Hi everyone,

I have a question regarding my nagami kumquat. This is my first and only kumquat tree. I bought it about 7 weeks ago and planted it in my front yard. I have been watering it once a week since then (well I believe I watered it twice a week occasionally). I also used some 10-15-10 fertilizer on it (once).

What's happening is some leaves gradually turned yellow. Some leaves fell as well. I did some research and convinced myself that my kumquat needed iron. So I bought some liquid iron and spayed the leaves with it. Actually I'm not sure if this is the right thing to do. So I would like to get some advise/comments from you experts before I further mess around with it. I have attached a picture in this post.

I live in northern California. My front yard is facing south so the kumquat gets full sun. The temperature in the night is in the 40s.

Thanks in advance for any comments.

I'm not an expert but it does look like iron deficiency to me or possibly zinc or manganese deficiency. However, foliar application of iron is not recommended for citrus. High pH, excessive watering, water logged soil, and cold weather are often causes of iron deficiency so rushing to apply iron is not necessarily the right solution. I vaguely remember someone saying that kumquats do this when it's cold.

Here are some links to publications that may help you.

identification of deficiencies

http://edis.ifas.ufl.edu/ch142

iron, zinc, and manganese deficiency

http://edis.ifas.ufl.edu/ss423

and the index

http://edis.ifas.ufl.edu/topic_citrus_nutrition_and_fertilization

nvm all wrong on my end

First, Welcome to The Citrus Growers Forum. Thank your for becoming a member. 10-15-10 is not a very good formulation for citrus. As you have not listed your location, it is difficult to be sure that a totally correct advice can be given. For in ground citrus trees less than 3 year old, you should NOT apply a fertilizer having a nitrogen content greater than 8 percent. . Young 1 or 2 year old citrus trees planted in the ground, such as your kumquat, should be fertilized 5 times a year equally spaced out between February and September. Recommend fertilizer formulations for a tree of the age of your tree, is either a 6-6-6 or a 8-8-8. Your tree looks to be a 2 year old tree, so it should receive 0.6-lbs. of actual element nitrogen (NOTE: not 0.6 pounds of fertilizer granules) per year. So if you use a 6-6-6 apply 1-lb. of fertilizer with each of the applications. For a 8-8-8 formula fertilizer apply 3/4-lb. (.75-lb) with each of the 5 applications. 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 enlarges as the root system expands. Care should be taken to avoid root or trunk damage by uneven placement, or mounding the fertilizer against the trunk. The deficiency that your tree is currently showing looks to be an iron deficiency, which always shows up on the new leaves. It is not recommended to apply iron as a foliar spray. Apply iron either as iron sulfate, or chelated iron, through the roots - Millet (1,023-)

Hello,

Your fertilizer formulation presents too much phosphorus.

Phosphorus in excess stops your kumquat from assimilating iron. Actually, it creates an iron deficiency.

Franck

First of all, thank jrb, Millet, Franck for your advises. It seems I have made a few mistakes here. I'm a newbie gardener. I'm glad I asked questions before I make more mistakes.

Now back to my kumquat tree. I said I used 10-15-10 fertilizer on it once. I want to mention it is a liquid fertilizer and I used only small amount of diluted fertilizer. I hope that hasn't hurt the kumquat too much. Millet, since I just planted the tree in the ground about 7 weeks ago, I don't have to apply any fertilizer, right?

As to the iron deficiency, jrb mentioned a few possible causes. After some thinking, I start to believe I might have watered it too frequently. I'll decrease my watering frequency to see if it helps. Another thing that bothers me a little is that I don't recall seeing new leaves coming out on my kumquat tree (I'm not 100% sure though). What could be the cause of that?

Thanks again. You guys are very nice.

Citrus grow in flushes or spurts--then rest a while as the roots grow. Kumquats will be one of the last citrus to start growing in spring--mine have shown no sign of new growth.

If you tree has deficiencies it has more to do with how it was maintained in the container--it has not had time to adjust to your soil. If new growth continues to show signs of deficiencies, I would suggest checking pH first--it is a controling factor in mineral uptake.

Yellowtiger, during the first few years, applying fertilizer to young trees is to stimulate vigorous growth of leaves and branches that will become the framework of the mature tree. Beginning about two (2) weeks after planting, frequent, light applications of fertilizer should be made approximately every 6 weeks. Avoid burning roots with high levels of soluble fertilizer applied all at once. Fertilizer should not be applied between October 1 and February 1 for the first couple years. This will reduce the possibility of untimely growth flushes in the winter. Once your tree begins to bear fruit, the goal of the fertilizer program for young 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 with the fruit and to provide enough nutrients to sustain continued tree growth. - Good luck with your tree. - Millet (1,023-)