Black Rot of Orchids Caused by Phytophthora cactorum and Phytophthora palmivora in Florida

Abstract

Several species of Phytophthora have been reported to cause economic damage on orchids worldwide. Of these, P. cactorum and P. palmivora have the widest host range across orchid genera, and they are the most common species affecting commercial orchid production in Florida. The objective of this guide is to provide a practical diagnostic resource for black rot on orchids in Florida. Accepted for publication 27 April 2010. Published 14 June 2010.

Biocontrol of Orchid-pathogenic Mold,Phytophthora palmivora, by Antifungal Proteins fromPseudomonas aeruginosaRS1

“…Fungal and mold pathogens cause several diseases in orchids, such as Curvularia lunata , causes rust spot disease on the flowers [ 23 ], C. eragrostidis causes rusty flower disease [ 24 ], Fusarium moniliforme causes column blight disease, Fusarium solani causes leaf yellowing and root and collar rot diseases [ 25 ], Fusarium oxysporum causes wilt disease, Sclerotium rolfsii causes collar rot disease, Phoma exigua causes flower spot disease, Colletotrichum gloeosporioides causes anthracnose disease [ 26 ], and Phytophthora palmivora causes black rot disease [ 23 ]. P. palmivora is considered a water mold that causes black rot disease in wide variety of orchids including Aerides , Ascocenda , Brassavola , Dendrobium , Gongora , Maxillaria , Miltonia , Oncidium , Paphiopedilum , Phalaenopsis , Rhynchostylis , and Schomburgkia [ 27 ]. After infection, orchids initially display small black lesions on the root or basal portion of the pseudobulbs, afterwards the black lesions expand to completely cover the pseudobulbs and leaves [ 27 ].…”

“…P. palmivora is considered a water mold that causes black rot disease in wide variety of orchids including Aerides , Ascocenda , Brassavola , Dendrobium , Gongora , Maxillaria , Miltonia , Oncidium , Paphiopedilum , Phalaenopsis , Rhynchostylis , and Schomburgkia [ 27 ]. After infection, orchids initially display small black lesions on the root or basal portion of the pseudobulbs, afterwards the black lesions expand to completely cover the pseudobulbs and leaves [ 27 ]. The mold spreads and infects other parts of the orchid until the orchid dies.…”

Antagonistic activity of endo‐β‐1,3‐glucanase from a novel isolate, Streptomyces sp. 9X166, against black rot in orchids

“…Quality management and disease control are important for the production of high‐quality orchids. Black rot is one of the most serious orchid diseases, and can be caused by several pathogens including Phytophthora cactorum and Phytophthora palmivora . Phytophthora is a genus of plant‐damaging oomycetes (water molds); their cell walls are composed of 1,3‐β‐glucans and some other β‐linked glucose polymers which comprise up to 90% of the dry weight .…”

“…After the pathogen infects an orchid, symptoms appear in the form of small black lesions; as the lesions age, they become enlarged, and the pathogen can spread through every part of the orchid. Eventually, the entire plant will be killed . At the present time, orchid growers typically use chemical pesticides such as fosetyl‐Al, potassium phosphite, propamocarb hydrochloride, and Terrazole 35% to control this disease.…”

Cultural characteristics and pathogenicity analysis of Phytophthora palmivora, causal pathogen of black rot in orchids

“…And because it is a thermophilic species, the hot environmental conditions such as in Thailand are favorable for its development [5]. The pathogen can spread throughout the rhizomes, causing rapid plant death [9], [10].…”