Thank you for waiting. Ponderosa lemons don't normally need much trimming or pruning. You should prune out any dead or damaged branches, and also any that are crossing or rubbing on other branches. The tree should be fertilized during the growing season, but not during the winter. However, since it is budding again, that is an indication that growing season is here. The only other routine care you need to do is check the pH of your soil. Ponderosa lemons do best with a pH between 5.5 and 6.5. If yours is too high, you can get soil amendments to adjust it at a garden center or nursery. Agricultural sulfur is one such product. Provide water during drought, but make sure the soil is well-drained, nothing will kill a lemon tree faster than standing in soggy soil. Once the trees are established (and yours is), they need very little care beyond what I've described. They tend to set no more fruit than what they can grow successfully, so you can leave the buds alone. However, it also won't hurt to thin them out by removing a number of them if you're afraid the tree will be stressed.
You probably don't need a specialist unless the tree is showing signs of disease or pests. If you decide to consult one, just look for a certified arborist. There are a lot of companies billing themselves as 'tree care specialists' and similar titles, but a certified arborist has attended college to become an expert in tree care and has passed a test, as well. This link will take you to a directory of certified arborists so you can find the nearest one:http://www.isa-arbor.com/faca/findArborist.aspx
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