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Trichoderma is a genus of filamentous fungi with several species widely studied and used as biological control agents (BCAs) in agriculture. With respect to fungal disease control, Trichoderma spp. can use different mechanisms of action, including mycoparasitism, antibiosis, competition and/or activation of plant defences. Armillaria spp. are the causal pathogens of Armillaria root rot (ARR) disease, which is widely distributed and of great economic and environmental importance in agriculture and forestry. ARR can be devastating to plant health, through colonisation and rotting of the root system and collar of the infected plant/tree, which can cause a reduction in yield and eventually death. Armillaria can live as a saprophyte that survives on dead plant material, making eradication of ARR extremely difficult. In an exhaustive analysis of work published to date on the control of Armillaria spp. by Trichoderma spp., using the WoS and Scopus databases, we identified 31 papers. We discuss these reports in light of their key findings, including number of publications per year, the countries where they were published, the journals and the citations obtained so far. Although the vast majority do not identify the mechanism of action involved in control, some describe mycoparasitism, antibiosis, competition or modification of the rhizospheric microbiota as being responsible for effective biological control of the pathogen. Further research into these mechanisms and additional in-depth analysis of less studied or currently unidentified mechanisms, such as the activation of plant defences, would be highly beneficial to our understanding of Trichoderma as a BCA of Armillaria.

Armillaria root rot (ARR) poses a significant threat to the long-term productivity of stone-fruit and nut crops in the predominant production area of the United States. To mitigate this issue, the development of ARR-resistant and horticulturally-acceptable rootstocks is a crucial step towards the maintenance of production sustainability. To date, genetic resistance to ARR has been found in exotic plum germplasm and a peach/plum hybrid rootstock, ’MP-29‘. However, the widely-used peach rootstock Guardian® is susceptible to the pathogen. To understand the molecular defense mechanisms involved in ARR resistance in Prunus rootstocks, transcriptomic analyses of one susceptible and two resistant Prunus spp. were performed using two causal agents of ARR, including Armillaria mellea and Desarmillaria tabescens. The results of in vitro co-culture experiments revealed that the two resistant genotypes showed different temporal response dynamics and fungus-specific responses, as seen in the genetic response. Gene expression analysis over time indicated an enrichment of defense-related ontologies, including glucosyltransferase activity, monooxygenase activity, glutathione transferase activity, and peroxidase activity. Differential gene expression and co-expression network analysis highlighted key hub genes involved in the sensing and enzymatic degradation of chitin, GSTs, oxidoreductases, transcription factors, and biochemical pathways likely involved in Armillaria resistance. These data provide valuable resources for the improvement of ARR resistance in Prunus rootstocks through breeding.

Abstract Peach is a popular and important tree fruit widely produced in the world, and the production of high-quality peach fruit does require management of pests and diseases. In this review, major peach diseases from China, Spain, and USA are described in detail for the benefit of producers, consultants, researchers, and other interested parties. Minor diseases of concern in these countries are also described. Current progress on pathogen resistance to major chemical classes of fungicides as well as current resistance management practices are discussed. Specific cultural practices applied in China, Spain, and USA are also described to provide an overview of peach disease management. A ‘Future Outlook’ section is included at the end of this review to highlight the challenges and opportunities for disease management in the future.

Armillaria root rot, one of the most dangerous diseases in our forests, is caused in Poland mainly by Armillaria ostoyae, especially severe in young Scots pine stands, established after broadleaved stands or with participation of broadleaved species. In Forest District Zielonka young stands are severly affected by Armillaria root rot. Only one species, A.ostoyae, was found in the young (8-14 yrs) Scots pine stands, despite the presence of other Armillaria species in the district. The pathogen's frequent occurrence may be due, inter alia, to favouring environmental factors.

During May 2010, sporocarps of what appeared to be an Armillaria sp. were found in large clumps in historic Kirstenbosch Botanical Gardens on the foot of Table Mountain, Cape Town, South Africa. These sporocarps could be physically linked to the roots of unidentified dead trees and Protea spp. The aim of this study was to identify the Armillaria sp. found fruiting in Kirstenbosch. To achieve this goal isolates were made from the mycelium under the bark of dead roots linked to sporocarps. The ITS and IGS-1 regions were sequenced and compared to sequences of Armillaria spp. available on GenBank. Cladograms were generated using ITS sequences to determine the phylogenetic relationship of the isolates with other Armillaria spp. Sequence comparisons and phylogenetic analyses showed that the isolates represented A. mellea. They were also identical to isolates of this species previously discovered in the Company Gardens in South Africa and introduced from Europe apparently by the early Dutch Settlers. Armillaria mellea is alien and apparently invasive in Cape Town, fruits profusely and has the potential to spread to sensitive native forests on the foothills of the City.