Someone help! I'm a renter in zone 7 and my landlord cut down a pine tree for me that was threatening to topple. Problem is, it was "sheltering" one side of a large holly. That side is pretty much dead, and it appears to have a mildew (or some white coating) problem. My mom suggested cutting out all the bottom branches so that the tree could get more air - is this a good idea? And how do I get rid of the nasty mildew?

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Snapdragon

So I just checked a bit more and what was white earlier in the season is black now, maybe as the organism dies off it darkens? Also on the backs of some of the leaves a very short very straight little white lines. Like an egg deposit or something.
Any advice?

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Snapdragon