Molecular Identification and Disease Management of Date Palm Sudden Decline Syndrome in the United Arab Emirates.

Date palm orchards suffer from serious diseases, including sudden decline syndrome (SDS). External symptoms were characterized by whitening on one side of the rachis, progressing from the base to the apex of the leaf until the whole leaf dies; while the internal disease symptoms included reddish roots and highly colored vascular bundles causing wilting and death of the tree. Although three spp. (, and ) were isolated from diseased root samples, the fungal pathogen was associated with SDS on date palm in the United Arab Emirates (UAE). spp. were identified based on their cultural and morphological characteristics. The internal transcribed spacer regions and large subunit of the ribosomal RNA (ITS/LSU rRNA) gene complex of the pathogens was further sequenced. Pathogenicity assays and disease severity indices confirm the main causal agent of SDS on date palm in the UAE is . Application of Cidely Top (difenoconazole and cyflufenamid) significantly inhibited the fungal mycelial growth in vitro and reduced SDS development on date palm seedlings pre-inoculated with under greenhouse conditions. This is the first report confirming that the chemical fungicide Cidely Top is strongly effective against SDS on date palm.