but their web site says it is systemic.

Here is a useful table:
http://www.staugorchidsociety.org/PD...idDiseases.pdf

[tucker85]

Physan 20 is a mild bactericide/fugicide. For routine prophylactic treatment you can use it at 1 teaspoon per gallon of water. For treating currant infections you can use it at 2 teaspoons per gallon of water. Of course you don't need to make a gallon. You can make a half gallon or a quart by using one half or one quarter the amount. You can spray is on or wipe it on. For problems in the mix you can pour it through the mix or sit the whole pot in a bucket or pan filled with the Physan solution.