correlation of stem canker disease, caused by botryodiplodia theobromae pat., and die back symptoms on guava trees and practical solutions for disease control
Abstract: Abstract:
During July – august 2009, a severe stem canker and die back symptoms were observed on guava trees (Psidium guajava) in different locations in Kaliobya governorate, Egypt. Isolation, pathogenicity tests and identification of the causal agents proved that the causal organism is Botryodiplodia theobromae Pat. The behavior and effects of B. theobromae on various plant tissues were histologically studied on artificially infected one year old guava plants after 7, 14 and 35 days from inoculation. The fungal hyphae completely colonized the cortical cells surrounding the wound site after 7 days of inoculation. After 14 days, the epidermal and cells showed plasmolysis and disorganization with a dark brown discoloration in addition to the destruction of the most of phloem and cambial cells. The xylem rays seemed to be a suitable pass ways for rapid and easy extension of the hyphae and the intercellular spacer filled with fungal hayphae. Section of 35 days old samples showed that, the disease had rapidly and intensively progressed through the tissues and showed necrotic area in both xylem parenchyma and xylem vessel, colonized by hyphae, and dark inclusions inside the xylem and vessels particularly metaxylem were plugged with gum and pith tissue colonized the fungal hyphae. The present study suggested that the appearance of die back symptoms with stem canker symptoms might be due to the presence of necrotic vessels and plugging with gum and/or tylosis which cause a dysfunction of xylem with destruction in water flow. Among the tested fungicides carbendazim and Thiophanate –metrhyl proved to be the highly effective fungicide against stem canker of guava after the 3ed spray.

Keywords: Botryodiplodia theobromae, Psidium guajava, Guava trees, Stem canker, Die back, Histopathology, Chemical control.
Publication year 2011
Pages 183-198
Availability location http://www.acepsag.org/journal/vol6/issue4/12.htm
Availability number
Organization Name
serial title .J. Biol. Chem. Environ. Sci
Author(s) from ARC
Publication Type Journal
↑