Lizel Mostert

Olive anthracnose is an important disease in South Africa, which can result in high yield losses and reduced oil quality. This study aimed to identify the Colletotrichum species associated with olive anthracnose in South Africa, determine the in vitro efficacy of four fungicides against the fungi, and evaluate the susceptibility of newly bred olive lines to anthracnose. Olive fruit with typical anthracnose symptoms and twigs showing dieback were collected from olive farms in the Western Cape region. Isolations were made, and causal fungi were identified by amplification and sequencing of the internal transcribed spacers, partial β-tubulin and actin genes as well from their morphological characteristics. All isolates were identified as Colletotrichum acutatum sensu stricto. Fungicide sensitivity of mycelium growth and conidium germination were assessed for dodine, thiram and the mixtures of boscalid + pyraclostrobin and cyprodinil + fludioxinil. Mycelium growth and conidium germination of C. acutatum were strongly inhibited by boscalid + pyraclostrobin and cyprodinil + fludioxonil. The three most virulent C. acutatum isolates were assessed in a wounded fruit droplet inoculation trial on the olive cultivars Manzanilla (susceptible) and Mission (moderately susceptible). These isolates were also used to assess susceptibility of 18 newly bred olive lines and six reference cultivars. Unwounded fruit samples were dip inoculated with a mixture conidium suspension of the three C. acutatum isolates, and lesion development was recorded. Four potential oil lines and three green table olive lines showed resistance to the fungi. This study reports the first sequence confirmation of C. acutatum s.s. associated with anthracnose of olives in South Africa. Furthermore, the identification of the seven resistant olive lines enabled their selection for further evaluation and development. Fungicide sensitivity, together with newly bred line susceptibility results, will aid in development of integrated disease management for olive anthracnose.

Trunk disease (TD) fungi are taxonomically diverse, and accurate species delimitation relies on multilocus phylogenetic analyses. However, the loci commonly employed vary among fungal groups, leading to inconsistencies in species recognition. This paper provides a comparative overview of the most informative genetic loci for species identification within the main families associated with TDs, including Botryosphaeriaceae, Cytosporaceae, Diaporthaceae, Diatrypaceae, Phaeomoniellaceae, Togniniaceae, Nectriaceae (Ascomycota), and Hymenochaetales (Basidiomycota). The internal transcribed spacer region (ITS) remains the universal primary barcode, but its discriminatory power is often limited. The most informative loci [translation elongation factor 1-α (tef1), β-tubulin (tub2), actin (act1), calmodulin (cal), histone (his3), and the RNA polymerase II second largest subunit (rpb2)] are identified, and optimal locus combinations for each fungal group are identified. This synthesis will aid selection of the most appropriate loci for robust phylogenetic inference and accurate pathogen identification, thereby improving epidemiological and management studies of TDs.

BACKGROUND: Grapevine trunk diseases (GTDs) threaten vineyard longevity by reducing the yield and phytosanitary quality of propagation material from rootstock mother vines. The optimal age for replacing mother blocks to mitigate these risks is unclear. This study evaluated the effects of mother block age on the physiological, morphological, and infection status of mother vines and one‐year‐old canes produced by it. RESULTS: Cane morphology and physiology were highly variable, influenced by rootstock and season, with no consistent association with mother block age. Grapevine trunk disease incidence was widespread in mother vine heads, dominated by Celotheliaceae and Botryosphaeriaceae, with incidences up to 84‐90%. One‐year‐old canes generally showed lower infection rates, though Botryosphaeriaceae and Celotheliaceae reached 28% and 2%, with DNA concentrations up to 3171 and 1055 ng μL ⁻¹ , respectively. Diplodia seriata in mother vine heads directly contaminated one‐year‐old canes. Multivariate analyses revealed Botryosphaeriaceae negatively impacted cane morphology, Celotheliaceae and Diaporthaceae reduced starch content, and Botryosphaeriaceae and Hymenochaetaceae increased total phenolic index. CONCLUSION: Mother block age minimally influenced cane physiology or morphology. However, high GTD prevalence in mother vine heads poses systemic infection risks and reduces cane quality. Monitoring and management of GTD pathogens in rootstock mother blocks are essential to maintain the health and productivity of propagation material and ensure vineyard longevity. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Botryosphaeria canker and dieback is an important fungal disease caused by Botryosphaeriaceae spp. that affects the productivity of apple orchards in Chile and worldwide. In the field, studies on the management of this disease are focused on the protection provide by fungicides applied on pruning wounds. However, in Chile, information about the protection and efficacy of fungicides on apple trees against twig and branch pathogens is scarce. Therefore, in this study, we evaluated the efficacy of fungicides to control fungal trunk pathogens causing Botryosphaeria canker and dieback in apple trees using in vitro, greenhouse, and field trials. Isolates of Diplodia mutila, D. seriata, Neofusicoccum arbuti, and Lasiodiplodia theobromae obtained and characterized previously in Chile from apple trees with canker and dieback symptoms were used in this study. In vitro tests showed that benomyl, fluazinam, difenoconazole, and tebuconazole exhibited the lowest EC ₅₀ values, with means of 0.08, 0.09, 0.12, and 0.18 μg/ml, respectively. This study demonstrates that infection caused by D. mutila, D. seriata, L. theobromae, and N. arbuti can be significantly reduced using single-sprayed fungicides. The most effective in reducing infection on pruning wounds of apple trees by Botryosphaeriaceae were benomyl (66 to 76%), tebuconazole (47 to 68%), thiophanate-methyl (68 to 71%), boscalid + pyraclostrobin (47 to 63%), fluxapyroxad + pyraclostrobin (54 to 57%), and thiophanate-methyl + tetraconazole (63 to 74%). To our knowledge, this is the first study reporting the control of Botryosphaeriaceae causing canker and dieback in apple trees through the use of commercially available chemical fungicides, with different active ingredients and modes of action.

It is known that Trichoderma spp. can protect winter pruning wounds effectively against infection by trunk disease pathogens. Another port of entry for trunk disease pathogens is spring sucker wounds. Trichoderma spp. hold the potential to be applied to grapevine sucker wounds to prevent infection by trunk disease pathogens. During spring, fungicides are regularly applied to control grapevine foliar and fruit diseases. The effect of these fungicides on T. atroviride is unknown. The efficacy of a T. atroviride -based commercial product, Eco-77®, was tested on sucker wounds in a vineyard against the trunk pathogens Phaeomoniella chlamydospora and Diaporthe ampelina . Sucker wounds were made on one-year-old wood of Cabernet Sauvignon vines. The wounds were spray-treated with Eco-77® immediately after suckering, and 24 hours later the sucker wounds were inoculated with spore suspensions of either P. chlamydospora or D. ampelina . After five months, isolations were made from the sucker wounds. Trichoderma atroviride reduced the incidence of P. chlamydospora by 66.65%. Even though the incidence of D. ampelina was reduced by 15.37%, it was not significantly different from the control treatment. In vitro sensitivity studies were utilised to investigate the effect of fungicides applied during spring against other diseases (downy and powdery mildew, Botrytis rot and Phomopsis cane and leaf spot) on Trichoderma spp. The inhibition of mycelial growth and conidial germination of T. atroviride (UST1 and Eco-77®) was screened for 16 fungicides. Potato dextrose agar and broth were amended to obtain 0, 0.25, 0.5, 1 and 2 times the recommended dosages of the respective fungicides. Trichoderma spp. isolates were the least sensitive to the systemic fungicides boscalid, metrafenone and trifloxystrobin, as well as to the contact fungicides quinoxyfen and meptyldinocap for mycelial inhibition. These fungicides gave less than 50% mycelial inhibition at all the tested dosages. For the conidial germination assay, boscalid, penconazole and trifloxystrobin (systemic fungicides) gave less than 50% conidial germination inhibition of Trichoderma spp. Spiroxamine and pyrimethanil gave the highest mean percentage inhibition for both mycelial inhibition and conidial germination. The findings of this study show that T. atroviride can potentially be used to protect sucker wounds against P. chlamydospora . Furthermore, fungicides applied to grapevines during springtime can influence the conidial germination and mycelial growth of T. atroviride (UST1 and Eco-77®) to varying degrees. When applying Trichoderma spp. in spring, care needs to be taken in the timing of application of fungicides so as not to inhibit the growth of the biocontrol fungus.

Two cases of phaeohyphomycotic infections were caused by Phaeoacremonium tuscanicum, not previously identified in human infections, and one new species, Phaeoacremonium indicum, respectively. Morphological and cultural investigation as well as phylogenetic analysis was constructed based on maximum likelihood analyses using actin and -tubulin sequences to identify the fungal isolates.

Grapevine trunk disease fungi infect vines through openings, primarily pruning wounds. The main objective of this study was to understand the role of sucker wounds and wounds made by the removal of green shoots from the stems of potted grapevines as potential points of infection for grapevine trunk disease pathogens. Six wine and four table grape vineyards of different ages were sampled in different production areas in the Western Cape grape region of South Africa. Isolations were made from 161 sucker wounds, and fungal pathogens were identified using morphology and DNA sequence analysis of the internal transcribed spacers (ITS1 and ITS2) and the 5.8S ribosomal RNA gene, the translation elongation factor 1alpha or the partial β-tubulin gene. The results show that 62% of the sucker wounds were infected by trunk disease pathogens, including Diaporthe ampelina , Diplodia seriata , Phaeomoniella chlamydospora , Phaeoacremonium minimum , Eutypella microtheca , Cryptovalsa ampelina and Neofusicoccum australe . Diaporthe ampelina was the most common, followed by D. seriata and P. chlamydospora , in both the wine and table grape sucker wounds. Under glasshouse conditions, wounds made by the removal of young green shoots on one-year-old potted grapevine plants were inoculated with spore suspensions of D. ampelina , E. lata , N. parvum , P. minimum and P. chlamydospora . After four months, all the inoculated pathogens could be re-isolated. This study shows that grapevine sucker and green shoot wounds are susceptible to different grapevine trunk disease pathogens and may therefore play a role in the epidemiology of trunk diseases.

Honeybush (Cyclopia spp.) is an indigenous, leguminous member of the Cape fynbos biome growing in the coastal winter rainfall districts of the Western and Eastern Cape Provinces of South Africa (Jo...