I planted six 6ft. Leyland Cypress trees as a screen next to my driveway in...
I planted six 6ft. Leyland Cypress trees as a screen next to my driveway in 2007. Four of them are growing very well and look healthy. They are now about 15 to 18 ft. tall and nice. But two trees are not doing so well. They look stressed, leaf colors are pale and while they have grown some in height their diameter is much smaller and not full like others. I called a tree service company and they recommend scheduled fertilizer injections which is quite costly. But as I do a little web search, I find opinion that injection is no better than broadcast method and recommend doing a soil test first to determine if there is any disease. Can you please advise, how I approach to solving the problem.
The problem is almost certainly a site problem, i.e. those two have poor drainage, or different soil underground, large rocks, or perhaps the area was once part of the driveway and the soil is terribly compact or gravel.
This is no simple solution. You might want to dig down near the tree and see what's under the soil. You can try to improve the nutrients, aeration and drainage of the spot by mulching with organic mulch, or adding organic composted materials to the soil surface. Never let mulch pile on or touch the trunk. It should be no more than 2-3" deep at most. If you do fertilize, use a slow release fertilizer. Keep in mind that most fertilizer are salts, and they can stress an already-stressed tree even more.
Please read our online publication about abiotic causes of plant problems such as girdling roots or planting too deeply: http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG201%20Homeowner%20...
Water during droughts.