root rot in pine seedlings !

by umar khan
(islamabad, pakistan , south asia)

So I planted these seeds of pine trees (Pinus roxburghii) around 100 plants. 75 of them grew out okay its been almost a month ..now.. but they have started to rot now.. the small plants feels really really soft .

The plants are being grown in south asia.. where temperature is 97F.. HUMIDITY IS 25 percent .. I've used sand soil and animal waste as fertilizer. I water plants 2 times a day when the soil dries up .. the roots are turning from white to light yellow !

1. what am I doing wrong?
2. what should I do to keep my plants in good health ?..

ps one more thing some of the pants , their soil has a green layer of fungus over them too! .. I mean I've created really good drainage for them too! please help me out in this
and please also tell me for how much time should I keep them in the sun. noting that the sun is really intense !

Comments for root rot in pine seedlings !

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Jun 17, 2020
 You did one thing right
by: Jacki Cammidge, Certified Horticulturist

The good drainage part of your regimen is right, but everything else is not.

First, these trees live in dry areas, very sandy and acidic. No manure, or compost, other than pine needles.

They also do not like too much moisture, even as tiny seedlings. Reduce the watering to one or two times a week - make it a good one, not just a tease, then let them dry out.

There's not much you can do about the humidity, but you can provide more ventilation, like a fan for most of the day. Professional tree nurseries always have air exchange going on, night and day, and here in British Columbia, even if it doesn't get that hot, it can still be over 90% humidity.

And, get them out of the sun! Where they prefer to be as seedlings, in nature, is in the shade of the mother tree. The seeds fall from the tree in a downwards direction, or are ejected from the fallen pine cone, right under the mother.

So, the seedlings need shade, when young. Filtered sunlight, as in shade from branches or 50% shade cloth will be enough.

There will be changes in the color of the roots. As they mature, the tips will stay white, but the rest of them turns darker, yellow or tan colored.

I'm not sure how you would be seeing the roots, when the seedlings are in those bags. They're impossible to turn upside down to dump the plant out without disturbing the seedling, which could definitely kill them.

And, you do know that 75% germination is about what you can expect from some species? You may have losses yet, but that is a good germination percentage. A lot of pine species need heat to germinate, as in a forest fire.

Keep me posted, and let me know if you have any other questions.
Jun 17, 2020
 Also
by: Jacki Cammidge, Certified Horticulturist

Sorry, forgot to answer your question about the green on the soil. This is most likely either moss or algae, which doesn't harm the plant, except that it smothers the roots a bit and tends to make them dry out as water doesn't get below it.

Easy fix; sprinkle a layer of turkey grit/small gravel on the surface so it will kill off the algae by cutting off the light. This won't harm the pine trees at all. Mostly it's unsightly.

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