Subalpine Fir Trees and Lawns

Factual Questions
1

I have mainly Subalpine Fir trees (Abies bifola) on my property in Western Montana. I have noticed this year that there has been some kind of resin being secreted by the trees either onto their needles (making them shiny) or onto the ground below the tree.

It’s been a particularly hot summer here with little relief or rain. This resin tends to be more noticeable on the western side of the tree which makes sense since the hottest part of the day is in the later afternoon when the sun is in the western sky so the western side of the tree gets hotter than the eastern side.

I also have a large lawn in my backyard I water frequently and that is doing well in the hot weather accept for two large (3 foot by 6 foot) patches of dead grass. Both patches are directly under fir trees and both are on the western sides of the trees. I am assuming that whatever these trees are secreting is killing the lawn in these two areas.

Is it likely that the trees are to blame for these two dead patches and is there anything I can do to combat the problem? The lawn has been getting plenty of water in these two areas and it doesn’t seem to be making any difference.

2

Really? Nobody has Fir trees on their lawns?

3

Grass doesn’t usually grow well under pine trees because it doesn’t get enough sun. If your trees are tall, you can remove the lower branches to let more light in and rake up the needles so the grass isn’t smothered.

I don’t want to say the resin is having no effect at all, but I suspect lack of light is a bigger problem.

P.S. It’s not great for the tree to have grass growing directly under it, since it competes for moisture and nutrients. You could let fallen needles form a natural mulch and think of it as a feature.

4

You could ask these folks: http://nhguide.dbs.umt.edu/index.php?c=plants&m=desc&id=100

5

The trees are making the soil acidic and stripping it of nutrients, you could try spreading lime and fertilizer to make the area more grass-friendly.