First report of Teratosphaeria zuluensis causing stem canker of Eucalyptus grandis in Uganda

Teratosphaeria stem canker is one of the most important diseases to have emerged on nonnative plantation-grown Eucalyptus trees globally. In 2012, Eucalyptus grandis trees with typical Teratosphaeria stem canker symptoms were observed in Uganda. Multi-gene sequence analyses of isolates made from these cankers led to the identification of two species of Teratosphaeria on these trees. These were T. gauchensis, previously recorded in Uganda and T. zuluensis. This study represents the first report of T. zuluensis in Uganda. Furthermore, this is the first report of the co-occurrence of T. zuluensis and T. gauchensis in a single area.National Research Foundation (NRF), members of the Tree Protection Cooperative Programme (TPCP) and the THRIP Initiative of the Department of Trade and Industry, South Africa.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-0329hb201

Diseases on Eucalyptus species in Zimbabwean plantations and woodlots

Zimbabwe embarked on planting Eucalyptus species in the early 1900’s. Based on a robust breeding programme, it has become a major source of seed for other countries in and outside Africa. Tree health surveys conducted on Eucalyptus in some east and southern Africa countries over the past two decades have revealed several important fungal diseases that were previously not known in the region, but little is known regarding these problems in Zimbabwe. The aim of this study was to identify important eucalypt diseases across Zimbabwe’s agro-climatic regions. Morphological characteristics and DNA sequence data were used to identify pathogens collected to species level. Widespread stem canker diseases, caused by species belonging to the Botryosphaeriaceae and Teratosphaeriaceae, and leaf spot diseases caused by fungi in the Capnodiales, were identified. Armillaria root and stem rot was restricted to a single site in the Eastern Highlands. Fungi that could cause canker or blue stain of timber were isolated from recently harvested stumps and included species of Ceratocystis and Ophiostoma. This study is the first to identify Eucalyptus pathogens to species level in Zimbabwe and we report for the first time the presence of the stem canker pathogen T.gauchensis in southern Africa. The results will provide a foundation for the formulation of future disease management strategies in the country.National Research Foundation (NRF), members of the Tree Protection Cooperative Programme (TPCP) and the THRIP Initiative of the Department of Trade and Industry, South Africa.http://www.tandfonline.com/loi/tsed202016-06-30hb201

The Eucalyptus stem canker pathogen Teratosphaeria gauchensis represents distinct genetic groups in Africa and South America

Teratosphaeria gauchensis (Capnodiales) causes a serious stem canker disease on commercially propagated Eucalyptus species in South America. Recently, this pathogen was detected for the first time in Africa. Very little is known regarding the biology or origin of T. gauchensis, but it has been suggested that it is native to South America. The aim of this study was to compare isolates from Africa and South America using microsatellite markers. Bayesian analysis conducted in STRUCTURE, principal coordinates analysis and a UPGMA dendrogram revealed two distinct genetic groups for these isolates. The South American isolates were more genetically diverse than those from Africa. Patterns of genetic diversity in Africa suggest that T. gauchensis could have been introduced into Zimbabwe before spreading north-eastwards. The existence of the two genetic groups and high haplotype richness associated with the South American and Zimbabwean populations suggest that it will be more difficult to reduce the impact of disease caused by T. gauchensis in these regions than in those areas where there is limited genetic diversity.The National Research Foundation of South Africa (Grant specific unique reference number (UID83924), the members of the Tree Protection Co-operative Program (TPCP), the THRIP initiative of the Department of Trade and Industry and the DST/ NRF Centre of Excellence in Tree Health Biotechnology (CTHB).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-03292017-06-30hb2016Microbiology and Plant Patholog

First report of Teratosphaeria gauchensis causing stem canker of Eucalyptus in Kenya

Teratosphaeria stem canker is an important disease of Eucalyptus species in many parts of the world where these trees are intensively propagated in plantations. Symptoms similar to those of Teratosphaeria stem canker were observed on Eucalyptus grandis and a E. grandis x E. camaldulensis hybrid clone in the Central Highlands of Kenya. Symptomatic bark samples were collected from two sites and the associated fungus isolated and identified using DNA sequence analyses of multiple gene regions. The pathogen was identified as Teratosphaeria gauchensis. This represents the first report of the disease and the pathogen in Kenya.Tree Protection Co-operative Program (TPCP), the THRIP initiative of the Department of Trade and Industry, the DST/NRF Centre of Excellence in Tree Health Biotechnology (CTHB) of the Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, South Africa and the Kenya Forestry Research Institute (KEFRI).http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-03292017-04-30hb2016Forestry and Agricultural Biotechnology Institute (FABI)Microbiology and Plant PathologyPlant Production and Soil SciencePlant Scienc

Evaluation of water productivity, stover feed quality and farmers' preferences on sweet sorghum cultivar types in the semi-arid regions of Zimbabwe

Summary Twenty sweet sorghum cultivars that included 17 improved cultivars (experimental grain, forage, dual and India released varieties) from India and 3 landraces from southern Africa were evaluated for their use as an alternative food and fodder crop for crop-livestock farmers. The trials were conducted during 2007/08 season in semi-arid conditions at Matopos Research Station, Zimbabwe. Three methods of assessment were applied to help identify suitable cultivars: grain and stover water productivity (WP), stover feed quality traits and farmers' assessment of cultivars in the field. Grain and stover WP ranged from 0.6 to 2.7 kg m -3 and 1.2 to 4.0 kg m -3 respectively. We observed significant differences in cultivar groups on plant height, time to maturity, harvest index, grain WP, nitrogen uptake, nitrogen harvest index and stover metabolizable energy and digestibility (P <0.001), and sugar (Brix %) and stover WP (P <0.05). In the improved grain and dual type cultivars, grain yield increased by 118% compared to landraces and by 69% over the forage type while in the India released variety type cultivars grain yield increased by 86% compared to landrace yields and by 44% over the forage cultivars with an increase in stover yield. The landrace type was superior to all sweet sorghum types on feed quality traits (metabolizable energy and digestibility). The farmers' assessment demonstrated the need to combine qualitative and quantitative screening methods. The farmers' combined analysis showed that forage and grain yield are important parameters to the farmers following crop-livestock production systems. Results of the three methods showed that the dual type SP1411 was the preferred cultivar. Future breeding activities should therefore be directed towards the tradeoff between grain yield potential and stover feed quality in the quest for developing a wider range of dual purpose cultivars

Evaluation of water productivity, stover feed quality and farmers’ preferences on sweet sorghum cultivar types in the semi-arid regions of Zimbabwe

Twenty sweet sorghum cultivars that included 17 improved cultivars (experimental grain, forage, dual and India released varieties) from India and 3 landraces from southern Africa were evaluated for their use as an alternative food and fodder crop for crop-livestock farmers. The trials were conducted during 2007/08 season in semi-arid conditions at Matopos Research Station, Zimbabwe. Three methods of assessment were applied to help identify suitable cultivars: grain and stover water productivity (WP), stover feed quality traits and farmers’ assessment of cultivars in the field. Grain and stover WP ranged from 0.6 to 2.7 kg m-3 and 1.2 to 4.0 kg m-3 respectively. We observed significant differences in cultivar groups on plant height, time to maturity, harvest index, grain WP, nitrogen uptake, nitrogen harvest index and stover metabolizable energy and digestibility (P <0.001), and sugar (Brix %) and stover WP (P <0.05). In the improved grain and dual type cultivars, grain yield increased by 118% compared to landraces and by 69% over the forage type while in the India released variety type cultivars grain yield increased by 86% compared to landrace yields and by 44% over the forage cultivars with an increase in stover yield. The landrace type was superior to all sweet sorghum types on feed quality traits (metabolizable energy and digestibility). The farmers’ assessment demonstrated the need to combine qualitative and quantitative screening methods. The farmers’ combined analysis showed that forage and grain yield are important parameters to the farmers following crop-livestock production systems. Results of the three methods showed that the dual type SP1411 was the preferred cultivar. Future breeding activities should therefore be directed towards the tradeoff trade off between grain yield potential and stover feed quality in the quest for developing a wider range of dual purpose cultivars

Paleogene Radiation of a Plant Pathogenic Mushroom

Background: The global movement and speciation of fungal plant pathogens is important, especially because of the economic losses they cause and the ease with which they are able to spread across large areas. Understanding the biogeography and origin of these plant pathogens can provide insights regarding their dispersal and current day distribution. We tested the hypothesis of a Gondwanan origin of the plant pathogenic mushroom genus Armillaria and the currently accepted premise that vicariance accounts for the extant distribution of the species. Methods: The phylogeny of a selection of Armillaria species was reconstructed based on Maximum Parsimony (MP), Maximum Likelihood (ML) and Bayesian Inference (BI). A timeline was then placed on the divergence of lineages using a Bayesian relaxed molecular clock approach. Results: Phylogenetic analyses of sequenced data for three combined nuclear regions provided strong support for three major geographically defined clades: Holarctic, South American-Australasian and African. Molecular dating placed the initial radiation of the genus at 54 million years ago within the Early Paleogene, postdating the tectonic break-up of Gondwana. Conclusions: The distribution of extant Armillaria species is the result of ancient long-distance dispersal rather than vicariance due to continental drift. As these finding are contrary to most prior vicariance hypotheses for fungi, our result

Pre-harvest spoilage of avocado (Persea americana) fruits by Capnodium isolates in Zimbabwe

Thirteen fungal isolates associated with pre-harvest spoilage of avocado fruits were isolated on potato dextrose agar by incubating the infected avocado fruit tissue segments at 25 oC for 7 days. Three types of fungi were isolated from the infected tissue namely Glomerella cingulata (Stonem.), Aureobasidum pullulans (De Bary) and Capnodium sp. (Mont.). Capnodium sp. had the highest frequency (90.9 %) while only a single isolate was isolated for Aureobasidium pullulans. Pathogenicity tests using avocado fruits showed that Capnodium and Glomerella cingulata isolates caused soft rot symptoms similar to those observed on infected avocado fruits on the tree. Capnodium isolates gave the highest lesion diameter (3.0-7.1 cm) while Aureobasidium pullulans did not cause any lesion or soft rot symptoms on inoculated avocados. Although avocados are known to be hosts to Capnodium sp., in Zimbabwe, this is the first report implicating Capnodium sp. in the pre-harvest spoilage of avocado fruits. Preliminary studies show that Capnodium isolates produce cell wall degrading enzymes especially pectic and cellulolytic enzymes which are known to play a major role in most soft rot diseases.Keywords: Capnodium, sooty mould, pre-harvest spoilage, pathogenicit