Oomycetes from the genus Phytophthora are among the most important plant pathogens in agriculture. Epidemics caused by P. infestans precipitated the great Irish famine and had a major impact on society and human history. In the tropics, P. palmivora is a pathogen of many plant species including cacao (Theobroma cacao), citrus (Citrus sp.), durian (Durio zibethines), jackfruit (Artrocarpus heterophyllus), rubber (Hevea brasiliensis), and several palm species including coconut (Cocos nucifera), and the African oil palm (Elaeis guineensis) as determined recently. The first localized epidemics of bud rot in oil palm in Colombia were reported in 1964. However, recent epidemics of bud rot have destroyed more than 70,000 ha of oil palm in the Western and Central oil palm growing regions of Colombia. The agricultural, social, and economic implications of these outbreaks have been significant in Colombia. Identification of the pathogen after 100 years of investigating the disease in the world enabled further understanding of infection, expression of a range of symptoms, and epidemiology of the disease. This review examines the identification of P. palmivora as the cause of bud rot in Colombia, its epidemiology, and discusses the importance of P. palmivora as a major threat to oil palm plantings globally.

https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO-09-15-0243-RVW

Bud Rot Caused by Phytophthora palmivora: A Destructive Emerging Disease of Oil Palm

This paper is the second in a series focused on providing a stable platform for the taxonomy of phytopathogenic fungi. It focuses on 25 phytopathogenic genera: Alternaria, Bipolaris, Boeremia, Botryosphaeria, Calonectria, Coniella, Corticiaceae, Curvularia, Elsinoe, Entyloma, Erythricium, Fomitiporia, Fulviformes, Laetisaria, Limonomyces, Neofabraea, Neofusicoccum, Phaeoacremonium, Phellinotus, Phyllosticta, Plenodomus, Pseudopyricularia, Tilletia, Venturia and Waitea, using recent molecular data, up to date names and the latest taxonomic insights. For each genus a taxonomic background, diversity aspects, species identification and classification based on molecular phylogeny and recommended genetic markers are provided. In this study, varieties of the genus Boeremia have been elevated to species level. Botryosphaeria, Bipolaris, Curvularia, Neofusicoccum and Phyllosticta that were included in the One Stop Shop 1 paper are provided with updated entries, as many new species have been introduced to these genera.

One stop shop II: taxonomic update with molecular phylogeny for important phytopathogenic genera: 26–50 (2019)

The biocontrol by Streptomyces and Trichoderma of leaf spot disease caused by Curvularia oryzae in oil palm seedlings

Sugarcane (Saccharum officinarum) is one of the oldest crops cultivated by mankind. Numerous fungal taxa have been reported from this host, although most were not identified beyond genus level. In this study, we explored 31 sampling sites in Guangxi and Guangdong Provinces (China), and collected 370 diseased samples from leaves and roots of sugarcane, from which 762 strains were isolated. Our preliminary analysis based on internal transcribed spacer (ITS) sequences suggested that these isolates belonged to 143 species in 51 genera, but we could not assign 129 strains. Bipolaris, Chaetomium, Curvularia, Phoma and Nigrospora represented the top five most common genera identified, while 27 rare genera comprised only one identified species. In this study, we chose above mentioned common genera for in-depth morphological observations and multi-locus analyses, in order to identify these strains to species level. In this paper, we described one new genus, 32 new species, and reported 19 new records for China and the asexual morph of Chaetomium olivaceum. Hitherto, this is the most comprehensive study with molecular identification and illustration of fungi associated with sugarcane, which greatly improves our understanding of culturable mycota associated with this host.

Culturable plant pathogenic fungi associated with sugarcane in southern China

Input–output optimisation model for sustainable oil palm plantation development

A survey of diseases and disorders in oil palms of southern Thailand.

The causal agent of leaf spot disease of oil palm (Elaeis guineensis) seedling nurseries in Thailand was identified as Curvularia oryzae. The fungus was isolated from leaves with disease symptoms, characterized by morphological properties, and pathogenicity tested. The identity of the phytopathogenic fungus was confirmed through polymerase chain reaction analysis using internal transcribed spacer (ITS) primers, which amplified about a 1 kb product. Sequencing this DNA product confirmed this pathogen was C. oryzae. Furthermore, the pathogenicity test showed that C. oryzae could infect oil palm seedlings.

Disease note: identification of Curvularia oryzae as cause of leaf spot disease on oil palm seedlings in nurseries of Thailand.

Survey and incidence of leaf blight and leaf spot diseases of oil palm seedlings in Southern Thailand.

Leaf spot disease, particularly 'Curvularia' leaf spot (CLS), can devastatingly damage both quality and quantity of oil palm seedlings in Thailand. Chemical fungicides have been intensively applied to control transmission of this disease. However, this has relatively low efficiency as the causative pathogen gains resistance to fungicides with selection pressure. An alternative or complementary cost-effective and environmentally friendly approach is necessary to find the resistant varieties for disease management. In this present study, a total of 122 lines of Dura female plant, 2 lines of Pisifera male plant, and 4 Tenera commercial varieties (A, B, C and SUP-PSU1) were screened by 'Curvularia' inoculation using detached leaf method. Two weeks after inoculation, the results showed 13 Dura lines as highly resistant to CLS (0% disease incidence), whereas one line (129) and the commercial variety B were highly susceptible (100% disease incidence). Nine Tenera hybrid lines from 13 Dura highly resistant lines were selected to test for high resistance and subjected to 'Curvularia' inoculation in greenhouse conditions, and compared with the susceptible and highly susceptible lines. Three Tenera hybrid lines (138, 187 and 203) showed high resistance to CLS significant difference from susceptible lines. These were the most highly resistant varieties to CLS and should be considered for breeding programs of oil palm stock among the cases tested.

/pdf/screening-of-oil-palm-elaeis-guineensis-jacq-varieties-for-3gh4je9u89.pdf

Jittra Kittimorakul

Papers

A survey of diseases and disorders in oil palms of southern Thailand.

Disease note: identification of Curvularia oryzae as cause of leaf spot disease on oil palm seedlings in nurseries of Thailand.

Survey and incidence of leaf blight and leaf spot diseases of oil palm seedlings in Southern Thailand.

Screening of oil palm ('Elaeis guineensis' Jacq.) varieties for resistance to 'Curvularia' leaf spot disease