Garden Talk

with Rebecca Jordi

Q: My citrus tree is dying and I think I have citrus greening.

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Citrus Greening

Citrus Greening

A:  I have had this question 4-5 times within the last few weeks.  First, we do several confirmed cases of Huanglongbing (HLB) here in Nassau County Florida.  The correct name for “citrus greening” is Huanglongbing (HLB).  Secondly, there is no cure or chemical spray to prevent the disease at this point.  In addition, some of the nutrient deficiencies and root decays can mimic several of the symptoms of the disease. Just because your fruit is not totally orange or yellow, does not necessarily mean you have HLB.  We should be diligent about controlling the insect which we believe transmits the bacterium.  I have found it on the citrus at my Yulee office even in January although it is most active in the spring and summer. I would suggest using insecticidal soap or horticulture oil for controlling the insect and the chemical must come in direct contact with the insect to kill it. Neither one of the chemicals listed above have any real residual effect so it is a waste of time, money and chemical to spray the tree if the insect is not present. This means you must see the insect and use the chemical directly on the insect for it to work properly.  Do not use heavy broad spectrum insecticides when the other two work beautifully. Severe cold temperatures in the winter and harsh, hot temperatures in the summer can weaken the bacterium internally once it is inside the tree.  We are hoping this may slow the spread of the disease and provide a few more years of productivity but there are no guarantees. More importantly, how can we predict or be sure either of these environmental conditions will occur? The best diagnosis for HLB is the asymmetrical, blotchy yellowing of leaves.  Think about folding the leaf in half, right down the middle (lengthwise).  If both sides of the leave look somewhat the same, then your tree does not have HLB.  Look over the University of Florida document which will provide the best and most accurate information on identification.  This disease has devastated most of the citrus industry throughout the world.  We will just have to ride this out and hope for the best as backyard growers – it is definitely a deadly disease on citrus.  The fruit will also be medicinal tasting or taste gasoline-like.  This will not improve over time and therefore you should consider cutting the tree down.  Of course, the decision is totally up to you.  http://www.crec.ifas.ufl.edu/extension/greening/index.shtml

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