First you are trying to fertilize a container tree with an organic fertilizer (Citrus Tone). What makes organic fertilizers, such as Citrus Tone, available to the tree are microorganisms. Soil microorganisms react with an organic fertilizers to break them down into a form available to the tree. However, container culture does not contain enough microorganisms to achieve the nutritional availability of your fertilizer. Organically derived ferts are extremely inefficient when applied in a container setting. And they also tend to lack many of the required micronutrients. Your tree would be better served with a liquid synthetic with a full range of required plant nutrients and in the correct proportions - something like Foliage Pro 9-3-6. To another point: the period of greatest leaf fall in citrus is during the bloom. The highest stress period for the tree is during the bloom and fruit development phase, therefore during this time nutrition is extremely important.. Your tree is showing various nutrient deficiencies. I would strongly recommend that you switch to a conventional fertilizer with a higher formulation ratio of nitrogen and potassium, and less phosphorous, plus the micronutrients. The medium that your tree is growing in looks to be pretty tight/compact. How rapidly does the water drain out the bottom of the container after you apply water?