Evaluation of certain Penicillium frequentans isolates against Cercospora leaf spot disease of sugar beet

Mansour M El-Fawy,Rafeek M I El-Sharkawy,Kamal A M Abo-Elyousr

doi:10.1186/s41938-018-0053-0

Mansour M El-Fawy, Rafeek M I El-Sharkawy + Show 1 more

Open Access

https://doi.org/10.1186/s41938-018-0053-0

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Abstract

The impact of six local isolates of Penicillium frequentans recovered from healthy sugar beet (Beta vulgaris L.) leaves was evaluated against Cercospora beticola, the causal pathogen of Cercospora sugar beet leaf spot under laboratory and field conditions. In in vitro studies, all the six isolates were able to inhibit the mycelial growth of C. beticola with variation in their antagonistic capability. P. frequentans isolates produce pectinase and cellulase at different degrees. There was a correlation between enzyme activity and the antagonistic ability for each isolate. The high antagonistic ability isolates had the most enzyme activity. In field studies, some adhesives such as agar, starch flour, white glue, gum, and commercial adhesive (Triton Mok) were added to conidia spore suspensions of P. frequentans at 1% to improve conidial adhesion to sugar beet plant surface. Data also showed that all adhesives increased (P = 0.05) the efficiency of the spore suspension of P. frequentans to control the disease. The starch flour at 1% gave a significant reduction in disease severity from 43.23 to 10.42% pre-infection and from 43.23 to 10.52% post-infection. The application of P. frequentans led to improved root yield and the sugar percent of sugar beet crop in two tested seasons.

Highlights

Cercospora leaf spot caused by Cercospora beticola is the most destructive leaf disease of sugar beet in all production areas (Piszczek et al 2017)
Isolation and identification of fungal isolates The fungal isolates were identified as P. frequentans according to their morphological and microscopic characteristics of conidia spores (Pitt 1979) and confirmed by Assiut University Mycological Center (AUMC)
The pathogenicity of P. frequentans isolates was tested on different species of plants, i.e., sugar beet, table beet, turnip, spinach, Swiss chard, and radish under greenhouse conditions to determine the pathogenic capability of the fungal isolates

Summary

Introduction

Cercospora leaf spot caused by Cercospora beticola is the most destructive leaf disease of sugar beet in all production areas (Piszczek et al 2017). The genus of Penicillium has major importance in the natural environment as well as food and drug production (Ropars et al 2014). Carlton et al (1976) reported that Penicillium species have been suppressing the bacterial growth in a number of studies. A much diversified array of active secondary metabolites, including potent mycotoxins (Frisvad and Samson 2004) and antibacterial (Rancic et al 2006; Lucas et al 2007) and antifungal substances (Nicoletti et al 2007).

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