Many fungal diseases affect date palm causing considerable losses in date production worldwide. We found that the fungicide Cidely R Top inhibited the mycelial growth of the soil-borne pathogenic fungus Thielaviopsis punctulata, the... more
Many fungal diseases affect date palm causing considerable losses in date production
worldwide. We found that the fungicide Cidely
R Top inhibited the mycelial growth of the
soil-borne pathogenic fungus Thielaviopsis punctulata, the causal agent of black scorch
disease of date palm, both in vitro and in vivo. Because the use of biocontrol agents
(BCAs) can minimize the impact of pathogen control on economic and environmental
concerns related to chemical control, we aimed at testing local actinomycete strains
isolated from the rhizosphere soil of healthy date palm cultivated in the United Arab
Emirates (UAE) against T. punctulata. The selected isolate can thus be used as a
potential agent for integrated disease management programs. In general, the BCA
showed antagonism in vitro and in greenhouse experiments against this pathogen. The
most promising actinomycete isolate screened showed the highest efficacy against the
black scorch disease when applied before or at the same time of inoculation with T.
punctulata, compared with BCA or fungicide application after inoculation. The nucleotide
sequence and phylogenetic analyses using the 16S ribosomal RNA gene with other
Streptomyces spp. in addition to morphological and cultural characteristics revealed
that the isolated UAE strain belongs to Streptomyces globosus UAE1. The antagonistic
activity of S. globosus against T. punctulata, was associated with the production by this
strain of diffusible antifungal metabolites i.e., metabolites that can inhibit mycelial growth
of the pathogen. This was evident in the responses of the vegetative growth of pure
cultures of the pathogen when exposed to the culture filtrates of the BCA. Altogether,
the pathogenicity tests, disease severity indices and mode of action tests confirmed that
the BCA was not only capable of suppressing black scorch disease symptoms, but also
could prevent the spread of the pathogen, as a potential practical method to improve
disease management in the palm plantations. This is the first report of an actinomycete,
naturally occurring in the UAE with the potential for use as a BCA in the management of
the black scorch disease of date palms in the region.
worldwide. We found that the fungicide Cidely
R Top inhibited the mycelial growth of the
soil-borne pathogenic fungus Thielaviopsis punctulata, the causal agent of black scorch
disease of date palm, both in vitro and in vivo. Because the use of biocontrol agents
(BCAs) can minimize the impact of pathogen control on economic and environmental
concerns related to chemical control, we aimed at testing local actinomycete strains
isolated from the rhizosphere soil of healthy date palm cultivated in the United Arab
Emirates (UAE) against T. punctulata. The selected isolate can thus be used as a
potential agent for integrated disease management programs. In general, the BCA
showed antagonism in vitro and in greenhouse experiments against this pathogen. The
most promising actinomycete isolate screened showed the highest efficacy against the
black scorch disease when applied before or at the same time of inoculation with T.
punctulata, compared with BCA or fungicide application after inoculation. The nucleotide
sequence and phylogenetic analyses using the 16S ribosomal RNA gene with other
Streptomyces spp. in addition to morphological and cultural characteristics revealed
that the isolated UAE strain belongs to Streptomyces globosus UAE1. The antagonistic
activity of S. globosus against T. punctulata, was associated with the production by this
strain of diffusible antifungal metabolites i.e., metabolites that can inhibit mycelial growth
of the pathogen. This was evident in the responses of the vegetative growth of pure
cultures of the pathogen when exposed to the culture filtrates of the BCA. Altogether,
the pathogenicity tests, disease severity indices and mode of action tests confirmed that
the BCA was not only capable of suppressing black scorch disease symptoms, but also
could prevent the spread of the pathogen, as a potential practical method to improve
disease management in the palm plantations. This is the first report of an actinomycete,
naturally occurring in the UAE with the potential for use as a BCA in the management of
the black scorch disease of date palms in the region.
