Yellowing Leaves - Orchid Board

scy · #1 07-10-2011, 05:05 PM

I noticed some change in my cymbidium chen's ruby from last week. I am treating this orchid with malathion and a systemic, switching sprays each week, so it does not get used to the same spray. It does not seem the malathion is doing much other than drawing them out to the surface and I have backaches from cleaning each individual leaf. I think I will just stick with the systemic going forward.

For the past 2 weeks, I started to put it outside on the deck (east facing) in the morning hours only for more sunlight. Normally it sits by a deck door. Outside, the temperatures are 80s-90s, med humidity, dappled sunlight around 9 am but full sun from 10 am onwards. I bring it back inside at noon. I noticed that the leaves are not medium lush green as they were but started to turn light green, which I thought was ideal for cymbidiums. I noticed these brown spots on the leaves that weren't there last week. I cut them from the leaf. They were located in the middle of the leaf (lengthwise). Is this a result of sunburn?

The 2nd photo shows a few leaves yellowing. While I have removed 3 yellow leaves from May - June, I noticed there are 3 more yellowing leaves now. I did not panic too much before, because the original leaves were in the center, leading me to believe it was just from old growth. However, one of the leaves are from new growth while the other 2 are from the center. Also the yellowing progression is different from each other. One shows yellowing straight down the middle while the sides are green, while the left one is green at the base, then alternates between yellow and green along the leaf. Is this a result of scale or something else?

I have left it inside this week after noticing the changes. Also the photos are not accurate in terms of leaf color. I took them quickly on my phone and they are much lighter in person (med - light green). Thank you for your help!

Susan

Otis226 · #2 07-10-2011, 05:11 PM

Hi, I don't grow cymbidiums, but if I saw that on one of my catts, I would say its sunburn.
Best,
Tony

scy · #3 07-10-2011, 05:14 PM

Which one is sunburn? The brown spots, yellowing leaves or both? Would the way the leaves are yellowing make a difference in figuring out why it's yellowing?

Kelo · #4 07-10-2011, 05:49 PM

The yellowing could just be old leaves dying off. As for the brown spot that could be burn but I don't think it is. Are the yellowing leaves on an old pseudobulb?

Eyebabe · #5 07-10-2011, 06:07 PM

I don't grow cymbidiums either but have killed two

The leaves should not be dying off so fast; I would be concerned about the roots.
The brown spots look fungal to me...

scy · #6 07-10-2011, 06:51 PM

Quote:

Originally Posted by Kelo

The yellowing could just be old leaves dying off. As for the brown spot that could be burn but I don't think it is. Are the yellowing leaves on an old pseudobulb?

The ones that fell off in the past were in the center, which were older bulbs. As for the new ones, two are from the center-ish (separate bulbs) and one (in the background), is definitely from new growth. Since I'm losing about 6 leaves since May, I can't help but be concerned, especially since one of them is from new growth.

scy · #7 07-10-2011, 09:23 PM

Quote:

Originally Posted by Eyebabe

I don't grow cymbidiums either but have killed two

The leaves should not be dying off so fast; I would be concerned about the roots.
The brown spots look fungal to me...

Hmm... I looked at the link in the "Pests & Diseases" section. I have some of those and I have new photos that I'm not sure about.

1. Center Yellowing with Green Sides: Just like the last photo under Bacterial Soft & Brown Rot (Erwinia) in that link. I am pretty sure I caused this when I mist in the morning. I noticed a while back that the bulbs looked shriveled and leaves starting to crinkle. I was afraid of overwatering and thought misting would be enough until I had more time on the weekends to water. To treat, it says to remove the infected leaf and to spray with bactericide like Physan. Would I have to worry about the same problem if I spray again even with Physan or is it ok?

2. Brown spot: Not sure what that is.

3. Black Spot on Yellowing Leaf: On a different cymbidium, I noticed 2 of these spots on tip of one leaf. It looks just like the 3rd photo under Bacterial Brown spot. I increased air flow with a tiny fan I put by the windowsill for increased air movement. I removed that section and hope it will be enough.

4. Black line going down middle of leaf: No idea what this is. Will it gradually turn into #1?

5. Yellow Leaf on New Growth: This is a close-up of the new growth that's turned yellow. My guess is this is what #1 looks like if left unchecked.

6. 3 Yellow Spots: Looks similar to the photo of Septoria symptoms. There are tiny black dots on the other side. It didn't show in the photo. Can be solved with reducing wetness on leaves and alternating between systemic & protectant fungicide.

Seems that all this has probably been a result of misting in the morning. I will stop misting, especially since I'm causing more harm than good. Can anyone give any recommendations on treatment? The website says to spray but when I read the Physan packet, it says to "remove compost from plant, then soak entire plant 10 minutes or more. Cut away all rot with treated tool. Repot in physan soaked compost. Use: 1 tablespoon physan 20 per gallon of water."

I am hesitant in unpotting it for several reasons:
a) It's in a 7" pot and very tightly packed. I have never dealt with a plant of this scale.
b) It normally blooms in August (according to seller) and do not see any active growth right now. It was recommended that I repot in September if I did not see any blooms as that is the start of the growth period.
c) I was going to attempt my 1st division to make it into a more manageable size.

Can I just spray it at the recommended dilution and hope for the best? How often should I keep up the treatment?

Additionally, I am new to growing plants in general (not just orchids) and am not having a good success rate. I just watched 2 phals die and a dendrobium just bit the dust today. My other orchids are just repotted in bark now after suffering root rot with few roots left. At this point, I'm not even hoping for blooms. I'm just hoping they'll survive. I have a couple of orchids books that I refer to for reference, but not a lot of pictures, which leads me here to ask for help in identifying problems. It seems that no matter how much I try to care for them, I wind up doing more harm than good. Sorry for the long post and my ranting. I just feel it's a matter of time before I manage to kill off the rest of my orchids.

Eyebabe · #8 07-10-2011, 09:53 PM

Erwinia can be killed with Physan which I would mix up as the instructions dictate; I'd sit the plant in it for 10-15 minutes.

Even better....take the plant into the grower who sold it to you and ask for "help".
Cymbidiums are expensive and I think it is reasonable for you to elicit their assistance.

They may also be able to help you trouble shoot the other issues you are having with your collection...

Cym Ladye · #9 07-11-2011, 01:12 PM

SCY,

Speaking from successfully growing Cymbidiums for over 40 years, take the !@#$% plant outside, put it in 50/50 sun/shade, leave it out there until frost and stop fussing with it! You have sunburn on two of the leaves, no big deal, and possible erwinia on the new growths from which you are losing leaves ...or not. Stop the morning misting and go to a once a week thorough watering with fertilizer, if you are not using slow release pellets.

If you are in fact losing the inside leaves of the new growths, the best way to treat it is to remove all the leaves from the new growth and let it start a new one. Loss of outer leaves on older bulbs is normal. Treat the bulb with cinnamon and allow it to air.

However, if you are losing a lot of leaves from the oldest bulbs, I suspect you are over-watering (probably the cause of the lack of success you mentioned with your other genera) and that the roots are rotting. Gently take the plant out of the pot and feel the roots. If they are soft or mushy, you have another far more serious problem.

In regard to using a spray fungicide on my Cyms, I cannot remember ever using one, and I show and exhibit my plants extensively. I do use a systemic insecticide when needed, but only two applications at ten day intervals. They are grown outside all year long. Small marks are to be expected in hobby growing. The leaves are not made of plastic. Your repeated use of insecticidal sprays as well as plain misting is what probably caused the new growth rot.

Most Cym problems come from coddling the plants. This is a hardy genera but it will not tolerate excess water standing in the crowns, and will not fair well when continually moved around. Stop worrying so much.

Cym Ladye