Sick Giant Sequoias
I'm Christos from Greece and I've got two 15 inches tall Giant Sequoias planted in 5 liter pots,I bought them last December and they were about 5 inches tall. So far they were doing great, but one month ago they don't look very healthy. I discovered a few weak and brown colored branches and needles. Note that i allow the soil to barely dry between waterings, temperatures in my area this time of the year reach around 30 - 35 degrees celcius during the day. Is there any fertilizer of specific content you could recommend and when is the best time to transplant them to the ground or a larger pot? I asked for advice from a U.S nursery specializing in Sequoia trees and they said it might be just a blemish, they also suggested using a fungicide effective against botrytis fungus. I thought i ask for a second opinion. I've already sprayed the one sequoia with a fungicide against botrytis cinerea and applied a small dose of iron (Fe) on both of them and removed the affected branches. I also bought a conifer fertilizer 9+6+11 with Magnesium, would that do or should i go for the 20+20+20 i read somewhere? What should i do?
This photo was taken a month ago, now it looks worst.