Beginner Gardening: Question about thuja diseases, 0 by Ocean66

Ocean66 wrote:
I planted 5 of these thujas in August of this year. Did put some triple mix, followed instructions and few days later 3 of them got this blackish marking mostly on bottom of them.
I took some branches to the various green houses and got various answers...fungus, mildew, stress due planting and heat.
Now first and last one in row are completly dry. They all got same treatment but not sure what might happend.
Also I have one thuja in pot for over 2 years now and this one is doing great.
Thank you for help.