تقصي انتشار مرض لفحة فيوزاريوم سنابل القمح و مسبباته، و التباين في قدراتها الإمراضية في سهل الغاب في سورية

Abstract EN

A survey of Fusarium head blight (FHB) on wheat was conducted in 20 locations/fields annually in Al-Ghab plain, Syria during spring of three seasons (2008-2010).

Results showed variation in the infection rate of ears, disease severity and Fusarium infection index (FII) among locations and years, and averaged 3.4%, 4.96% and 0.44, respectively.

The annual infected fields' rate with the disease reached 56.5%, and the average of Fusarium diseased kernels was 0.29%, with highest infection rates recorded in the northwestern regions of Al-Ghab plain and the lowest in the southeastern regions.

Ten Fusarium species were associated with the disease complex based on the examination and classification of 240 single spore isolates obtained from glumes (114 isolates) and kernels (126 isolates), which represented infected fields.

Fusarium culmorum was the most frequent (43.8%), followed by F.

equiseti (23.3%), F.

moniliforme (14.6%), F.

proliferatum (7.1%), F.

sambucinum (2.9%), F.

compactum (2.1%), F.

solani (1.7%), F.

crookwellense (0.8%), F.

avenaceum (0.8%), and F.

semitectum (0.4%).

Saturated cotton ball with conidial suspension of the most frequent Fusarium species (F.

culmorum, F.

equiseti, F.

moniliforme and F.

proliferatum) was used for artificial inoculation of the spikes of wheat cultivars, Cham 3 and Bohouth 6.

The FII values were significantly higher than the FII values of the sperately sprayed treatments with the same species, during the same period.

The pathogenicity of the Fusarium species (114 isolates, represented 10 species) varied, depending on the specific infection index rate of isolates of each species, separately, on the spikes of both wheat cultivars, and using cotton ball saturated separately with conidial suspension of each isolate.

F.

culmorum and F.

moniliforme were characterized by high aggressiveness (FII > 70) on spikes of both cultivars, followed by F.

equiseti and F.

proliferatum, whose aggressiveness was moderate (FII ≤ 70 and > 40).

The aggressiveness F.

culmorum isolates on Cham 3 and Bohouth 6 were 75.0 and 78.1%, respectively.

Majority of F.

culmorum and F.

proliferatum isolates originated from infected kernels had higher aggressiveness on the ears of both wheat cultivars compared to isolates originated from glumes, and the reverse was observed for the F.

equiseti isolates.

However, in the case of F.

moniliforme isolates originated from kernels or from glumes were equally highly aggressive