Botryosphaeriaceae Research Articles

Botryosphaeriaceae associated with baobab (Adansonia digitata L.) and marula (Sclerocarya birrea A. Rich.) in agroforestry systems in Kenya

Indigenous fruit trees such as baobab and marula provide key nutrients and income for smallholders and enhance diversification of agroforestry systems in the drylands of Sub Saharan Africa. Cankers and diebacks are increasingly observed impacting baobab and marula in domestication trials and farms in Kenya, but little is known on disease occurrence and associated pathogens. Field disease incidence and severity was assessed. Fungal isolation and molecular identification was performed and pathogenicity of isolates was evaluated on baobab, marula and additional agroforestry trees. Nine taxa morphotypes belonging to genera Lasiodiplodia, Neofusicoccum and Dothiorella were identified co-occurring in both symptomatic and asymptomatic plant material. Seedlings inoculated with isolates of L. pseudotheobromae, L. theobromae and N. parvum showed similar symptoms with various degree of virulence. These findings suggest that species of Botryosphaeriaceae may occur as endophytes and also act as a disease complex, with the potential of infecting a wide range of trees in Eastern Kenya. Further investigation of ecology and impact of this potential threat to agroforestry systems in the African drylands, need to be performed in order to develop mitigation strategies. Key words: Adansonia digitata, agroforestry, Botryosphaeriaceae, Sclerocarya birrea, tree cankers.

Genetic diversity in Macrophomina phaseolina, the causal agent of charcoal rot.

Summary. Macrophomina phaseolina (Botryosphaeriaceae) is an important soil- and seed-borne pathogen. This pathogen has a broad geographic distribution, and a large host range. The aim of the present study was to determine the genetic variation among a global set of 189 isolates of M. phaseolina, isolated from 23 hosts and 30 soil samples in 15 countries. To achieve this goal a multi-gene DNA analysis was conducted for the following five loci, ITS, TEF, ACT, CAL and TUB. Based on these results two well-defined clusters could be delineated, one corresponding to M. phaseolina s. str., for which a suitable epitype is designated. The second clade corresponds to M. pseudophaseolina, a novel species occurring on Abelmoschus esculentus, Arachis hypogaea, Hibiscus sabdarifa and Vigna unguiculata in Senegal. No consistent correlation was found among genotype, host and geographic location, and both species could even occur on the same host at the same location. Although M. pseudophaseolina is presently only known from Senegal, further research is required to determine its virulence compared to M. phaseolina, and its geographic distribution.

Temporal conidial dispersal pattern of Botryosphaeriaceae species in table-grape vineyards in Northeastern Brazil

A field experiment was conducted between mid-August 2016 and mid-October 2017 in four table-grape vineyards in the Siriji Valley, Pernambuco State (Northeastern Brazil), to study the conidial dispersal dynamics of Botryosphaeriaceae fungi, causing grapevine trunk diseases (GTDs). Conidial dispersal was assessed by exposing microscope slides coated with Vaseline close to symptomatic plants and pruning debris. The slides were replaced every 2 weeks for a total of 30 sampling periods. Conidia of the genera Diplodia , Lasiodiplodia and Neofusicoccum were enumerated based on morphological characters. Conidia were collected from all four table-grape vineyards, confirming that these fungi are present as aerial inoculum and could be associated with GTDs in the region. Conidia of Diplodia and Lasiodiplodia were present in all the sampling periods, and those of Lasiodiplodia were the most abundant. Conidia of Neofusicoccum were found less frequently, and in less numbers than the other genera. Significant correlation between the number of conidia sampled and the amount of rain was observed for Diplodia only. Greater numbers of conidia were collected from pruning debris than from symptomatic plants. For Diplodia and Lasiodiplodia , the numbers of conidia gradually increased in September, increased sharply between March and June, and then decreased. These dynamics were described by a logistic equation, with hydro-thermal time (i.e., a combination of degree-days and relative humidity) as the independent variable ( R 2 > 0.998).

ISOLATION, IDENTIFICATION AND PATHOGENICITY OF BOTRYOSPHAERIACEAE AND PHAEOACREMONIUM SPECIES ASSOCIATED WITH DECLINE OF PRUNUS SPECIES IN IRAN

Between 2011 and 2013, a field survey was undertaken on stone fruit trees in four provinces of Iran to determine the fungal trunk pathogens associated with decline diseases. Wood samples were collected from branches of apricot, peach, cherry, sour cherry and greengage trees showing yellowing, dieback, defoliation, canker, gummosis, decline and internal wood discolouration. Five Phaeoacremonium species, including Phaeoacremonium minimum, P. parasiticum, P. viticola, P. tuscanum and P. krajdenii and six species of Botryosphaeriaceae, namely Diplodia seriata, D. mutila, Neofusicoccum parvum, Botryosphaeria dothidea, Spencermartinsia viticola and Lasiodiplodia theobromae, were isolated and identified based on morphology, culture characteristics and DNA sequence analyses. Pathogenicity tests of candidate fungi were conducted by artificially inoculating detached shoots of all host species with a pathogen-colonized agar plug then covered with Parafilm. 30 days post inoculation, the length of the necrotic wood lesions was measured. Neofusicoccum parvum was the most virulent among the six Botryosphaeriaceae species tested. Of Phaeoacremonium species, P. parasiticum produced the longest necrotic lesions on all inoculated hosts. The following are first reports from this study: (i) P. tuscanum on peach trees; (ii) L. theobromae, B. dothidea, and P. krajdenii on apricot trees; (iii) B. dothidea, S. viticola, D. seriata, D. mutila, P. parasiticum, P. viticola and P. minimum on cherry; (iv) D. seriata, P. minimum and P. parasiticum on sour cherry and (v) S. viticola, L. theobromae and D. seriata on greengage. Phaeoacremonium krajdenii has not yet been reported from Iran and the present study is the first report of this species in this country.

Mycosphere Essays 14: Assessing the aggressiveness of plant pathogenic Botryosphaeriaceae

Mycosphere Essays 14: Assessing the aggressiveness of plant pathogenic Botryosphaeriaceae

Dissemination of Botryosphaeriaceae conidia in vineyards in the semiarid Mediterranean climate of the Valparaíso region of Chile.

The dispersal of Botryosphaeriaceae conidia was studied in two vineyards in the Valparaiso Region of Chile, where semiarid Mediterranean climate conditions prevail. The objective of this study was to record trappings of Botryosphaeriaceae conidia over one year on a weekly basis and to associate these records with weather and agrochemical application data. Two Chardonnay vineyards in Casablanca and two Cabernet Sauvignon vineyards in Panquehue were selected. In each vineyard at each weekly sampling, five microscope slides covered with petroleum jelly (Vaseline) were installed near grapevines affected by Botryosphaeria cankers. In addition, Botryosphaeriaceae species associated with cankers in these vineyards were identified. Seasonal peaks of Botryosphaeriaceae conidia were detected among the different grape producing areas. In Casablanca, peaks of conidium dispersal were observed in winter 2013 and in autumn and winter 2014. Peaks of large numbers of conidia were mainly associated with precipitation events equal to or greater than 0.2 mm. The species observed in the spore traps were preliminarily identified as Diplodia seriata, Spencermartinsia viticola and Neofusicoccum sp., and isolations from adjacent plants confirmed the presence of D. seriata , S. viticola and N. australe in these vineyards. In Panquehue, peaks of conidium dispersal were observed in winter 2013, with a lower relative abundance of spores detected compared with Casablanca. Conidia dispersal recommenced in autumn 2014 but remained low later in winter. In this location, D. seriata was the main species detected, followed by S. viticola . No Neofusicoccum species was detected in this area. No association was found between conidium dispersal and the volume of water (≤ 1000 L ha -1 ) used in the application of agrochemical products.

First report of Neofusicoccum mangiferae associated with grapevine dieback in China.

The Botryosphaeriaceae represents an important, cosmopolitan family of pathogens infecting woody plants. Grapevines ( Vitis vinifera ) suspected of being affected by Botryosphaeria dieback were collected from different Provinces of China and several Botryosphaeriaceae species were identified. This research was conducted to further study the species of Botryosphaeriaceae associated with grapevines in China and to estimate the prevalence and severity of the disease. Symptoms were characterized by partial or total death of grapevine cordons, with brown U-shaped necrotic sectors and brownish-black spots in cross-sections of affected trunks and arms. A fungus isolated from diseased vines in Henan and Anhui Provinces was identified as Neofusicoccum mangiferae on the basis of its morphological and cultural characteristics as well as an analysis of combined sequence data from the internal transcribed spacer (ITS) cluster of the ribosomal DNA together with partial sequences of the β-tubulin (BT) and translation elongation factor (EF1-α) genes. Pathogenicity was assessed by inoculating the fungus onto detached green grapevine shoots under controlled laboratory conditions and mature wood of standing vines cv. Summer Black in a greenhouse. This is the first record of N. mangiferae associated with grapevine dieback in the world.

Splash dispersal of <i>Botryosphaeriaceae</i> species in Marlborough vineyards

Botryosphaeriaceae species cause dieback and canker in many woody hosts including grapevines with infection occurring when conidia are released during rainfall and splash borne to pruning and trimming wounds This study monitored dispersal of naturally released conidia of Botryosphaeriaceae species in three Marlborough vineyards with a Burkard spore trap and rain water traps Microscopic examination of the Burkard tape and trapped rain water confirmed the presence of Neofusicoccum and Diplodia spp Species were identified on tape and in rainwater with single stranded conformational polymorphism as N luteum N parvum/Nribis N australe D mutila and D seriata To determine conidium dispersal distances sporulating shoot lesions of N parvum isolate B2141 for which an isolate specific marker was developed were placed in one Marlborough vineyard before forecast rainfall periods The rainwater traps were set up around the sporulating lesions at 05 to 20 m in the direction of the prevailing wind and 05 to 5 m in three other directions After 2 days rain Neofusicoccum sp conidia were identified in the collected rainwater by microscope and with the isolate specific PCRRFLP (restriction fragment length polymorphism) for N parvum B2141 This isolate dispersed up to 10 m in the wind direction and up to 1 m in the other three directions

Phaeoacremonium and Botryosphaeriaceae species associated with cypress (Cupressus sempervirens L.) decline in Kerman province (Iran).

Common cypress ( Cupressus sempervirens L.) is an east Mediterranean plant element and one of four native conifers in Iran. During spring and summer of 2012, a field survey was carried out in different areas of Kerman province (south-eastern Iran) to study cypress decline diseases. Samples were collected from crowns, trunks and branches of cypress trees showing yellowing, dieback, canker, wilting of leaves and internal wood discoloration. Isolations were made from symptomatic wood tissues. Based on morphological and molecular characteristics, four species of Phaeoacremonium , namely Phaeoacremonium parasiticum , Pm. aleophilum , Pm. iranianum and Pm. rubrigenum , and two species of the Botryosphaeriaceae, Botryosphaeria dothidea and Neofusicoccum parvum , were isolated and identified. Pathogenicity tests were undertaken to determine the role of these species on 2-year-old potted cypress plants and green shoots of grapevine. Neofusicoccum parvum was more virulent than the other species and caused the largest lesions on both hosts. The fungi were re-isolated from margins of lesions and healthy tissue, thus completing Koch’s postulates. This is the first report of B. dothidea , N. parvum , Pm. aleophilum , Pm. rubrigenum and Pm. iranianum as pathogens on Mediterranean cypress trees.

First report of Neofusiccoccum vitifusiforme and presence of other Botryosphaeriaceae species associated with Botryosphaeria dieback of grapevine in Sicily (Italy)

Summary. Since 2007, when a grapevine decline caused by Lasiodiplodia theobromae was reported for the first time in Sicily, vines showing similar declining symptoms have been also found in other grape-growing areas of western and central Sicily. We report the result of a study on fungi associated with grapevine decline in Sicily, with particular regard to those belonging to the Botryosphaeriaceae . Four species were found to be associated with declining vines, namely Diplodia seriata , Lasiodiplodia sp., Neofusicoccum parvum and Neofusicoccum vitifusiforme , the latter species reported for the first time on Vitis vinifera in Italy.

The status of Botryosphaeriaceae species infecting grapevines.

Normal 0 MicrosoftInternetExplorer4 Normal 0 MicrosoftInternetExplorer4 Species in the Botryosphaeriaceae have a cosmopolitan distribution, and occur on a wide range of annual and perennial hosts including grapevines. To date, morphological and taxonomic studies, as well as analyses of nucleotide sequences of multiple genes, have allowed the identification of at least 21 different species in the Botryosphaeriaceae occurring in grapevines worldwide. Grapevine disease symptoms caused by members of this family include leaf spots, fruit rots, shoot dieback, bud necrosis, vascular discoloration of the wood, and perennial cankers, and their current status as pathogens is reviewed. Additionally, the disease name Botryosphaeria dieback is proposed here to describe the different grapevine trunk disease symptoms caused by species of Botryosphaeriaceae. Much has been written during the last decade about the association between species in the Botryosphaeriaceae and grapevine trunk diseases, which has contributed to a better understanding of the role that these fungal taxa play in grapevine diseases. Although virulence has been shown to vary between species and isolates of the same species in different countries, these fungi have become well-recognized as important grapevine pathogens worldwide. Latest and novel findings from studies conducted in different countries, on disease etiology and species distribution, epidemiology and biology are discussed. Much progress has been achieved in the development and implementation of novel diagnostic and detection techniques.Vineyard sanitation techniques, as well as chemical, biological, and cultural control strategies available at the present time to reduce the infection caused by botryosphaeriaceous fungi, are presented in this review.

Influence of water stress on Botryosphaeriaceae disease expression in grapevines.

Several species in Botryosphaeriaceae have been associated with grapevine trunk diseases. To evaluate the effect of water stress on infection of grapevines by Botryosphaeriaceae spp., 1-year-old Shiraz/101-14 Mgt nursery grapevine plants were planted in plastic potting bags and placed outdoors under shade netting. Five weeks after planting, vines were pruned and the pruning wounds inoculated with spore suspensions of Neofusicoccum australe , Neofusicoccum parvum , Lasiodiplodia theobroma e or Diplodia seriata . Control treatments consisted of applications of sterile water or a Trichoderma harzianum spore suspension. Stem inoculations were done by inserting a colonised or uncolonised agar plug into a wound made in each stem. Four different irrigation regimes were introduced 12 weeks after planting to simulate varying degrees of water stress. Measurements of stomatal conductance, photosynthetic rate and leaf spectrometry were made to monitor physiological stress. Eight months after inoculation, vines were uprooted and the root, shoot and plant mass of each vine determined. Lesions observed in the inoculated pruning wounds and stems were also measured. Vines subjected to the lowest irrigation regime were significantly smaller than optimally irrigated vines. Water stressed vines also had significantly lower photosynthetic rates and levels of stomatal conductance compared with vines receiving optimal irrigation, indicating that these plants experienced significantly higher levels of physiological stress. The mean lesion length was significantly longer in the pruning wounds and stems of plants subjected to the lowest irrigation regime, with lesion length declining linearly with increasing irrigation volume. These results clearly indicate that when a grapevine is exposed to water stress, colonisation and disease expression by Botryosphaeriaceae spp. are much more severe.

Evaluation of biocontrol agents for grapevine pruning wound protection against trunk pathogen infection.

Trunk diseases of grapevine are caused by numerous pathogens, including Eutypa lata , Phaeomoniella chlamydospora , and species of Botryosphaeriaceae (incl. Botryosphaeria and aggregate genera), Phomopsis and Phaeoacremonium . Since infections occur mainly through pruning wounds, that have been shown by previous research to stay susceptible for up to 16 weeks after pruning, long-term pruning wound protection is required for prevention of infection. This study evaluated several biocontrol agents against a range of trunk disease pathogens in dual plate laboratory trials to determine macroscopic and microscopic interactions. The biocontrol agents had a substantial effect on all the pathogens, with a wide range of macroscopic and microscopic interactions observed. The best performing biocontrol agents were tested in two field trials. Fresh pruning wounds were treated with benomyl, Trichoderma products (Biotricho®, Vinevax® and ECO 77®) and isolates (USPP-T1 and -T2, identified as T. atroviride ) and Bacillus subtilis . Seven days after treatment the pruning wounds were inoculated by spraying with spore suspensions of Neofusicoccum australe , N. parvum , Diplodia seriata , Lasiodiplodia theobromae , Eutypa lata , Phaeomoniella chlamydospora or Phomopsis viticola . Eight months after inoculation, the treatments were evaluated by isolation onto potato dextrose agar. The efficacy of the biocontrol agents was in most cases similar or superior to that observed for benomyl. Isolate USPP-T1, in particular, was very effective, reducing incidence of Ph. viticola , E. lata , Pa. chlamydospora , N. australe , N. parvum , D. seriata and L. theobromae by 69, 76, 77, 78, 80, 85 and 92%, respectively. This is the first report of biological protection of grapevine pruning wounds against this group of grapevine trunk disease pathogens.

Temporal susceptibility of grapevine pruning wounds to trunk pathogen infection in South African grapevines.

Grapevine trunk diseases, caused by a range of phytopathogenic fungi, represent a serious impediment to wine and table grape production wherever these crops are cultivated. Previous studies have shown that the distribution of these pathogens is influenced by climate and that they are associated with a variety of internal wood decay symptoms. Little was known, however, about the influence of climate on the disease symptomatology of the different pathogens in a specific area. To address this, a survey was conducted in 30 wine and table grape vineyards in summer, marginal and winter rainfall regions of South Africa. Apart from Eutypa lata , which occurred only in the winter rainfall region, Phaeomoniella chlamydospora , species of Phaeoacremonium , Botryosphaeriaceae and Phomopsis occurred in all regions surveyed. The incidence of the fungal genera and species associated with trunk disease varied between regions, with overlapping symptom profiles that differed based on the climatic region. These findings suggest that symptom-based disease diagnosis alone is unreliable and that distribution and symptomatology of grapevine trunk pathogens are strongly influenced by climatic conditions in a specific production region.

Characterisation of the fungi associated with esca diseased grapevines in South Africa

During the period from 2001 to 2008, grapevines showing foliar and/or internal symptoms of esca were collected from various grape-growing regions in South Africa. Isolations were made from typical internal wood symptoms associated with esca, and fungal isolates were characterized by cultural growth patterns, morphology and phylogenetic inference. The gene regions sequenced included the internal transcribed spacers and the 5.8S rRNA gene (ITS) for the basidiomycetes and Phomopsis isolates , the partial b-tubulin and actin genes for Phaeoacremonium isolates and the partial translation elongation 1-a gene and the ITS for the Botryosphaeriaceae isolates. The fungi identified included Phaeomoniella chlamydospora and six species of Phaeoacremonium including Pm. aleophilum , Pm. alvesii , Pm. parasiticum , Pm.iranianum , Pm. mortoniae and Pm. sicilianum , of which the latter three are reported for the first time in South Africa. The following taxa were also identified: Eutypa lata , Phomopsis viticola , Phomopsis theicola , Diaporthe ambigua , Diplodia seriata , Neofusicoccum australe and N. parvum . The basidiomycete isolates were distributed over ten well supported monophyletic clades among genera of the Hymenochaetales. Two of these clades could be identified as species of Fomitiporia and Phellinus .

Symptoms and fungi associated with esca in South African vineyards

In the past, only a few incidences of esca diseased grapevines were reported from the Slanghoekand Rawsonville areas of South Africa, with the damage believed to be of little importance so that the diseasehas not been studied in South Africa. In the present study, vines with internal or external symptoms of the esca disease complex were sampled from table, raisin and wine grape cultivars from 37 production areas inthe Western Cape, Northern Cape and Limpopo provinces of that country. Most vines were greater than 10years old, but younger vines (3 and 5 years old) were also found to be infected. External symptoms, includingdieback, tiger striped leaves, berry symptoms (shrivelling, insufficient colouring) and apoplexy, resembledthose found on grapevines in Europe and the USA, although the typical tiger stripe symptom was observedless frequently. The internal stem and trunk symptoms were similar to European symptoms, and includedwhite rot, black and brown wood streaking, brown necrosis within white rot, sectorial brown necrosis andbrown/red/margins next to decay, which often included back lines delimiting white decay. The fungi isolatedmostly from the white rot were basidiomycetes species (30.4%). Black and brown wood streaking was primarily caused by Phaeomoniella chlamydospora (45.4%). Brown necrosis within the white rot was linked to colonization by basidiomycetes (20.4%), Phaeoacremonium aleophilum (15.9%) and Pa. chlamydospora (13.6%). Phaeomoniella chlamydospora (20.8%) and Botryosphaeriaceae species (10.7%) were isolated the most fromthe sectorial brown necrosis and Pa. chlamydospora (29.1%) from the brown/red margins and black lines next to decay. Given the wide distribution of esca complex wood and foliar symptoms in the grape growing regions investigated, this disease should be considered as an important limiting factor in the productive lifespan of vineyards and the quality of produce from grapevine in South Africa.

Lipophilic phytotoxins produced by Neofusicoccum parvum, a grapevine canker agent.

Lipophilic phytotoxins produced by Neofusicoccum parvum , a Botryosphaeriaceae species pathogenic to grapevine, were isolated and identified by spectroscopic methods as (3 R ,4 R )-(-)-4-hydroxymellein, (3 R ,4 S )-(-)-4-hydroxymellein, isosclerone and tyrosol. When assayed for phytotoxicity on tomato plants, all four metabolites showed phytotoxic activity, with (3 R ,4 R )-(-)-4-hydroxymellein and isosclerone the most active. Isosclerone is reported for the first time as produced by a Botryosphaeriaceae species

Control of grapevine wood fungi in commercial nurseries

Summary. Previous surveys conducted in commercial nurseries found that different wood fungi, namely Cylindrocarpon spp., Botryosphaeriaceae, Phomopsis viticola and Phaeomoniella chlamydospora infect grapevine cuttings. Two fi eld trials were carried out to evaluate the effectiveness of cyprodinil + fl udioxonil, pyraclostrobin + metiram, fl udioxonil and cyprodinil to prevent or reduce natural infections caused by such fungi. Rootstock and scion cuttings were soaked in fungicidal suspensions for 50 min prior to grafting. After callusing, the grafted cuttings were planted in two commercial fi eld nurseries with and without a previous history of grapevine cultivation. After nine months in the nursery, the plants were uprooted and analysed for the incidence and severity of the wood fungi. Plants uprooted from the fi eld without a previous history of grapevine cultivation were generally less strongly infected by wood fungi. Under this condition, only the mixture cyprodinil + fl udioxonil simultaneously reduced the incidence of Cylindrocarpon and Botryosphaeriaceae fungi, as well as the severity of Cylindrocarpon infections. Treatments did not produce signifi cant differences in the incidence and severity of P. viticola, and Pa. chlamydospora. For plants grown in the fi eld with a grapevine history, all fungicides except cyprodinil signifi cantly reduced the incidence and severity of Cylindrocarpon fungi. Also, the incidence and severity of Botryosphaeriaceae pathogens were signifi cantly decreased both by cyprodinil + fl udioxonil and by cyprodinil. No signifi cant differences were noticed for P. viticola incidence and severity, and Pa. chlamydospora was not detected again. These results suggest that the practice of soaking grapevine cuttings in selected fungicides prior to grafting signifi cantly reduces Cylindrocarpon spp. and Botryosphaeriaceae infections, thus improving the quality of planting material.