Biological Control of Phytophthora Root Rot of Pepper Using Trichoderma harzianum and Streptomyces rochei in Combination

Abstract

A combination of two compatible micro-organisms, Trichoderma harzianum and Streptomyces rochei, both antagonistic to the pathogen Phytophthora capsici, was used to control root rot in pepper. The population of the pathogen in soil was reduced by 75% as a result. Vegetative growth of the mycelium of P. capsici was inhibited in vitro on the second day after P. capsici and T. harzianum were placed on the opposite sides of the same Petri plate. Trichoderma harzianum was capable of not only arresting the spread of the pathogen from a distance, but also after invading the whole surface of the pathogen colony, sporulating over it. Scanning electron microscopy showed the hyphae of P. capsici surrounded by those of T. harzianum, their subsequent disintegration, and the eventual suppression of the pathogen's growth. Streptomyces rochei produced a zone of inhibition, from which was obtained a compound with antioomycete property secreted by the bacteria. When purified by high-pressure liquid chromatography, this compound was identified as 1-propanone, 1-(4-chlorophenyl), which seems to be one of the principal compounds involved in the antagonism. A formulation was prepared that maintained the compound's capacity to inhibit growth of the pathogen for up to 2 years when stored at room temperature in the laboratory on a mixture of plantation soil and vermiculite. The two antagonists, added as a compound formulation, were effective at pH from 3.5 to 5.6 at 23-30°C. The optimal dose of the antagonists in the compound formulation was 3.5 · 10 8 spores/ml of T. harzianum and 1.0 · 10 9 FCU/ml of S. rochei. This is the first report of a compound biocontrol formulation of these two antagonists with a potential to control root rot caused by P. capsici.

EFFECT OF MYCORRHIZAE AND ACTINOMYCETES ON GROWTH AND BIOPROTECTION OF Capsicum annuum L. AGAINST Phytophthora capsici

“…About the bioprotection promoted by actinomycetes against P. capsici, Ezziyyani et al (2004) demonstrated that Streptomyces rochei inhibited up to 81% of P. capsici radical growth in 4 days, while on day 7, the actinomycete was able to parasitize, promoting the production of mycelial degradative enzymes of the plant pathogen oomycete. Ezziyyani et al (2007) purified, from S. rochei, the compound 1 propane, 1-4 chlorophenyl with antagonistic capacity against this phytopathogen. There are very few studies on the application of actinomycetes in the biocontrol of diseases under plant conditions; however, recently, Goudjal et al (2014) found that application of a consortium of six actinomycetes coated in tomato seeds reduced, by up to 86.6%, the of incidence on the disease known as damping-off caused by Rhizoctonia solani in seedbeds with infested substrate.…”

Pythium oligandrum: an example of opportunistic success

“…In the last few years, several reports have shown that co-inoculation of beneficial microorganisms could stimulate plant growth and/or increase plant disease resistance relative to inoculation with a single biocontrol agent (Raimam et al, 2007;Whipps, 2004). Although such combinations may enhance the level of plant protection against pathogen attack (Ezziyyani et al, 2007;Guetsky et al, 2001Guetsky et al, , 2002, the possible competitiveness between these micro-organisms has to be taken into consideration (Alabouvette et al, 2006). …”

Cover Crop, Reflective Polyethylene Mulch and Biofungicide Effects on Yield and Management of Diseases in Field-Grown Organic Tomato

“…and other organisms is foremost in the biological control of many diseases and has helped minimize crop losses due to disease (Ezziyyani, Requena, Egea-Gilbert, & Candela, 2007;Jacobsen, Zidack, & Larson, 2004;Zehnder, Murphy, Sikora, & Kloepper, 2001). …”