تأثير الإصابة بمرض الإكزوكورتس في نمو و إنتاج أشجار الليمون صنف ماير محسن

الملخص EN

Exocortis is one of the important viroid diseases on citrus, which caused economic losses such as yield reducing, dwarfing and death of some susceptible rootstocks and varieties.

This study was carried out during 2011 to 2013 at a citrus grove near Tartous (Syria) cultivated with 8 years old improved Meyer Lemon trees grafted on Sour Orange.

The disease was detected by indexing on the indicator plant Etrog Citron (Citrus medica L.) grown on rough Lemon (Citrus jambhiri Lush.) rootstock.

External symptoms were elongated bark cracks like goves, stunting of trees, reduced yield, smaller fruits, yellowing and pits on the bark of young branches and chlorotic stem blotching, these symptoms showed that the percentage of infection reached to 15 % in the studied grove, which confirmed by indexing test.

Viroid infection reduced branches annual growth rate, crown diameter and tree height and volume by 53, 20, 22 and 50% respectively as compared with healthy trees.

Annual yield was reduced 87% during 2011.

Furthermore, viroid infection reduced the previous parameters by 28, 21, 25 and 53%, respectively and 90% for yield during 2012.

Similar results were found during 2013.