Sally Scalera
Brevard County Horticulture Extension Agent
3695 Lake Drive -- Cocoa FL 32926 -- 321-633-1702
Citrus tree problems
June 12, 2010
This spring I have received more questions concerning citrus tree problems than all other gardening topics. It turned out that all of the problems stemmed from insufficient fertilizing and watering of the citrus trees. In addition to the cultural requirements, citrus also has three diseases (canker, greening and the newest arrival – citrus black spot) that we need to protect the trees from. Check out the list below to see if you are doing all of the things listed to grow healthy citrus trees.
The general recommendation for fertilizing mature (over five years old) citrus trees is to fertilize them three times a year using 6-8 pounds of 6-6-6, 4 ˝ -6 pounds of 8-8-8 or 3 ˝ -4 ˝ pounds of 10-10-10. Younger trees can be fertilized with fewer pounds per application but they can be fertilized more times each year. To get a copy of our bulletin “Citrus Culture in the Home Landscape”, which has a table showing the fertilizer recommendations, go to http://edis.ifas.ufl.edu/pdffiles/HS/HS13200.pdf or call us at 633-1702 and give us your address.
If you have never ever had a soil test done then do so before fertilizing next. After the test results are in you will know what nutrients you will need to add. You don’t have to have a soil test done each year but it is good to have one done about every three years. For $7 the U of F Soils Lab will test for pH, phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca). It is important to find out if you need to apply more of a nutrient or compensate for too much of a nutrient. Obviously, if you already have high or very high levels of a nutrient(s) there is no reason to spend more money when you don’t need to and secondly, if you have very high levels of these nutrients they will interfere with the absorption of other nutrients which can cause deficiencies in the plant. Too much phosphorus will interfere with the take-up of zinc (Zn), iron (Fe) and copper (Cu); excess potassium will affect nitrogen, calcium and magnesium absorption; high levels of magnesium will affect calcium and potassium and too much calcium will affect phosphorus, magnesium and boron up-take. So, for example, if you have over applied potassium you can induce an iron deficiency in your plant.
Right behind fertilizing in importance is giving citrus trees supplemental water every 7-10 days if they haven’t received at least one inch of rain. A rain gauge in your yard is really helpful in determining how much rain your yard receives each time it rains. For those times when you need to water, make sure that you wet the entire area underneath the branches with one inch of water. Rotary irrigation heads will need a longer run time per zone to apply one inch of water compared to stationary, pop-up heads.
Remove all grass and weeds underneath the branches of the tree and mulch the area with 2-4 inches of pine bark nuggets or wood chips. Be sure to keep the mulch at least six inches away from the trunk.
Supplement your granular fertilizations with foliar applications of liquid seaweed. Liquid seaweed contains more than 60 trace elements and growth hormones and has been shown to help plants through stresses like flood, drought, cold temperatures and even the good stress of producing fruit. Foliar applications of liquid seaweed can also help to correct a minor element deficiency caused by a lack of the nutrient in the soil, pH problems that tie up nutrients making them unavailable for the plant to absorb or high levels of nutrients that affect the absorption of other nutrients. For more information on using liquid seaweed (which is also a must if you vegetable garden or grow any plant for the food it produces) call us with your address at 633-1702 or email me at sasc@ufl.edu.
Though there are a few things that we need to do to help our citrus trees stay healthy and produce fruit, it seems worth the effort when you get to enjoy a juicy naval orange, handpicked from you own tree!
|
