Keep in mind these courses from Bob are not just "on-line courses" but from an accredited college with those associated credits. You may take a single course or pursue a diploma or a degree as you wish.
There has been criticism on the quality of on going education available from our national and international organizations. I am surprised that more accredited institutes do not offer more in the way of specific arborictultural education. They are mighty quick on the ag and forestry industries which still leaves the residential arborist to scratch and dig for information and recognition.
When my wife decided to more seriously pursue further education in the arboricultural field, she searched high and low looking for legitimate and quality courses and information. The price is a bit of a gulp. However, that price tag also ensures a commitment to the course. When something is free, it is easy to breeze over and not truly assimilate. When you spend some money, you want to be sure you get your money's worth.
My wife found the hands-on labs valuable. Requiring extensive field work, involving interviewing homeowners/grounds managers, sample taking and interrupting, copious picture taking, developing power point programs, journals and reports to submit for grading. Not everyone's cup of tea but produces a well rounded understanding of the subjects discussed.
The amount of knowledge she has learned has been significant and these classes so worthwhile that she is continuing with the end of achieving the Urban Forestry Management diploma together with a Landscape Design Technology diploma.
Financially we have to spread it out. But the time committment for each class is substantial. This requires that she do that anyway as we are still working.
Dave