Journal of Plant Diseases and Protection最新文献

Aphids hide under leaves, reproduce rapidly, and require early detection to prevent crop damage, disease transmission, and ensure effective pest management. This study presents a novel approach for aphid detection by utilizing hyperspectral imaging, multivariate classification methods and spectral information divergence (SID) analyses. The hyperspectral images average spectrum (n = 336) showed significant differences between healthy and infested leaves. Time-series classification was performed over 14 days after infestation using four distinct machine learning algorithms. Early-stage infection detection may not relate to internal physiological alterations within the leaf but rather to the physical presence of the aphid behind the leaf, obstructing subtle physiological signatures. Implementation of spectral endmembers in the VIS-NIR reference spectrum led to the identification of an informative abundance SID map within the 710-825 nm range, useful for further classification. Machine learning classification resulted in support vector machines achieving 99.20 accuracy. Using random forest, twenty-two most important variables found effective in boosting classifier performance. The selected model also extended to real-world scenarios by testing progressing infestation patterns over 14 days on independent data sets, confirming the system's reliability. Signal normal variant pre-treatment with partial least squares regression was effective in the estimation of aphid populations, achieving a 0.81 coefficient of determination (R ²) and a 10.29 root-mean-square error of prediction for test datasets. In conclusion, the proposed method was able to successfully detect aphid colony infestation, both earlier and in locations that are invisible during standard human inspection.

Phthorimaea absoluta is an invasive pest that causes substantial damage to Solanaceous crops, such as tomato and potato. This study evaluated the resistance of five commonly cultivated potato varieties to P. absoluta infestation in field conditions across South Africa. Morphological parameters, gas exchange, and nutrient assimilation parameters were analysed in both infested and uninfested plants. Valor exhibited the highest tolerance, showing minimal leaf damage, fewer mines, optimal gas exchange, and greater assimilation of key nutrients (e.g. iron, zinc, and manganese), which may enhance its defensive capacity against pests. Conversely, Sifra was identified as the most susceptible cultivar, with reduced nutrient uptake and significant physiological disruption in response to infestation. Infested plants showed a decrease in photosynthesis, transpiration, and stomatal conductance, along with an increase in intercellular CO₂, highlighting the harmful effects of P. absoluta. These findings support the selection of cultivars in breeding and integrated pest management programmes, especially in African contexts where field data are limited.

European ash populations face a significant threat from the invasive fungus Hymenoscyphus fraxineus, leading to ash dieback disease. The absence of resistant individuals and restrictions on biotechnological solutions hinder the ability to combat this widespread illness in the near term. Priming strategies offer an alternative approach to boost stress tolerance not only in this scenario but also in other endangered tree species by triggering plant defense mechanisms. The non-proteinogenic amino acid β-aminobutyric acid (BABA) has demonstrated potential in enhancing resistance to diverse stressors in plants. Despite limited research on forest tree species, the current study evaluated BABA’s effectiveness in mitigating ash dieback disease severity and explored potential correlations between priming treatments and epigenetic modifications. The results indicated that BABA enhanced stress tolerance in ash seedlings following inoculation with Hymenoscyphus fraxineus. BABA effectively decreased the development of necrosis associated with ash dieback disease in seedlings five months post-inoculation. Additionally, treatments involving BABA were linked to observed epigenetic alterations. Elevated levels of the non-canonical deoxynucleosides 5-(hydroxymethyl)-2'-deoxycytidine (5-hmdC) and 5-(hydroxymethyl)-2'-deoxyuridine (5-hmdU) were confirmed subsequent to the treatments. This study highlights the potential of BABA and other priming strategies in enhancing disease tolerance in forest tree species like European ash. Short-term improved stress tolerance and epigenetic changes were confirmed. Yet, the exact priming conditions for inducing long-term effects in plants, including long-living forest trees, remain unknown, posing a challenge for applying priming strategies to manage ash dieback and protect many other endangered tree species.

Eggs represent a crucial life stage for Meloidogyne incognita, and viable eggs are frequently employed in nematode research. The common issue currently encountered with established technologies is that higher concentrations of sodium hypochlorite (NaOCl) result in irreversible damage to M. incognita eggs. Therefore, developing a novel method to avoid such a problem is highly important. In this study, the fresh roots of infected cucumber plants were prestored in plastic bags at 28 °C, after which M. incognita egg masses were collected from these root samples. Egg masses from roots prestored for more than 48 h could be efficiently disassociated with a low concentration (0.3%) of NaOCl in a short period of time (2 min), representing an innovative new method. Moreover, the hatchability of the harvested M. incognita eggs was maximized in this work. Additionally, if the treatment time was extended beyond 5 min, 0.3% NaOCl affected larval hatching irreversibly. Overall, these findings indicate that prestorage of infected roots in plastic bags enables the application of lower concentrations of NaOCl in M. incognita egg extraction.

The six-spotted zigzag ladybird beetle, Cheilomenes sexmaculata (Coleoptera: Coccinellidae), is a prevalent generalist predator in India, commonly observed on maize and wheat during the summer and winter seasons. Ladybird beetles are important natural predators of aphids and other sap-sucking pests in maize and wheat crop ecosystems. Enhancing their abundance in the field through attractants is essential for the success of augmentative biological pest control programmes. This study aimed to evaluate the effectiveness of eight synthetic volatiles in attracting ladybird beetles using electroantennogram tests, olfactometer bioassays, and semi-field and field trials. In EAG studies, benzaldehyde and terpineol significantly triggered responses in adult males and females without any significant difference between the sexes. In dose-dependent olfactometer bioassays, at five doses (10 μg, 100 μg, 300 μg, 700 μg, and 1000 μg), C. sexmaculata adults exhibited a preference for 700 μg of benzaldehyde (74.28%) and terpineol (72.62%) over other doses. However, none of the twelve blends of these two attractive compounds showed a significant attraction to C. sexmaculata. Subsequently, all these eight synthetic semiochemicals were evaluated for ladybird beetle attraction in semi-field and field trials over different weeks. Terpineol (50.20 ± 0.31), benzaldehyde (41.67 ± 0.35), and (+)-3-carene (27.73 ± 0.33) were confirmed as attractants in semi-field trials over 3 weeks, and the same trend was noticed in the field trials over the 8 weeks. However, the attraction patterns in the field trails varied slightly between grubs and adults regarding (+)-3-carene and methyl salicylate. While adults clearly preferred (+)-3-carene over methyl salicylate, grubs showed no significant difference in attraction to these two compounds. This study lays the groundwork for developing optimal attractant formulations for C. sexmaculata, potentially enhancing the biocontrol services of this predator in its native area, such as India.

Transforming agriculture into a sustainable system includes innovative, safe, and sustainable management of virus diseases. Advances in cutting-edge biotechnological tools, such as CRISPR/Cas9 genome editing (clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9), environmental RNA interference (RNAi), and the application of natural antiviral compounds, present promising new strategies for effective virus control. Highly sensitive and validated diagnostic tools allow early detection and targeted management strategies. The 56th meeting of the Deutsche Phytomedizinische Gesellschaft (DPG) working group on "Viruskrankheiten der Pflanzen" tackled the latest developments and challenges in the field of plant virology in Germany, covering topics on genomic technologies, diagnostics and quarantine regulations, virus–host interaction, virus diversity, plant immunity, and more. A special emphasis lay on the applied side of plant virology, as here, pressing agricultural challenges have to be met. In this perspectives paper, we give a summary on the conference’s findings and highlight possibilities to derive novel strategies for disease control.

Common ash, Fraxinus excelsior, is threatened by the invasive pathogen Hymenoscyphus fraxineus, which causes ash dieback. The pathogen is rapidly spreading throughout Europe with severe ecological and economic consequences. Multiple studies have presented evidence for the existence of a small fraction of genotypes with low susceptibility. Such genotypes can be targets for natural and artificial selection to conserve F. excelsior and associated ecosystems. To resolve the genetic architecture of variation in susceptibility it is necessary to analyze segregating populations. Here we employed about 1000 individuals of each of four single-tree progenies from potentially tolerant mother trees to identify full-sibling (full-sib) families. To this end, we first genotyped all 4000 individuals and the four mothers with eight SSR markers. We then used the program COLONY to predict full-sibs without knowledge of the paternal genotypes. For each single-tree progeny, COLONY predicted dozens of full-sib families, ranging from 3–166 individuals. In the next step, 910 individuals assigned to full-sib families with more than 28 individuals were subjected to high-resolution genotyping using over one million genome-wide SNPs which were identified with Illumina low-coverage resequencing. Using these SNP genotyping data in principal component analyses we were able to assign individuals to full-sib families with high confidence. Together the analyses revealed five large families with 73–212 individuals. These can be used to generate genetic linkage maps and to perform quantitative trait locus analyses for ash dieback susceptibility. The elucidation of the genetic basis of natural variation in ash may support breeding and conservation efforts and may contribute to more robust forest ecosystems.

India, renowned for its rich agricultural heritage, is ranked among the three world crop suppliers. Farmers face numerous challenges, including difficulty in selecting profitable crops suited to their soil and unpredictable weather conditions that affect yield predictions. To address these issues, various analytical methods have been employed in agricultural yield-prediction studies. Plant diseases are prevalent in agriculture, prompting the need for effective detection methods. Therefore, in this study, the proposed agro insights’ model aimed at assisting farmers in predicting or deciding the type of soil and crop to sow, which is implemented through ML and DL methods to predict the optimal crop to be cultivated by deciding diverse input variables such as the region, soil, and crop type. The accuracy of soil classification and crop recommendation is 93.3% using random forest technique and crop disease detection is 96% using CNN technique.

Aphids and mites, which cause severe yield reductions, are commonly controlled by commercial insecticides, which has led to serious environmental problems. Research is currently being performed on developing safe and low-toxicity botanical pesticides, which are an effective way to reduce environmental pollution and pesticide residue in food. Trifolium pratense L. is a globally important forage and vulnerable to aphids and mites. The differences in secondary metabolites between infested leaves (ILs) and pest-free leaves (PFLs) of T. pratense were investigated by gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography (HPLC) to determine the chemical defense mechanism. The results revealed significant differences in the contents of fatty acids and isoflavones. The contents of neophytadiene, methyl linoleate, daidzein, genistein, formononetin, and biochanin A in ILs were significantly increased compared with PFLs. The insecticidal compounds were further separated by bioassay-directed fractionation against Myzus persicae Sulzer, Brevicoryne brassicae Linnaeus and Tetranychus cinnabarinus Boisduval. The ethyl acetate (EtOAc) extract had greater insecticidal activity than the petroleum ether (PE) extract. Notably, there was no significant difference between the EtOAc extract and avermectin at 1.00 mg/mL against T. cinnabarinus after 48 h. The following ten compounds were obtained from the PE and EtOAc extracts: prunetin (1), genistein (2), formononetin (3), biochanin A (4), 8-hydroxy-4',7-dimethoxyisoflavane (5), L-maackiain (6), 4-hydroxy-3-methoxy-(6aR,11aR)-8,9-methylenedioxypterocarpan (7), β-sitosterol (8), linoleic acid (9) and linoleic acid monoglyceride (10). Compound 7 exhibited the highest level of insecticidal activity, which was close to that of avermectin. The results indicated that isoflavones were the main active insecticidal components.

The lesion nematode Pratylenchus brachyurus is a major pest of soybean in Brazil, managed by treating seed with nematicides and replacing corn for pearl millet (Pennisetum glaucum) and rattlepods (Crotalaria spp.) as a second crop. However, these cover crops are not profitable, leading growers to consider alternatives as cowpea, sunflower, and sorghum. In fact, although cowpea and sorghum are susceptible to P. brachyurus, cowpea is widely cultivated in the Brazilian Cerrado, where P. brachyurus is prevalent, and the forage sorghum ‘BRS Ponta Negra’ has been recommended for P. brachyurus management, based on field observations. Considering the increasing importance of cowpea in the Brazilian Cerrado, three pot trials were carried out to evaluate the host status of modern cowpea cultivars for P. brachyurus. Additionally, two pot trials were carried out to evaluate the effect of cowpea, sunflower, forage sorghum ‘BRS Ponta Negra’, pearl millet and showy rattlepod on soybean production in soil with P. brachyurus, taking account the scarcity of studies that prove the benefits of replacing corn for resistant crops on soybean grain production. The five cowpea cultivars tested were highly suitable hosts for P. brachyurus, supporting previous findings. Therefore, cowpea should be avoided in infested growing areas, especially as a second crop after soybean. Among the cover crops, only showy rattlepod consistently decreased P. brachyurus population density and increased soybean grain production, proving to be more effective than pearl millet in managing P. brachyurus.