Key Lime Plant Zinc Deficiency Causes, Symptoms and Treatment
If your key lime tree (or other citrus plant) seems to be dying, figuring out what’s wrong can be a nightmare. Overwatering, underwatering, too much sunlight, too little sunlight, pests, root rot, soil acidity, all of these things can affect a plant. One possible problem, though less discussed, is a zinc deficiency.
If your plant’s leaves are not smooth and an even dark green, there is something wrong with your plant and you should address the problem before it becomes severe. Plants can re-grow even after they appear to be dead, but addressing problems earlier is better. I had a plant so severely zinc deficient that it lost all its leaves and the branches had died back by half an inch per day until, by the time I found out the problem was a zinc deficiency, the plant appeared to be dead with no chance of recovery. Six months later it was healthier than it had ever been with little trace of its former trauma.
Causes and Symptoms
Zinc deficiency in citrus trees is caused by inadequate or improper fertilization, and can also be caused by excessive watering. If you use a fertilizer specifically formulated for citrus plants, if you fertilize regularly (once every month or two), and if you water once a week, you shouldn’t run into a zinc deficiency. If you see any of the following symptoms, though, your plant could be lacking in the mineral.
Early indicators of zinc deficiency include stunted plant growth and leaves with yellow blotches. The leaves will likely not be smooth; they can appear wrinkled or bumpy, or could be curled. Your plant will not produce much fruit, if any.
As the deficiency progresses, the leaves will drop, and the plant could even lose all its leaves. New leaves may appear pale and highly pointed, often pointing directly upward. As it grows even more severe, the branches will die back, with the green branches turning black and the branches with bark showing no green underneath. New growth at this point will likely die quickly.
If you catch symptoms of zinc deficiency, the first thing to do is stop fertilizing if your fertilizer is not specifically formulated for citrus plants. If you are using an improper fertilizer, chances are that you will exacerbate the symptoms of the deficiency. Water the plant with lots of water in one sitting to wash away excess fertilizer. You may use many gallons of water, but your goal is to clear the soil of some of these chemicals, so you want lots of water to drain out, taking the fertilizer with it.
Your next step is to apply two substances (both of them stain clothes, so be careful). The first, and most important, is a chelated mineral mixture containing iron, copper, manganese and zinc. The mixture and balance of minerals will enhance absorption. This will be a liquid, and you can apply it both topically and mixed in the plant’s water. You can only water once every 5-7 days, so applying it topically is also extremely beneficial. Put some of the liquid diluted with water in a spray bottle and mist the remaining leaves and branches daily (or multiple times daily, depending on the severity).
The bottle with the chelated minerals will give directions and guidelines for how concentrated to make your solution, but if you’re dealing with a severe deficiency, don’t worry about putting more than recommended. When my plant was at its worst, I was likely putting three times the recommended concentration on both the branches and the roots, but this also runs the risk of damaging the plant’s tissue. Use your judgment.
Your plant may also be suffering from other nutrient deficiencies, so the second substance to start giving your plant is citrus fertilizer. Again, you can put the fertilizer on in a higher concentration. Your goal is to restock the soil with the missing nutrients.
In the early days of recovery, new growth will likely die quickly as the plant is still lacking the nutrients required to create sustained growth. Just keep doing what you’re doing, and after a few weeks, the growth will be stronger and stronger. In fact, once you’ve fully replenished the plant’s nutrient base, you will likely be amazed by how fast and strong new growth is.
If you detect an abnormality in your citrus plant, address the problem as soon as possible. If you see yellow blotches on wrinkled leaves, your plant is probably suffering from a zinc deficiency, the severe stages of which can include total leaf drop, branch dieback. Clear the soil of inappropriate fertilizers and apply chelated minerals both topically and in the water. Fertilize with citrus fertilizer. Even seemingly hopeless cases can be treated in this way, though the results will not be immediately apparent.