Epiphytic hosts identity of citrus blast causal agent and their impact on disease management

Iran is an important country exporter of citrus fruits and ranks seventh in the world in terms of production. Citrus blast disease is prevalent in most parts of the world's citrus crop. Blast symptoms often occur as water-soaked lesions or black areas on the blade and petiole that gradually expand and eventually cause drying twigs. It seems the citrus disease agent is transmitted in the warm months on the herbaceous plants and epiphytically survives on them. Due to the high intensity of blast disease and its considerable damage in the Caspian region (northern Iran), identifying epiphytic hosts and their control may have a significant role in the management of citrus blast. Accordingly, in the present study the weeds Cynodon dactylon, Convolvulus arvensis, Lolium temulentum, Cyperus sp., Amaranthus retoflexus, Romex acetusella, Senecio vulgaris, Agropyron repens and Eleusine indica that grows abundantly in citrus orchards were identified as owners of the potential of epiphytic maintenance of disease agent. In next step, the host weeds are controlled chemically or mechanically (in a randomized complete block design) in two large orchards, and their effect were studied on disease occurrence. The best result (minimum disease symptoms outbreak) was achieved by chemical treatment of weeds using Roundup, indicating its significant difference than mechanical treatment. Also, mechanical treatment of weeds significantly reduced the appearance of the disease compared to the control. Hence, current study proved that the removing inoculum sources significantly reduces disease incidence.

کلیدواژه ها:

Citrus ، blast ، survival ، weed ، chemical control ، mechanical control