Rotted new growths on cymbidiums

[orchidgiants]

We have been growing about 10 cymbidium plants for about the past 8 years and have never had a problem with rotting new growths. We now have a plant that has rotting new growths. Just pulled out the 2nd one tonight and took some pictures. We grow outside in the back yard in California, and treat them with Bayer AllInOne Rose Care to keep the scale under control. We water with the hose.

We got this plant about 5 months ago from the Opportunity Table of plants provided by the speaker at our local Cymbidium group meeting. It's an unbloomed plant of a new cross he made. It had 2 visible new growths at the time, and the speaker told us to repot it when we got home, which we did, into a sterilized pot. We discovered a 3rd new growth during the repotting. It's been growing well for last past few months, but just recently two of the new growths rotted.

From what I've found on the internet, it looks like this rot is caused by a bacterial or fungal infection, and is possibly related to over-watering. Any idea if we should be treating it with some other chemicals, taking it out of the pot and checking the roots, or is just pulling out the rotted growth and hoping for the best all we can do? We really want to bloom this one to see how the flowers turn out.

This is a picture of the rotted new growth that we pulled out:


Here is a picture of the place in the plant where we pulled it out from:

Thanks.

[Zoi2]

Welcome to the Orchid Board.
I would probably check the roots and treat with some hydrogen peroxide or other antiseptic.
Somebody with more experience with cyms will chime in pretty soon.
Joann

[orchids3]

It looks like a Bacterial rot alright - maybe fusarian wilt which works from the inside - Some people heat a hot piece of iron and scorch the cut when the take away the rotten bulb, spray the cut with tree pruning seal or sprinkle cinnamon on the wound. A hot cutting tool also works.
I had some rotten leaves after using "Bayer All in one" and only used it on a few plants to see the effect. I think we need to know what the fertilizer component of the "All in One" . I did use the Bayer "Tree and Shrub" but stopped after Bayer started to add fertilizer to that one too.

[Des]

Try to find a fertilizer with a lower nitrogen content. Also most of these fungal and bacterial infections are water bourn so sterilize your feed water with hydrogen peroxide . Also give the whole growing environment plants and all a good wash down with a good contact fungicide at two week intervals for a few months not forgetting to use a wetting agent
Welcome to the OB

[PitcherASAMD]

Originally Posted by Des

Try to find a fertilizer with a lower nitrogen content. Also most of these fungal and bacterial infections are water bourn so sterilize your feed water with hydrogen peroxide . Also give the whole growing environment plants and all a good wash down with a good contact fungicide at two week intervals for a few months not forgetting to use a wetting agent
Welcome to the OB

the whole sterilizing water with hydrogen peroxide is such a great idea! how much hydrogen peroxide would you use per gallon?
Thnx - Katie

[Des]

Originally Posted by PitcherASAMD

the whole sterilizing water with hydrogen peroxide is such a great idea! how much hydrogen peroxide would you use per gallon?
Thnx - Katie

I use 14 mls of 50% H2O2 to 200 liters of feed water and leave to stand overnight. Something I also do in the winter is to warm the feed water with an aquarium heater
as plants that are watered with icy cold water go into shock and are more susceptible to infections. However this might not be necessary in your part of the world .
What Cymbidiums do you have in your collection ?

[PitcherASAMD]

Originally Posted by Des

I use 14 mls of 50% H2O2 to 200 liters of feed water and leave to stand overnight. Something I also do in the winter is to warm the feed water with an aquarium heater
as plants that are watered with icy cold water go into shock and are more susceptible to infections. However this might not be necessary in your part of the world .
What Cymbidiums do you have in your collection ?

I actually don't have any -- Just thought your idea was super smart!

[orchidgiants]

Thanks for all the responses and greetings!

I've picked up a few pieces of bark and can see healthy roots heading down into the bark, so I think I will not take it out of the pot just yet.

The Bayer All In One does have a fertilizer in it - it is 9-14-9. We only use that once every 6 - 8 weeks, and we find it controls scale, which we have in the yard environment, but has not harmed any plants that we know of. We use it on indoor masdevalias as well to control mealy bugs that pop up every so often. But now that you mention it, we've had some rotted new growths on one masdevalia too, so maybe there is a connection to the Bayer!?!? On the other hand, we're new to masdevalia's and still figuring out how to care for them, so it could be us. Or it could be that the Bayer affects new growths on plants that are overall still young (as opposed to new growths on older, well-established plants). As far as we know, it has not harmed any of our other cyms that we use it on.

During this growing season, we've been feeding the cyms with GrowMore brand 30-10-10, half the recommended strength, every 2 out of 3 waterings. When it is very hot, we lightly water the cyms once or twice during the week as well (extra waterings with plain water). Des - Why would we want to feed it with a lower nitrogen fertilizer now, during the grow season? (We have 20-20-20, Urea free 20-10-20, and Schultz 19-31-17 in the cabinet for other uses, but we've been using the 30-10-10 just during the active grow season on the cyms for a few years now).

We've never used hydrogen peroxide in the water, but may give it a try. Des - can you recommend a good contact fungicide? We thought the Bayer would take care of most bacterial and fungal infections systemically, but perhaps we should switch to a contact fungicide instead.

Whenever we do "surgery" on one of our plants, we dust the wound with sulfur. Orchids3 - Is the cinnamon recommendation doing basically the same thing?

We have:
Cymbidium (Dag 'Lollipop' 4n x Wakakusa 'Pearl' 4n) 'Stirling'
Cymbidium Ivy Fung 'Portwine'
Cymbidium Point Conception
Cymbidium Wallguard 'Alice'
Cymbidium (Lemon Butter x Golden Elf)
and 5 or 6 unknowns that we've picked up here and there.