Brown Needle tips on Austrian Pine Seedlings

[tranip]

Hello all!
I've been growing a few Austrian pines from seed inspired by the JBP contest.

I've noticed a few of these seedlings have browning tips, some with resin on the browning tips. Any idea what this could be? From what I've seen online it seems like needle blight, but a second opinion would be helpful.

Generally I have them getting 6 hours of direct morning light outdoors (indoors right now for this picture), and they're shaded by a building for the rest of the day. Substrate wise it's a mix of perlite, a clay block and some pumice stone. Watering happens every few days, when I can feel they're fairly dry.
I've also had a JBP seedling with this same expression, however after a few months of doing nothing to it, the new needles look unaffected.

 

[Wires_Guy_wires]

There can be multiple reasons, the most likely is salt stress related: the tips burn due to too many salts in the soil or water.
These can be nutrient salts, or things like sodium (potentially originating from the clay? Can't say for sure).
Other reasons can be high heat exposure, drought, or disease.
Blights are hard to combat and can be lethal for pines, but they tend to attack the whole tree at once, including the new needles. Things like needle cast usually are not lethal, but needlecast should produce horizontal bands on the needles.

To zone in on the cause, can you tell us a bit more about how you treat them? Any nutrients?
Do you see any bands on the needles that we can't see in the pictures?
Are all your seedlings affected, or do some have it less and others more?
Do you have more of that clay block and have you tasted it - please also spit it out - to see if it's salty?

 

[Shibui]

For a start can we please know where in the world so we know if it is spring or autumn where these seedlings live.
Second, as already pointed out, needle cast generally shows up as rings around the needles, not usually the ends of needles.
Brown tips are usually dehydration but that can come form several causes: lack of water; too much water (kills roots), salts (stops roots absorbing water)
Does not look like nutrient deficiency but may be excess nutrient (salts)
Need to know a lot more about how you care for them to give more accurate diagnosis.

 

[tranip]

There can be multiple reasons, the most likely is salt stress related: the tips burn due to too many salts in the soil or water.
These can be nutrient salts, or things like sodium (potentially originating from the clay? Can't say for sure).
Other reasons can be high heat exposure, drought, or disease.
Blights are hard to combat and can be lethal for pines, but they tend to attack the whole tree at once, including the new needles. Things like needle cast usually are not lethal, but needlecast should produce horizontal bands on the needles.

To zone in on the cause, can you tell us a bit more about how you treat them? Any nutrients?
Do you see any bands on the needles that we can't see in the pictures?
Are all your seedlings affected, or do some have it less and others more?
Do you have more of that clay block and have you tasted it - please also spit it out - to see if it's salty?

For nutrients, I use a slow dissolving bonsai pellet. I have a feeling I overloaded the amount of pellets in each pot so salts could be probable cause.
I have seen the bands on other seedlings before but no none on this tree.
Actually almost all my seedlings had this on their first few needles from seed, but the new growth is nice and green.
Haha I'm a little bit of a germaphobe so I won't be tasting the clay block 8)

Thanks for the reply!

 

[tranip]

For a start can we please know where in the world so we know if it is spring or autumn where these seedlings live.
Second, as already pointed out, needle cast generally shows up as rings around the needles, not usually the ends of needles.
Brown tips are usually dehydration but that can come form several causes: lack of water; too much water (kills roots), salts (stops roots absorbing water)
Does not look like nutrient deficiency but may be excess nutrient (salts)
Need to know a lot more about how you care for them to give more accurate diagnosis.

I'm in Toronto, Canada zone 6b and it's fall time about now. Excess salts does seem possible as I'm using a slow release fertilizer and may have put too much of it.

Thanks for the reply!

 

[doipac]

Hi. This is definitely an infection with needle blight (dothistroma). You can see it by the black/brown strips, from where the needle start dying. I can say it fore sure, because I'm flighting to stop a large infection on my pines for more than 2 years now. When it comes to large scale, it's a nightmare believe me, and there is little you can do.

I suspect you have some infected pines outside nearby, that's how those got infected. New needles seem ok, but for a couple of months until the infection gets mature.

 

[Shibui]

This is definitely an infection with needle blight (dothistroma). You can see it by the black/brown strips, from where the needle start dying.

I have also had dothistroma in the pines here but there's always rings around the needles and they do not seem to die as quick as these have died. I cannot see any rings around these needles here, just brown from the tips back along the needles.

Excess salts does seem possible as I'm using a slow release fertilizer and may have put too much of it.

If you suspect this as the cause I would flush with plenty of water to remove what is still mobile then repot in fresh soil in spring. They look healthy enough to hold on till spring.