Black blotches on old JWP needles

tanlu

Shohin
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This afternoon I found something I've never seen before, black spots/blotches on old needles of one of my JWP. I can't imagin it being root rot, since it's in inorganic substrate and I only water when necessary. I also read that JWP are substantially more resistant to needle cast/other foliage attacking fungi, so I have no idea what this is. I naturally removed all the infected needles, but I hope this doesn't come back and spread! Pines cannot afford to be defoliated like deciduous!!

Any ideas on what this is??

T
 

Vance Wood

Lord Mugo
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This afternoon I found something I've never seen before, black spots/blotches on old needles of one of my JWP. I can't imagin it being root rot, since it's in inorganic substrate and I only water when necessary. I also read that JWP are substantially more resistant to needle cast/other foliage attacking fungi, so I have no idea what this is. I naturally removed all the infected needles, but I hope this doesn't come back and spread! Pines cannot afford to be defoliated like deciduous!!

Any ideas on what this is??

T
A picture would be helpful. And, (sorry for the preposition) the information you received about JWP being more resistant to diseases and the like; in my experience I find them more susceptible. I have to spray mine at least once a year with a fungicide or I lose all of last years needles or entire trees. I have attempted to grow hundreds of them from seed, and only have a dozen left. Most of them succumbed to some sort of fungal infection endemic to my environment. I only found this out by finally spraying them as described. When I started doing this I stooped losing trees.
 

tanlu

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Thank you for the replies!

I don't water the foliage intentionally, the trees infected aren't very large so I can't really help it. What's weird is that the black fungus was found only on my Ishizuchi five needle pine seedlings, nothing was found on my Zuisho, or my other larger, more vigorous JWP, which has longer, greener needles and slightly different bark. One thing I love about JWP is their drastic genetic variation amongst seedlings.

Vance, I wanted to tell you that your articles on Mugo pines (e.g. Bonsai on the Cheap) were some of the first literature I've ever read on bonsai and it's helped me tremendously! So I definitely respect your experiential knowledge. I'm still looking for suitable Mugo pines in nurseries for pre-bonsai, but it's not easy! I actually got my info from Julian Adams, a legitimate authority on growing of JWP from seed, Zuisho air layer, and cuttings. At the same time, I don't underestimate the importance of understanding each local climate, and he's way down in southwestern Virginia. One thing I do know, from literature and experience, is that JWP seedlings have very sensitive root systems and need to be on the drier side than say Mugo or JBP. We've had an unusually cool wet spring here in New York, which may be the main contributor.

I plucked all the infected needles, mostly all last year's and older. The sheaths of some bunches of new needles had the black fungus too, but after I sprayed it with a fungicide (looks like milk) yesterday and this morning it's pretty much gone. So if I were to show photos, you wouldn't see any signs of infection. I plan to spray it every 10 days until I know it's completely gone.
 
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