Citrus is one the most commercially grown perennial fruit crops world over under a wide range of soils and climate . There is hardly any citrus belt, free of either greening disease or zinc/iron deficiency. Morphologically , over-lapping symptoms of greening( Huanglongbing) disease and zinc/iron deficiency are produced, and both are erroneously identified using symptomologies as the only basis of diagnosis, with the result, the remediation of either of the two is hardly achieved. Is there any field technique available to precisely identify the greening symptoms to zinc/iron deficiency. Needless to say , it takes years before such distinctive symptoms appear to caution the growers, much damage to both production and quality is already done . And , as of now , these two are very difficult to separate from each other in field.
It is very difficult to differentiate a plant infected with HLB of a plant with plant nutrient deficiencies. However there are some differences that may indicate an infection by HLB. Infected plants show chlorosis only in some random branches, while plants with nutritional deficiency chlorosis shown around the tree.
In leaves, the chlorosis caused by infection is asymmetrical, being observed only in one of the two sides of the leave. Also infected leaves usually displayed thicker and leathery and with corky veins.
Some pictures here:
http://idtools.org/id/citrus/diseases/factsheet.php?name=Huanglongbing+(HLB)
Interesting Eugenio. With regard to first part of your response , in infection with HLB, noly few branches express symptoms of HLB , but in case of nutrient deficiency , it is more uniformly distributed . I agree to some extent , but sectorial deficiency of Zn/Fe (Due to poor vascular connection between root and shoot ) is very common in citrus .Yew , asymmetrical distribution of chlorosis symptoms is more precise to diagnose the HLB from nutrient deficiency.
Is there any rapid field test available anywhere to differentiate HLB from nutrient deficiency.
Let us be candid on this issue which is one of the most practical issues confronting the citrus growers in day-to-day life. I invite the precious views of the researchers worldover to be expressive on the subject .
I don't think there is a rapid field test to differentiate HLB from nutrient deficiency, but I recommend that you take a look on professor Roistacher book, he is simply the most experienced scholar dealing with citrus stubborn disease
I attach the book here for you
Thanks Dr Mannaa. This is a very useful publication . But , you are right, we dont have practical field tests to discern greening from nutrient deficiency . We still rely on the improving the nutritional status of the infected plant , especially the Fe/Zn concentration , as a part of the management strategy of greening .
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