My account of fusarium

[nikkik]

I purchased two vandas at a local greenhouse at the end of January. This particular greenhouse just got back from a flower and supply show in Florida. They brought back tons of orchids, which aren't readily available in Michigan. They had about 20 vandas they had just unloaded from the truck. I did my normal pest/disease check and everything looked fine with the plants. They all had great roots, pretty leaves and were in spike.

After about 2 weeks, one of the the plants had some yellowing of the roots, they would then turn brown and shrivel, but no purple when cut. I chalked this up to a new environment because they just came from sunny, warm Florida to dismal, cold Michigan, besides I didn't have any leaf loss so I wasn't worried. The older leaves (lower six) on that vanda were a slightly different shade of green then all the rest of the leaves, but I just thought it was because of light or fertilizer or something else prior to my ownership, I'm not sure if this detail has anything to do with the fusarium, but I want to be as detailed about my experience as possible.

I had gone to that greenhouse several times over the winter and noticed that their vandas had taken a turn for the worse, but when I spoke with the owner he said they really weren't watering them well. His vandas had leaves falling off in the middle of stem, not just the bottom. The roots were also shriveling and collapsing. I knew there were many possible reasons for these signs, especially because I couldn't get an up close look at the plants because they were hanging much higher then I could reach. I was slightly alarmed, but brushed it off because besides a root here and there turning yellow, my plants SEEMED fine.

The winter passed and spring came. I put my plants outside as soon as the temps were warm enough. Literally, the bigger of the two vandas declined overnight. I had tons of yellow or collapsed roots. When I cut into it I did have a very noticeable purple ring. I kept making cuts up the stem of the plant hoping for a clean cut, but I never got one.

After realizing the severity of the situation, I naturally checked the second plant I bought. And yes there absolutely was fusarium. The good news is after nearly cutting off the entire root system, I got a clean cut and for my own piece of mind, I cut above my "clean cut". I was left with two roots.

I found out that fusarium spreads through spores and thrives when the conditions are prime for it. Fusarium is especially present in spring and periods of heavy water. So initially, there may not be signs your plant has fusarium.

The second vanda has been growing new roots and leaves. I haven't had an issue and I didn't see anything noticeably wrong with the two roots that remained. Today, something kept nagging at me to cut into that plant again. When I cut into it there was fusarium in the stem where there was a root that had been previously removed AND in a spot where an old inflorescence came out of the stem. The roots below this were healthy, no fusarium. This case of fusarium started in the middle of the stem, not the bottom.

I wanted to post this thread because I have heard tons about most orchid pests and diseases. I know what to look for and how to treat most of my plants' ailments. I have personally found a lack of information on fusarium or people's experience with it in their orchid collections. What I have found in books is little to my satisfaction and on the Internet what I find has more to do with crops, annuals and grass. My hope is that someone will learn something from my experience with fusarium and catch it before it cost a plant or collection.

[Leafmite]

Did you use a systemic fungicide when you first saw the signs? These diseases tend to be everywhere, just lurking for a plant that is susceptible. Many bacterial and fungual infections are carried through the air or even by critters/insects. I see this often in non-orchids (fire blight, American chestnut blight). Not very fun. Here are some sites about orchid diseases that are helpful.

Orchid Pests, Orchid Diseases
http://www.houstonorchidsociety.org/...ySueBottom.pdf

[nikkik]

Originally Posted by Leafmite

Did you use a systemic fungicide when you first saw the signs? These diseases tend to be everywhere, just lurking for a plant that is susceptible. Many bacterial and fungual infections are carried through the air or even by critters/insects. I see this often in non-orchids (fire blight, American chestnut blight). Not very fun. Here are some sites about orchid diseases that are helpful.

Orchid Pests, Orchid Diseases
http://www.houstonorchidsociety.org/...ySueBottom.pdf

I did use a systemic once I discovered what it was, but it was already present when I purchased the plants. Fusarium needs to be cut out and it is more difficult to eliminate then other orchid pathogens.

I am very familiar with both links, but thanks for posting them for others who read this tread.

[Island Girl]

Sorry to hear about your plants. I hope it wasn't able to spread to any other part of your collection. Thanks for sharing your experience, I'm sure that it will help someone. I haven't experienced this fungus, but it does seem like a lot of ppl (from all over) have had bouts of this fungus this year... It's rather worrisome, actually...

To get rid of fusarium, do you cut it out, and treat with cleary's? (I can't remember what action to take exactly, b/c it's been a little while since I've read the info on fusarium ) and like you, I'm familiar with the links Leafmite posted, but I don't recall reading about it starting in the middle of the plant, and the tidbit about the bottom leaves on your Vanda being different in color... I would've thought the same as you did.

[nikkik]

Originally Posted by Island Girl

Sorry to hear about your plants. I hope it wasn't able to spread to any other part of your collection. Thanks for sharing your experience, I'm sure that it will help someone. I haven't experienced this fungus, but it does seem like a lot of ppl (from all over) have had bouts of this fungus this year... It's rather worrisome, actually...

To get rid of fusarium, do you cut it out, and treat with cleary's? (I can't remember what action to take exactly, b/c it's been a little while since I've read the info on fusarium ) and like you, I'm familiar with the links Leafmite posted, but I don't recall reading about it starting in the middle of the plant, and the tidbit about the bottom leaves on your Vanda being different in color... I would've thought the same as you did.

Thank you for your kind words! Luckily, these plants were always isolated from the rest of my collection. I am keeping a close watch though. I agree that fusarium is scary because the signs aren't as obvious as other pathogens.

And your spot on about how you treat it, cut until there is no more purple (each time a cut is made it should be with a sterile tool, as not to contaminate the plant again) and treat with Clearys 3336.

What prompted me to post is I've always read, including on the links above, to look for signs in the roots and withering of the leaves by the time you see all the major signs of fusarium there is a good chance your plant won't have a chance. Plus, there was fusarium at the base of the old inflorescence and stem. I never had heard this piece of information. If roots are collapsing for no reason, this is a red flag, especially if the plant is new.

[Island Girl]

That's good that you kept them separate! Just goes to show... It's always a good idea to keep new plants quarantined This is a good reminder.

[MrsSky]

Thank you for posting about your experience with fw. I recently lost some dens to fw and am trying to keep it from happening again. Our weather here has been colder and wetter this summer, I think that taking them outdoors in less than perfect conditions was the problems beginning for me.

[nikkik]

Originally Posted by MrsSky

Thank you for posting about your experience with fw. I recently lost some dens to fw and am trying to keep it from happening again. Our weather here has been colder and wetter this summer, I think that taking them outdoors in less than perfect conditions was the problems beginning for me.

I'm sorry to hear about your plants! It's always so discouraging to lose them to something like fusarium.