Physan 20 help.

[Cattleya17]

Hello! I finally got my hands on two bottles of physan20 and I used it for the first time today. A couple of my plants have shown signs of a leaf rot one seedling phal crown rot and a cattleya and a laelia with leaf rot.

I put the plants out and we had alot of rain here in NY recently and then we had a major cold snap like frost and even snow flurries in a couple if places. I bought the plants in early enough I thought but today I noticed the diseases.

So I mixed two teaspoons of physan20 per gallon and sprayed all of my plants twice (after removing damaged tissue) I sprayed them all because I just want to be safe and I sprayed down the growing area as well. Was this the right move? Mixture? Also how frequently should I spray them?

Also it started off looking like just sunburn. The whole leaf turned purple on the one cattleya then after I bought them inside for the cold snap it faded to only two black spots with a clearish ring around them and they were weeping. Any ideas on what's infected them?

[Discus]

Sounds like bacterial or fungal infection; it's hard to be sure, and it's not that unusual to be both.

If you're spraying with something wet, it's usually a good idea to do it early in the day so it dries off before the cool of night.

AFAIK quaternary ammonium formulations like Physan only work while in solution, so once dry, it has no effect - so you don't want the plant to dry off tooo quickly either.

You can try some cinnamon powder on the weeping sores, but I generally chop any leaves like that off, pronto.

[Jayfar]

I keep physan 20 around for sanitizing things, but when I see bad things happening I tend to reach for the Phyton 27, since it is a systemic and can eradicate bacteria that may have already spread within the plant. Use due caution in handling Phyton, including wearing rubber gloves while mixing it with water and turning off fans while spraying.

And as Discus said, cut away infected parts.

[Bud]

' we had a major cold snap like frost '
=this did it...
your plants was exposed to frost, small wonder it didn't turn to liquid ....
all the characteristics you mentioned indicated frostbitten leaves....the cells break down and turns deep purple when frozen= when defrosted indoors it turned black.

[Cattleya17]

No bud I'm sorry I misled you. I was describing how cold it got during the cold snap the plants came in well before that. The lowest temps they encountered is 44 the last night they were out.

I cut off everything that looked suspicious I can spray with this regularly for a preventative right?

[Bud]

physan 20 is a disinfectant....I remember someone here who sprays weekly just to rule out fungi and bacteria infestation....
44F at night outdoors is not dangerous but anything below 50F for long period can affect some orchids....its going to be warmer after Memorial day so its going to be nice for the orchids outdoors....your area is tricky; I remember you had a freak snowstorm in June of 2004

[Cattleya17]

Weekly spraying a it is then! Our weather is freaky! I'm gonna try to find the phyton27 it couldn't hurt. I just don't wanna lose most of my collection to rot again! Summer2011 my entire phal collection 14 plants including one ive had since I started getting the hang of orchid growing were lost to rot and I had nothing to stop it l...... So not this time!

[Ray]

I would not spray that frequently at that concentration. 2 teaspoons per gallon is a good level to fight a surface infestation (Physan is topical, not systemic, which is why cutting off all damaged tissue is a good idea), but as a preventive, I'd use no more than a teaspoon per gallon monthly.

[Cattleya17]

Ok good to know! Thanks for all of the help!