Over the years, I’ve received thousands of leaf, stem, and soil samples from gardeners who need help figuring out why their plants aren’t growing the way they should, and how to get them back on track.
Often, the diagnostics are pretty straight-forward and simple. If the problem is a large insect - like a cabbageworm - identification is pretty easy and there are a number of good products available for control.
But many plant problems are more complex than voracious cabbageworms, and a lot of background information is critical when performing the "Plant Forensics”. Good samples of plant parts, lots of good photographs, soil samples, and historical data are really valuable tools for solving the really difficult plant problems.
Since trees are some of most high-priced and expensive garden plants, they comprise the majority of the plant samples that I receive and they are often the toughest problems to solve.
The one tip that I will offer those who have tree problems is to spend as much time looking "down" as you do looking "up". Trees are analogous to icebergs in a way. Just as about 90% of an iceberg’s mass is below the sea surface, 90% of the serious problems that I see with trees originate below the soil surface.
And neither ships nor trees fare well when due consideration is not given to what lies below.