Fertilizing your bonsai tree is one of the most popular topics in bonsai. The most common issue however is when new enthusiasts fertilize improperly. E.g. when a tree looks sick or weak, fertilizing it too heavy in hopes that the extra food will save it. Most often this causes the complete opposite result. The added nutrients and chemicals will prevent the tree from healing naturally and instead overpower the tree which can in turn kill the tree.
When working with black pine bonsai trees, over-fertilizing has other negative effects. Black pine bonsai trees are best known for short needles and compact growth. This will happen completely perfectly without fertilizing. However if you over-fertilize your tree, the result can be two things. The needles will grow too long or the length between the nodes will be too long.
However, all is not lost if this occurs. You can make changes that can bring your tree back to normal growth. To correct shorter needles, you can just keep up on your regular maintenance and over time the needles will get shorter. Putting your black pine tree in direct sunlight will also help to shorten the needles as well. Longer nodes (developed due to candles that are too strong) are harder to correct as you will have to work with leggier and thicker branches that can sometimes make your branch look too thick for your tree. Most often with this scenario, you will have to use inside buds to develop your branch and eventually sacrifice the leggier branch.
Ultimately the best scenario is to use moderation in your fertilizing. This way your tree will growth healthy and at a normal pace.