Journal of Plant Diseases and Protection最新文献

Jambu plants (Acmella oleracea) exhibiting necrotic angular leaf spots were collected in Belém—Pará, Brazil. Suspected to be a disease caused by nematodes, the jambu leaves were processed and the presence of nematodes from Aphelenchoides genus was observed using a light microscope. These nematodes were reared on Fusarium sp. and subsequently morphologically and molecularly characterized to species level. Aphelenchoides sp. associated with jambu exhibited morphological and morphometric characteristics similar to those within the A. besseyi complex (A. besseyi sensu stricto, A. oryzae and A. pseudobesseyi). Still, these characteristics were insufficient to confirm the identity of this population. However, the Bayesian inference analysis, utilizing the expansion segment of the large subunit (D2-D3 LSU) of nuclear ribosomal DNA, yielded results with a high posterior probability, indicating that the Aphelenchoides sp. associated with jambu belongs to the A. pseudobesseyi species. Under controlled conditions, the reproduction of the nematode in the leaf tissues (RF > 1) was observed, resulting in disease symptoms. The highest reproductive rate of A. pseudobesseyi (RF = 2.6) was observed from inoculation with 100 nematodes per leaf (500 nematodes per plant). Based on Seinhorst analysis, the tolerance limit in jambu plants infected with A. pseudobesseyi was 250 nematodes. It is concluded that A. pseudobesseyi is the etiological agent of the jambu angular leaf spot. For future evaluation of jambu resistance on A. pseudobesseyi, an inoculate maximum of 100 nematodes per leaf is recommended.

The main objective of this study was to estimate and compare substitution matrixes of nucleotide frequencies for Tomato leaf curl New Delhi virus (ToLCNDV) with recently identified begomoviral isolates from two medicinal false daisy (Eclipta prostrata) and tomato (Solanum lycopersicum) plants. The ToLCNDV has become a significant limitation to vegetables production in many countries. A polymerase chain reaction was conducted to conserve the existence of begomoviral infection. The acquired amplicon was amplified using primers appropriate to the sequence in order to retrieve the full genome. The sequence analysis has confirmed the presence of ToLCNDV in symptomatic plants. The complete genome sequence having a 2.6–2.7 kb entire genome of ToLCNDV was obtained. An investigation of the phylogenetic and evolutionary history has verified the connection between this virus and other closely related viruses. The available nucleotide frequencies of codon regions (A, T/U, C, G) with newly isolates revealed 20–28% substitution matrixes. There was a minimal difference of nucleotide frequencies’ with already submitted database of this virus. Substitution matrixes, which quantify the probability of nucleotide substitutions evolving over a period of time, offer valuable information about mutation patterns and the forces driving evolution. This comparative analysis enhanced the comprehension of the genetic diversity of ToLCNDV and its possible consequences on medicinal plants. It also assisted in the formulation of efficient control measures and the preservation of begomoviruses in medicinal plant biodiversity. The information presented here is highly valuable for understanding the ToLCNDV biology and epidemiology, and it would also assist in disease management in the future.

Yam belongs to a very diverse plant genus (Dioscorea L.) that includes more than 600 species, both wild and cultivated. In Cuba, different species are distributed in the central and eastern regions, where the most widespread cultivars belong to the species water yam (Dioscorea alata L.) and white yam (Dioscorea cayenensis subsp. rotundata (Poir.) J. Miège). The major constraints faced by yam production areas are those caused by viral diseases. In this sense, potyviruses have the greatest economic impact, since they can cause losses of more than 50% in agricultural yields. The movement of propagules between plantations without phytosanitary certification has facilitated the spread of viruses throughout the production areas. Understanding the relationships between the host, virus, vector, and ecosystem is fundamental for successful disease management and for increasing agricultural yields. The objective of the present work was to determine the effect of using virus-free planting material and plantain barriers on the production of two yam cultivars. For this purpose, potyvirus-free certified and non-certified planting material were evaluated inside and outside a live barrier based on plantain ‘Burro CEMSA’. The virus incidence and production of these plants were determined in each of the experiments conducted. It was possible to reduce the field incidence of viral diseases (average infection decreased from 60 to 15%). The barrier also prevented yield losses of 50–57% for both cultivars, compared to the farmer’s usual practices.

The ascomycete Hymenoscyphus fraxineus causes the devastating ash dieback disease of European ash (Fraxinus excelsior L.). Spore traps are often used to measure the amount of ascospores in the environment, but the pathogen-load of the soil in ash stands has not been recorded so far. This is of particular interest with regard to the occurrence of ash stem necrosis, a decisive factor for the severe course of the disease. In order to gain a more differentiated insight into the pathogen-load in ash stands, we analysed soil samples from four ash tree sites in southern Germany, covering a clone plantation, two seed orchards and a forest. The pathogen-load was determined using a quantitative TaqMan real-time PCR assay for ten to twenty plots per stand. Results obtained by the species-specific assay highlighted that the pathogen-load is heterogeneously distributed in the ash stands. H. fraxineus DNA targets were detected in 17% of the soil samples. The pathogen-load differed according to soil depth, with the highest pathogen abundance in the top 5 cm, followed by 5–10 cm and finally 10–15 cm. Pathogen-load and thereby infection pressure were found to be highly variable for the individual trees in one stand. Overall, the study discovered detectable levels of H. fraxineus in the soil of all four study sites, which supports the hypothesis that H. fraxineus can be found in the soil of ash stands. The qPCR approach was found to be an effective method for monitoring the load of H. fraxineus in soil and for demonstrating the successful application of the method on the sample type of custom-made spore traps. Results suggest the implication of site-specific pathogen-load determination in future H. fraxineus-monitoring and selection of less susceptible ash trees for breeding and seed production.

Unintended sprouting of potato tubers (Solanum tuberosum) occurs within the professional production chain during transportation or storage due to the break of dormancy by changing environmental conditions. The sprouting of high-quality seed potatoes, for example, results in huge amounts of sprouts which complicate the planting process and are, therefore, manually removed and discarded. However, such sprouts can be very useful and sustainable when used as propagation material, helping to avoid losses of seed potatoes and increasing productivity per individual seed potato tuber.

In 1925, the American entomologist Walter Sidney Abbott proposed an equation for assessing efficacy, and it is still widely used today for analysing controlled experiments in crop protection and phytomedicine. Typically, this equation is applied to each experimental unit and the efficacy estimates thus obtained are then used in analysis of variance and least squares regression procedures. However, particularly regarding the common assumptions of homogeneity of variance and normality, this approach is often inaccurate. In this tutorial paper, we therefore revisit Abbott’s equation and outline an alternative route to analysis via generalized linear mixed models that can satisfactorily deal with these distributional issues. Nine examples from entomology, weed science and phytopathology, each with a different focus and methodological peculiarity, are used to illustrate the framework.

The apple crop, integral to global agriculture, is facing a significant challenge in the form of mosaic disease, reducing productivity, particularly in temperate regions of the world. The intricate biochemical and physiological responses of apple genotypes to mosaic infection induced by apple mosaic virus (ApMV)/apple necrotic mosaic virus (ApNMV) were investigated in this study. Higher phenolic contents, DPPH, flavonoids and flavanols were recorded from mosaic-infected apple genotypes in comparison with their respective counterparts. The impact on carbohydrates/total starch and chlorophyll content revealed a substantial reduction in mosaic-infected as compared to healthy leaves, which emerges as a quantitative biomarker for measuring infection severity and offering insights into the compromised photosynthetic ability of infected leaves. In mosaic-infected genotypes, PAL activity, malondialdehyde and antioxidant enzymes were greater, strengthening the powerful antioxidative defense mechanism against mosaic infection. Principal component analysis provided a comprehensive overview, identifying key biomarkers and elucidating the underlying biochemical processes linked with apple mosaic disease. This research provides significant insights for future apple breeding programs by providing a more detailed knowledge of the biochemical intricacies underpinning plant defense systems against mosaic infection in apples.

Maize (Zea mays L.) stalk and ear rots are the most serious diseases, affecting grain yield and quality in a number of regions of the world. The purpose of this study is to evaluate the efficacy of biochar and wood vinegar from guava trees (Psidium guajava L.) against Fusarium verticillioides, the pathogen that causes stalk and ear rot diseases, as well as the growth and anatomical traits of maize in laboratory and greenhouse experiments. In in vitro studies, biochar and wood vinegar at concentrations of 0.50, 1.00 and 2.00% (v/v) were tested on the mycelium growth of the pathogen. The results showed that wood vinegar had a high ability to inhibit the pathogen’s growth at a concentration of 2% (78.32%). Treating corn cobs with these treatments at concentrations of 2% led to a decrease in the severity of ear rot. Soil drenching with biochar and wood vinegar reduced the disease severity of stalk rot disease in maize in greenhouse experiments, with wood vinegar being the most effective in reducing the disease severity compared to the control. Biochar and wood vinegar both clearly affected plant growth, as measured by changes in plant height, fresh weight and dry weight of maize plants. Furthermore, these treatments enhanced the anatomical characteristics of maize roots and leaves compared to the untreated control plants. Data also revealed that total phenol contents and enzyme activity of peroxidase (POD) increased in treated plants with these treatments, but the highest increase was obtained when biochar was applied. These results highlight the efficacy of biochar and wood vinegar as effective, safe and eco-friendly methods to control of stalk and ear rot disease of maize and improve the anatomical characteristics and growth of plants.

Two-spotted spider mite (Tetranychus urticae Koch, 1836, Acari: Tetranychidae) causes significant yield losses in cultivated plants, especially depending on the season. Chemical methods are the main methods of controlling this pest. However, besides the environmental, human, and animal health problems arising from chemical control, adverse effects such as resistance and residues limit the success and sustainability of chemical control. This experiment was conducted in the applied acarology laboratory of the Directorate of Plant Protection Central Research Institute in Ankara, Türkiye, in incubators maintained at 25 ± 1 °C temperature, 50–65% humidity, and 16 L: 8 D h photoperiod. In this study, the potential acaricidal effect of aqueous extracts of Morus rubra, Daphne odora, Ficus carica, Matricaria chamomilla, and Mentha pulegium collected from Ankara and Adana provinces on T. urticae was investigated. For this purpose, the leaves of the plants were dried and ground and 1%, 3%, 6%, and 12% concentrations (w/v) of the extracts obtained were tested in three different application periods (1–6 day). Dipping and spraying methods were used to determine mortality and toxicity. The highest effect was 94.4% at the end of the 6th day at a 12% concentration of M. pulegium in the dipping method. On the other hand, the lowest mortality effect was 18.2% at the same time and concentration of M. chamomilla. In lethal toxicity studies, the highest toxicity was obtained from F. carica with an LC₅₀ value of 4756 mg L⁻¹, and the lowest toxicity was obtained from D. odora with an LC₅₀ value of 12,417 mg L⁻¹. We believe that plant extracts provide a valid alternative in effectively controlling two-spotted spider mites, reducing the need for pesticide use and minimizing residues.

Anthracnose caused by Colletotrichum is an increasingly severe disease of common vetch that reduces plant yield and quality. In this study, the effects of anthracnose on the rhizosphere soil microbial community of common vetch were studied via high-throughput sequencing. The relationship among the rhizosphere soil microbes and soil properties were analyzed. Lower fungal diversity was observed in rhizosphere soils of diseased plants. Variations in relative abundance were observed in the fungal phyla Mortierellomycota and Glomeromycota and in the bacterial phyla Acidobacteria, Oxyphotobacteria, and Verrucomicrobia. Gammaproteobacteria and Deltaproteobacteria were significantly more abundant in the rhizosphere soil of healthy plant. The bacterial community in the rhizosphere soil of diseased plant was involved in the synthesis of amino acids (glycine, serine, threonine, alanine, aspartate, and glutamate). Results of a redundancy analysis showed that Colletotrichum was negatively correlated with soil available potassium (AK) and the content of soil organic matter (SOC); however, it was positively correlated with soil pH. The relative abundances of Bacillus showed a negative correlation with soil pH and a positive correlation with AK and SOC content. The present study demonstrated that anthracnose could affect the rhizosphere soil microbial communities in common vetch, and soil properties have a close relationship with the rhizosphere soil microbes of common vetch.