During the first few years, apply fertilizer to young trees to stimulate vigorous growth of leaves and branches that will become the framework of the mature tree. Beginning about 2 weeks after planting, frequent light applications of fertilizer should be made approximately every 6 weeks. Fertilizer should not be applied between October 1 and February 1 for the first year or two, most especially in colder regions. The goal of the fertilizer program for young fruit bearing trees is to continue to stimulate vigorous growth of leaves and branches that may compete with early fruit production. After the tree has become established, the goal will be to replace nutrients removed by the fruit and to provide enough nutrients to sustain continued tree growth. Many different fertilizers formulations are available for use on dooryard citrus trees. In general, the numbers on a fertilizer bag refer to the percent of nitrogen, phosphorus and potassium plus other secondary and micronutrients. For example if the numbers 8-8-8 were listed on a fertilizer bag it would contain 8% nitrogen, 8% phosphorus and 8% potassium. Other nutrients like magnesium, copper, and boron may also be listed. This type of fertilizer would be ideal for a nonbearing young citrus tree. Higher analysis, mixed formulations such as 10-10-10, 12-12-12, or 15-0-14 are used on mature trees. A 1 year old tree should be fertilized 6 times a growing season. A 2 year old tree should be fertilized 5 times per season. Three year old trees 4 times per season. Four year old trees and older fertilize three times a year. For young trees, apply fertilizer uniformly in a 3-ft. diameter circle around the tree. As the tree becomes older, the area fertilized should be enlarge as the root system expands. As a rule of thumb, fertilize an area twice the diameter of the tree canopy. Care should be taken to avoid root or trunk damage by uneven placement or mounding the fertilizer against the trunk. Purchase real fertilizer for your tree. Personally I would not use fertilizers such as Dr. Earth and Alaska Fish fertilizer, your tree needs a real fertilizer. Just looking at the tree it is quite easy to see that the poor thing is struggling to find some food to live on. The best to you and your tree.