Root-lesion nematodes, particularly Pratylenchus neglectus and P. crenatus (PNC), are widely distributed in New Zealand and cause significant damage to maize roots, reducing crop productivity. Despite their economic importance, no comprehensive assessment of commercial maize hybrids' resistance to PNC has been conducted in the country. Significant variation was observed in the nematode reproduction factor (Rf) and final population (Pf) among hybrids. In Experiment 1 (initial population (Pi) = 1250 PNC kg(-)(1) soil), Rf ranged from 3.1 in hybrid P8500 to 7.1 in hybrid P9127, with Pf values ranging from 3863 to 8903 PNC kg(-)(1) soil + roots in 45 days. In Experiment 2 (Pi = 750 PNC kg(-)(1) soil), Rf ranged from 18.4 in hybrid P1613 to 37.5 in hybrid P8805, with Pf values from 13,784 to 28,426 PNC kg(-)(1) soil + roots in 60 days. These results indicate active nematode reproduction and substantial hybrid-dependent variation in host response. Experiment 3 examined the impact of varying initial inoculum densities (500, 1000 and 1500 PNC kg(-)(1) soil), showing a dose-dependent increase in Pf and corresponding root damage. Susceptible hybrid (P9127) exhibited up to 42% root dry weight and 22% shoot dry weight reductions. This study is the first systematic evaluation of PNC resistance in New Zealand maize hybrids. It identifies P9127 and P8805 as highly susceptible, and P0891, P8500, and P1613 as moderately resistant. These findings offer valuable benchmarks for future breeding and support nematode management in New Zealand.
Asbestos is a silicate mineral that occurs naturally and is made up of flexible fibres that are resistant to heat, fire, and chemicals and do not conduct electricity. Both anthropogenic disturbance and natural weathering of asbestos-containing waste materials (ACWMs) can result in the emission of asbestos fibre dust, which when breathed, can cause asbestosis, a chronic lung illness that happens due to prolonged exposure of such fibre dust, and can cause 'mesothelioma' cancer. Although asbestos mining and its utilisation had been banned in many countries, there is still a significant issue of ACWMs disposal in the built environment and abandoned sites. It is neither practical nor economical to safely eliminate ACWMs from the built environment, and it is estimated that globally, 4 billion metric tonnes of ACWMs require safe management strategies. The toxicity of inhaled asbestos fibre relies on its surface properties, and in particular the distribution of iron, which serves a critical role in pathogenicity by forming reactive free radicals that damage DNA, thereby trigging cancer. Examining the usefulness of higher plants and microbes in the bioremediation of soil contaminated with ACWMs is the prime aim of the review. Higher plants and microorganisms such as lichens, fungi, and bacteria often play a major role in the remediation of soil contaminated with ACWMs by facilitating the bioweathering of asbestos and the removal of iron to mitigate the toxicity of asbestos.
Cassava root rot is a highly destructive disease that causes great damage in Brazil. Identification of the causal agents is essential for the management of this disease. Roots of cassava plants (Manihot esculenta Crantz) with symptoms of root rot were collected from a cassava crop in the municipality of Garanhuns, Pernambuco State, Brazil. This study aimed to identify a Diaporthe species isolated from cassava root rot in Brazil and evaluate pathogenicity in cassava plants and roots. At 7 days after inoculation (DAI), tuberous roots showed necrotic lesions, a soft appearance, and pink color in the center and brown to greenish at the edges, while seedlings showed root rot, wilting, yellowing, drying out, and leaf fall at 66 DAI in the soil. All plants in the control group were asymptomatic. After reisolations and confirmation of Koch's postulates, the causal agent was conclusively identified as Diaporthe ueckeri through the multilocus phylogenetic analyses involving the ITS, TEF1-alpha, TUB2, CAL, and HIS genes. The results showed that the morphological characteristics, such as colonies with abundant aerial mycelium, formation of pycnidia and alpha conidia, were consistent with those described for species of the genus Diaporthe. This is the first report of D. ueckeri causing cassava root rot in Brazil and worldwide.
Urban forest trees are vital components of urban ecosystems, offering a range of benefits that are essential for improving the livability and sustainability of cities, providing numerous advantages for both the environment and public health. They enhance air quality by filtering pollutants, assist in regulating urban temperatures, and alleviate the urban heat island effect, which can result in substantial energy savings. Trees are often vulnerable to pathogens and pests that can cause significant damage. A survey of different trees in five provinces of Iran revealed a severe decline and dieback disease on woody plants. The affected trees included ailanthus, cedrus, cypress, ash, haloxylon, walnut, magnolia, black mulberry, paulownia, pine, oriental plane, apricot, wild pear, and elm trees. Samples of symptomatic branches and trunks were collected, and the causal fungal pathogen was isolated on potato dextrose agar (PDA) media. A total of 90 fungal isolates were obtained from trees (60 isolates) and insects (30 isolates) and then morphological investigations were done for all isolates. Molecular identification was confirmed through sequencing of the ITS and tub2 regions. This study reports 14 new hosts for Paecilomyces formosus in Iran and worldwide. Pathogenicity tests were conducted on detached branches of apricot, ailanthus, cypress, pine, sycamore, and walnut trees. The study showed that most isolates were pathogenic to six woody plants, and some isolates were associated with disease for eight woody plant species. Additionally, potential vectors and reservoirs for P. formosus were assessed in different beetles, including Aeolesthes sarta, Scolytus kirschii, and Orthotomicus erusus in Tehran, Alborz, Qazvin, Lorestan, and Zanjan Provinces. The results confirmed the potential of beetles for the transmission and maintenance of P. formosus.
Soilborne fungal pathogens that cause root rot, wilting and dying are the most important problems in pistachio production. The purpose of this study was to examine, isolate, and diagnose the pathogens from diseased pistachio trees in orchards and nurseries located in southeastern Turkey. Fungi isolated from the pistachio trees were identified by morphology and the sequences of the internal transcribed spacer (ITS) region and translation elongation factor-1 alpha (TEF-1 alpha). Fusarium solani, Fusarium oxysporum, Fusarium brachygibbosum, Fusarium chlamydosporum and Macrophomina phaseolina were the most important fungi causing root rot, wilting and decline of pistachio trees. Pathogenicity studies showed that all of the fungi identified can colonize and damage the vascular tissues of a sapling and cause substantial lesions and vascular discolourations. This study provides the first evidence of wilting due to the root and crown rot in pistachio trees in Siirt province of Turkey caused by some Fusarium species, especially F. solani, F. oxysporum, F. chlamydosporum, F. brachygibbosum and M. phaseolina. Finally, the research enabled the identification of some fungal pathogens that are seriously harming pistachio trees in southeastern Turkey.
Alfalfa spring black stem and leaf spot disease (ASBS) is a cosmopolitan soil-borne and seed-borne disease caused by Phoma medicaginis, which adversely affects the yield, and nutritive value and can stimulate production of phyto-oestrogenic compounds at levels that may adversely affect ovulation rates in animals. This review summarizes the host range, damage, and symptoms of this disease, and general features of the infection cycle, epidemic occurrence, and disease management. ASBS has been reported from over 40 countries, and often causes severe yield loss. Under greenhouse conditions, reported yield loss was 31-82% for roots, 32-80% for leaves, 21% for stems and 26-28% for seedlings. In field conditions, the forage yield loss is up to 56%, indicating that a single-cut yield of 5302 kg/ha would be reduced to 2347 kg/ha. P. medicaginis can infect up to 50 species of plants, including the genera Medicago, Trifolium, Melilotus, and Vicia. ASBS is more severe during warm spring conditions before the first harvest than in hot summer and cooler winter conditions, and can infect alfalfa roots, stems, leaves, flowers, pods, and seeds, with leaf spot and/or black stem being the most typical symptoms. The primary infection is caused by the overwintering spores and mycelia in the soil, and on seeds and the cortex of dead and dry stems. The use of resistant cultivars is the most economical and effective strategy for the control of ASBS. Although biological control has been studied in the glasshouse and is promising, chemical control is the main control method in agriculture.
Agroathelia rolfsii (anamorph: Sclerotium rolfsii) is a soilborne fungal pathogen that can cause disease on over 500 documented host species, including economically important field and vegetable crops. The pathogen commonly infects the stem or crown of most hosts, but it is also capable of damaging fruit and root structures that are near the soil line, resulting in wilting, stunting, and plant death. Two diseases caused by this pathogen are sclerotial blight and circular spot, both of which are detrimental for sweetpotato production. A. rolfsii is a necrotrophic pathogen and can be cultured from susceptible hosts and on artificial media. The purpose of this diagnostic guide is to provide characteristic traits for identifying A. rolfsii in sweetpotato as well as outline methods for pathogen isolation, morphological and molecular characterization, culture maintenance and long-term storage, and pathogenicity testing.
We assessed the potentially pathogenic fungi present in Antarctic permafrost and the overlying active layer on King George, Robert, Livingston and Deception Islands in the South Shetland Islands archipelago, maritime Antarctica. Permafrost and active layer sub-samples were incubated at 37 & DEG;C to select fungi able to grow inside the human body. A total of 67 fungal isolates were obtained, 27 from the permafrost and 40 from the active layer. These represented 18 taxa of the genera Alternaria, Aspergillus, Curvularia, Penicillium, Rhodotorula and Talaromyces. The majority of fungi detected occurred exclusively either in the permafrost or the active layer at each site. Only Aspergillus thermomutatus, Penicillium cf. chrysogenum and Rhodotorula cf. mucilaginosa were present in both permafrost and active layer samples from the same site. The yeast R. cf. mucilaginosa was recovered from both in at least two sites. The genus Penicillium was the most abundant and widely distributed genus in both permafrost and active layer samples across the sites sampled. All fungal isolates were screened using enzymatic, pH and antifungal assays to identify their virulence potential. Aspergillus hiratsukae, A. thermomutatus and R. cf. mucilaginosa, known human opportunistic fungi, were identified, displayed phospholipase, esterase, proteinase and hemolytic activities. All three also displayed the ability to grow at 40 & DEG;, 45 & DEG; and/or 50 & DEG;C and resistance to fluconazole and itraconazole; additionally, R. cf. mucilaginosa showed resistance to amphotericin B and viability after 100 d at -80 & DEG;C. A. thermomutatus UFMGCB 17415 killed the entire larvae of Tenebrio molitor in six days and R. cf. mucilaginosa UFMGCB 17448 and 17473 in three and four days, respectively. The melting of maritime Antarctic permafrost as a result of climate change may threaten the release of wild strains of pathogenic fungi geographically isolated for long time, which may in turn be transported within and beyond Antarctica by different biological and non-biological vectors. (c) 2022 British Mycological Society. Published by Elsevier Ltd. All rights reserved.