My grapefruit tree has not been producing the last two years. I got my Ruby Red grapefruit tree in March 5 years ago when it was about 2 1/2 feet tall. That summer I had many blossoms which ended up yielding 3 golf ball sized grapefruit. The next year I had about 8 tennis ball sized fruit. The 3rd year I had 14 grapefruit sized fruit which were really good. Last year (the 4th year) the plant did not produce any blossoms. This year it is looking about the same as last year with no blossoms in evidence. The plant is now about 5 feet in height. What do I need to do?