AusBonsai

Hi all, I was hoping those more knowledgeable than me might be able to offer some clues about what I'd been seeing on a couple of landscaping pines in my garden.

I've been developing the japanese black pine as a niwaki style tree for a few years and it has always been pretty healthy and vigorous but I've only had the Bosnian pine a few months and haven't really done anything to it beyond planting it and giving it some seasol and powerfeed.

The Bosnian pine in particular has dropped a large number of what I had initially thought were just old needles but when I was looking at it today I noticed it had a lot of little lighter coloured spots on many of its newer/mid aged 1/2 year old ones.

I likewise noticed the same thing on my Japanese black pine and am a little curious/alarmed as to what it might be?

The first two pics are of the bosnian pine and the second two are the needles on the japanese black pine

Not much to worry about. Possibly some hail damage in there. Otherwise healthy

Mike could be that but there is a disease that usually shows in the form of a band on the needles. Proberly ask Joe he is pretty clued up on this.

Matthew wrote: ↑January 11th, 2020, 1:39 pm Mike could be that but there is a disease that usually shows in the form of a band on the needles. Proberly ask Joe he is pretty clued up on this.

yes the yellow bands could be some fungal issue but nothing very serious.

Dothostroma is the fungal disease that affect spines and shows up as bands of yellow. I have not had to deal with it here yet but have seen reference to other growers where it occurs.
Dothostroma is rarely fatal so trees live but all infections that affect foliage do set the trees back by a certain amount depending on the severity of the problem.
Copper sprays are said to be effective treatment and there are probably other newer fungicides that treat leaf problems. I don't know of any fungicides that are detrimental to the tree if the diagnosis is wrong so it would probably be worth investing the small amount of time and money on a treatment program. Preventative spray for any pines in the immediate area would also be worthwhile.
The damaged needles are permanently damaged. Treatment will jut stop the problem from spreading and getting worse.

As always, just my Take it or leave it.

Hi mate,

I experienced a very similar issue that affected just about all of the pines I have. I noticed yellow spots developing on needles in late winter with some being worse than others. From my research it is a fungal infection that is contracted prior to the yellow spotting occurring, meaning that the pines could have been infected months before signs being present.

I sprayed mine a couple of times in early spring when candles began to extend with a copper based fungicide hoping to get rid of the infection ahead of it getting to the fresh needles. I didn't see yellow dots on any of the spring growth. I've just sprayed all pines again, specifically the ones I cut candles on with new buds to prevent the fresh flush being infected.

I should mention that it hasn't seemed to slow them down at all, everything pushed strong Spring growth and have back budded after cutting candles as expected. Ill report back in Winter to see if I've managed to get rid of it.

Definitely dothistroma (needle cast, needle blight).
My pines used to suffer this fungal attack quite badly due to the high humidity where I live.
Spores set in on new needles from when candles start opening up until the needles harden off. However, symptoms (banding of needles and die-off above the banding) don't show until summer or autumn. By then it is too late to treat. So, best preventative treatment is to take care of any potential spores while new needles are soft.

Best treatment is chlorothalonil. I spray chlorothalonil on all new growth every fortnight until needles harden off, and haven't seen any symptoms since I started doing this.
While Daconyl is banned for retail sale here in OZ, chlorothalonil is not impossible to obtain under alternate names here in Australia.

wrcmad wrote: ↑January 12th, 2020, 6:30 pm Best treatment is chlorothalonil. I spray chlorothalonil on all new growth every fortnight until needles harden off, and haven't seen any symptoms since I started doing this.
While Daconyl is banned for retail sale here in OZ, chlorothalonil is not impossible to obtain under alternate names here in Australia.

For the most part i've not really had a problem with blights up until now really, but last years constant drizzle might have made conditions more favorable for a little outbreak

Can you recommend any particular chlorothalonil fungicides that you've found work well (and are likely to be available)?

Dothistroma is a serious issue and if left untreated can kill your tree, I wouldn't ignore it.
It is important to treat it before your new buds appear after your summer candle removal, otherwise it will transfer to your new needles. I always spray with Kocide Blue (available from the big warehouse with the big red hammer on the logo). Kocide blue is a soluble powder that you mix with water.

+1 for Kocide, we use it at work and it’s highly effective.

damienw133 wrote: ↑January 16th, 2020, 7:37 am Can you recommend any particular chlorothalonil fungicides that you've found work well (and are likely to be available)?

This one is readily available: