Nematodes...

Foliage nematodes are difficult to control in other crops. For temperate perennials such as Hosta, individual plants are dug up and soaked in near boiling water or they are typically destroyed.

I was not aware that foliage nematodes were an issue with Orchids. In the US, Pylon (very expensive) is registered for use with foliage nematodes only in a greenhouse setting...and I'm not sure if it would work on Orchids or not.

 

Here is a publication from Hawaii in 1998...potentially more of a problem than we think since it can be confused with other maladies. Although if it was real prevalent, we might have heard more about it by now. In my Wife's company, they do test their crops (temperate perennials) for foliage nematodes using microscopy. If I see any orchids in our collection that are suspect, I'll try and get some tissues samples tested.

https://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-13.pdf

 

Wow! That paper is scary!

Over the past 40+ years, I'll bet that quite a few of the "rots" or other undiagnosed maladies I've observed might have been nematodes.

 

That's what I was thinking...so when I do run into a case like that, going to see if I see wiggly worms through the microscope.

 

Interesting, thanks for the link Chuck. In retrospect, some of the orchids showed some of the symptoms described there. To detect it, it appears that you can suspend the chopped up leaves and observe under microscope. I should try it when I see a suspect.

I didn't know that there aren't so many chemical control options against nematodes. But this paper is interesting:
Jagdale, G. B., and Grewal, P. S. 2002. Identification of alternatives for the management of foliar nematodes in floriculture. Pest Man- agement Science 58:451–458.PDF link
It shows that ZeroTol is effective against Aphelenchoides spp., which is the cause of orchid infection.

There are several other papers using plant extract as nematicides. One of them showed Cannibis sativa leaves have some effects on other types of nematodes: https://www.researchgate.net/profil..._incognita/links/09e4150facb273f41c000000.pdf

 

I did the same thing.

 

Yuck!!!

 

I think my wife has a video of nematodes through a microscope...(from infected Hostas). We were at a conference last Summer where Dr. Grewel updated the 2002 paper...not sure the zerotol was as effective as originally thought. I can't find it on the web, but will see if I can get a copy.

 

Thanks, Chuck. I think this is probably it:

An, R., Karthik, N.K. and Grewal, P., 2017. Evaluation of botanical and chemical products for the control of foliar nematodes Aphelenchoides fragariae. Crop Protection, 92, pp.107-113. (ResearchGate abstract)

I'll take a look at it, too when I have time.

 

Yes Naoki, that was the research I was thinking about. Given that Orchids are so varied compared to Hostas, I wonder if the results would be anything close to the same. Hopefully, I won't have to find out . The Nema-Kill would definitely be worth an experiment since its basically non toxic to humans.

 

Rarely do nematodes numbers become large enough to cause much of a problem. It is what they bring with them, fungus, bacteria, disease, and insects, that cause the problems. Healthy plants and good media quality should be balanced with good and bad types of nematodes, it's when we get this balance out of whack, with insecticides, fumigants, and soil sterilizers, that we start to have problems with them. Nematodes are everywhere, in everything. There are benefical ones that cause harm and parasitic ones that are benefical. Good sanitation, not using old media and use of correct pesticides, and you should not have problems with nematodes. My two cents.