Fungicide Application Research Articles

Earthworms-enhanced bacterial degradation of the chiral fungicide penflufen R-enantiomer

The widespread application of chiral fungicides as seed-coating agents in agriculture has led to serious residue accumulation in soil, increasingly drawing attention to soil pollution remediation strategies for chiral pesticides. This study explored the role of earthworms and soil microorganisms in selectively accelerating the degradation of penflufen in soil. The results showed that soil microorganisms significantly accelerated penflufen enantiomer degradation, particularly the R-enantiomer. Nocardioides, Variovorax, Arthrobacter, and Pseudomonas were identified as key degrading microorganisms associated with the preferential degradation of the R-enantiomer. The addition of earthworms further significantly enhanced the preferential degradation of the R-enantiomer. Importantly, earthworms markedly promoted the growth and reproduction of the four aforementioned degrading microorganisms in soil treated with enantiomers. Notably, the relative abundance of these degrading microorganisms was significantly higher in R-enantiomer-treated soil with earthworms than in soil treated with the S-enantiomer. Additionally, earthworms significantly increased the relative abundance of degradation genes p450, bphA1, and benA in the soil, especially in the R-enantiomer treated soil. Nocardioides, Variovorax, Arthrobacter, and Pseudomonas were identified as potential hosts for the degradation gene benA. More importantly, twelve strains of penflufen-degrading bacteria were isolated from the treated soil, of which eight belonged to the aforementioned four microorganisms and exhibited a remarkable ability to preferentially degrade the R-enantiomer. This finding highlights the potential of adding earthworms to soil, in conjunction with key degrading microorganisms, which preferentially accelerates penflufen R-enantiomer degradation.

Aerial dispersal of Venturia inaequalis ascospores with under-canopy sprinkler irrigation for apple scab management

AbstractSprinkler irrigation systems can release ascospores of Venturia inaequalis, the cause of apple scab, from infected leaves on the ground under conditions unsuitable for infection, and thus reducing the primary inoculum. Under-canopy irrigation was carried out for two hours in the middle of the day over overwintered apple leaves heavily infected with scab, either in a wind-protected enclosure or in a wind-exposed orchard. Ascospores were captured with rotating-arm spore traps at heights ranging from 0.3 m to 3.0 m above the ground. Ascospores dispersed above the irrigated layer and were detected at all heights above the sprinklers. Wind played a critical role in spore transport, evident from the set-up where wind interference was minimised by a wind fence, resulting in higher airborne spore numbers across all measured heights compared with the orchard exposed to unrestricted wind conditions. Furthermore, vertical temperature gradients significantly correlated with spore distributions, particularly where negative gradients at heights between 0.3 m and 0.05 m and positive gradients at heights between 1.0 m and 0.3 m led to spore retention within the irrigated zone. The findings highlight that ascospores, dispersed above the irrigated layers, could settle on susceptible tissues. It thus becomes imperative to ensure a rain-free period of at least 24 h post-irrigation and, if a rainfall shortly occurs after irrigation, the application of curative fungicides becomes essential following unexpected rain. Reliable weather forecasts are therefore crucial in determining the effectiveness of under-canopy irrigation to reduce apple scab incidence.

In vitro evaluation of fungicides against eucalyptus stem canker pathogens in Ethiopia

Field surveys of Eucalyptus camaldulensis diseases were conducted during 2019-20 and 2020-21 in Ethiopia. This species was the most commonly planted in the surveyed fields and exhibited stem canker diseases. Sampling was performed from diseased stems and branches displaying clear symptoms. Morphological and PCR assays of the ITS1 and ITS2 loci were conducted to identify the fungal pathogens. Lasiodiplodia theobromae and Didymella pinodella were identified as the fungal pathogens causing E. camaldulensis stem canker diseases. Four nationally licensed fungicides viz. Vitra (copper hydroxide), Ridomil Gold (metalaxyl-M + mancozeb), Liveshow (pyraclostrobin + epoxiconazole), and Sabozeb (mancozeb) were evaluated for their in vitro control efficacy against the identified fungi at different concentrations (500, 1000, 1500, and 2000 ppm). Vitra and Liveshow were found to be the most effective fungicides at 2000 ppm for the control and treatment of E. camaldulensis stem canker diseases. The identification of L. theobromae and D. pinodella as causal agents of E. camaldulensis is crucial for targeted disease management strategies. The evaluation of four fungicides at different concentrations provided valuable information for selecting the most effective treatment options for practical management practices of the diseases. This research serves as the first report on the management of Eucalyptus disease in Ethiopia, laying the foundation for future studies and contributing to the development of sustainable disease management practices. The findings of this research can guide policymakers, researchers, and agricultural practitioners in implementing targeted fungicide applications to mitigate the impact of stem canker on Eucalyptus plantations and improve their productivity.

Influence of fungicide on soybean seed quality from delayed harvest and environment

AbstractField studies in 2019–2020 evaluated the influence of fungicide application on seed quality from delayed harvest (approx. 20, 30, and 44 days after optimum harvest timing, i.e., 13% seed moisture). Treatments included nofungicide, pydiflumetofen plus difenoconazole (13.7 fl oz/acre Miravis Top, Syngenta), or mefentrifluconazole plus pyraclostrobin plus fluxapyroxad (8 fl oz/acre Revytek, BASF). Effect of environment was investigated in both field (natural rainfall events) and environmentally controlled growth chambers (79°F or 90°F with 30% or 100% relative humidity and exposed for 48 or 96 h) for potential impacts on soybean [Glycine max (L.) Merr.] seed quality. Seed quality was based on a rating scale of 1 to 10 with 1 being seeds in good condition and 10 being seeds in poor condition, based on USDA reference images. Fungicide application had no effect on seed quality from delayed harvest or a saturated environment (100% relative humidity). Delaying harvest beyond approximately 20 days past optimum timing can result in reduced seed quality regardless of fungicide application (1.0 to 2.0 vs 4.0 to 8.1 rating). In addition, seedpod exposure averaged across temperature and relative humidity environments for as little as 96 h after optimum harvest timing can result in deteriorating seed quality issues (3.2 vs 1.4 rating) regardless of fungicide application. Results indicate that soybean harvest delayed 20 days after optimum timing and subjected to seasonal rainfall events or seedpods exposed to completely saturated conditions for 96 h associated with a tropical weather event will result in soybean seed quality deterioration regardless of fungicide application.

Co-Occurrence of Fusarium and Alternaria Metabolites in Brewing Barley Monitored during Two Consecutive Years (2019-2020).

Known mycotoxins have been investigated for years. They have been included in legislation and are meticulously controlled in most cereals, cereal-related products, and raw materials of animal origin. However, there are still mycotoxins that need to be addressed by regulations and subsequently are not monitored but can still occur in relatively high concentrations. This research aimed to assess the occurrence of common Fusarium mycotoxins in hulled barley. Samples of hulled barley were treated in the field with two protective treatments, alongside a control sample sans treatment. Furthermore, we aimed to assess the occurrence of Alternaria mycotoxins in the chosen samples. The results have shown that Fusarium mycotoxins were mostly determined by climatic conditions (no mycotoxins in 2020, except siccanol). Most interesting was the appearance of infectopyron, an Alternaria toxin that was detected in all samples in 2019 and in the majority of samples in 2020. The highest concentration was detected in 2019 in hulled barley with 536 µg/kg, while in 2020, the highest concentration of this mycotoxin reached 350 µg/kg. These findings depict the need for further research on food safety regarding mycotoxins, and the need for additional changes in legislation. This investigation shows that fungicide application in rainy years cannot efficiently suppress mycotoxin production. Additionally, even in dry years, some of the mycotoxins not involved in legislation, such as infectopyron and siccanol, do not respond to the application of fungicides.

PSVIII-8 The impact of foliar fungicide application on barley silage fermentation characteristics and performance of lactating dairy cows

Abstract Forages are an important component in dairy cow diets and barley silage is the primary forage source in western Canada and parts of the USA. Foliar fungal diseases can infect barley, thereby causing leaf damage and a loss of yield and quality. The objectives were to determine the effects of foliar fungicide application on two barley forage varieties, one resistant (CDC Fraser) and the other susceptible (Claymore) to foliar fungal disease, on silage ensiling characteristics and feed intake, milk production and composition, ruminal pH, and nitrogen (N) balance in dairy cows. Multiparous Holstein cows [n = 12; mean (ays in milk (DIM) = 40 ± 17; mean body weight (BW) = 720 ± 26 kg] at the start of the experiment) were used in a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of dietary treatments. Experimental periods were 25 d, with 18 d of dietary adaptation and 7 d of sample and data collection. Test diets were: 1) fungicide-treated Claymore silage (CF); 2) untreated Claymore silage (CNF); 3) fungicide-treated CDC Fraser silage (FF); and 4) untreated CDC Fraser silage (FNF) as the major source of forage. Forage yields were 1.86 (FNF), 1.46 (CNF), 1.17 (FF), and 1.35 (CF) t dry matter (DM)/ha, likely reflective of the low rainfall during the growing season. Experimental silages were similar in crude protein (mean = 14.0%; DM basis), ammonia (mean = 1.95%), and total volatile fatty acid (mean = 9.25%) concentrations. CDC Fraser silage had greater lactic acid concentration (P < 0.001) but decreased pH (P = 0.01) and acetic acid concentration (P < 0.01) than Claymore silage. Silage aNDF contents (DM %) were similar in FF and FNF, but greater in CNF than CF (interaction; P < 0.05). Without fungicide application, barley variety had no effect on silage starch content (DM %), whereas with fungicide application, Claymore had a greater silage starch content than CDC Fraser (interaction; P < 0.05). Dry matter intake, milk yield, and milk composition were unaffected by diet (P > 0.05). Total tract nutrient digestibility was unaffected by diet (P > 0.05). Intake of N, and urinary and fecal N excretion, total N excretion, milk N, and apparent N balance (expressed as g/d or % of N intake) were unaffected by diet (P > 0.05). Ruminal short-chain fatty acid (SCFA) concentrations and pH were unaffected by diet (P > 0.05); however, total SCFA concentration was similar in CF and CNF but was greater in FNF than FF (interaction; P < 0.05). Valerate concentration was similar in FF and FNF but greater in CF than CNF (interaction; P < 0.05). Foliar fungicide application on barley, regardless of variety susceptibility to fungal diseases, did not negatively affect silage quality or dairy cow performance.

Organic fungicides and diphenylamine shift microbiomes of ‘Fuji’ apples during storage

The native microbiome plays an important role in biocontrol efficacy, but less is known about how the microbiome responds to conventional and organic natural product fungicides. This study investigated the effects of the conventional fungicide fludioxonil and the organic fungicide natamycin, with and without the superficial scald inhibitor diphenylamine (DPA) on the microbiomes of ‘Fuji’ apples from 1 to 28 d of storage at 0.5 °C plus 7 d at 20 °C. We hypothesized that fungicide applications would shift the microbiome, with a more pronounced effect from natamycin due to the target specificity of fludioxonil. We also predicted that the antioxidant properties of DPA would shift both bacterial and fungal microbiomes. We found that natamycin resulted in modest fungal shifts and fludioxonil resulted in no observed shifts, while DPA strongly affected the fungal microbiome over time. Chemical treatment was not a predictor of bacterial microbiome variation, but bacterial communities shifted throughout storage. However, many of the trends that occurred during storage were reversed during the 7-d shelf life period at 20 °C after storage. Time in cold storage decreased the relative abundance of Pseudomonas, while DPA application reduced the relative abundance of Aureobasidium, both notable biocontrol genera. These results highlight how chemical applications such as DPA may have unintended effects on beneficial microbes that protect fruit from pathogen infection.

Effect of nozzles on disease control with spraying fungicides in soybean crops

ABSTRACT The productivity of the soybean crop (Glycine max) can be limited by several factors, including diseases. In the integrated management of diseases, one of the strategies used is chemical control. The aim of this experiment was to evaluate the influence of spray nozzle types on the chemical control of fungal diseases in soybean plants. The experimental design was randomised blocks, with six treatments and four replications. The treatments consisted of control (without fungicide application on soybean plants) and application of fungicides with different spray nozzles: hollow cone jet, double flat jet, extended range flat jet, wide angle flat jet and air induction flat jet. The sprayer used was the backpack pressurised by carbon dioxide CO2. The experiment was installed in the Campos Gerais region (Paraná, Brazil); during three cropping seasons. The evaluated variables were incidence and severity, spray quality (covered area, droplet density, and relative amplitude) and yield components. It was concluded that the chemical control of fungal diseases in soybean plants reduced the proliferation of pathogens and losses in crop yield. There were significant changes in spraying quality in all analysed variables. There were no differences among the spray nozzle types regarding the analysis of incidence, severity and soybean yield components.

Selecting Bacillus strains antagonist to Erysiphe necator (Schw.) Burr. the causal agent of grape powdery mildew

ABSTRACT Grape powdery mildew (GPM) control is based on the preventive use of sulfur and curative application of synthetic fungicides, increasing the risk for producers’ health and environmental and fruit contamination. This work aimed to select Bacillus strains isolated from the Brazilian tropical semi-arid region that are effective antagonists to GPM. In an initial screening performed by spraying bacterial suspensions in detached grape leaves, six strains of Bacillus spp. showed disease symptom reduction higher than 70.0%. Two greenhouse experiments showed that the bacterial strains LCB03, LCB28, and LCB30 showed control efficiency >80%, statistically similar to a commercial formulation with Bacillus amyloliquefaciens QST713. 16s rDNA sequencing showed that strain LCB03 showed 100.0% homology to B. velezensis, while LCB28 has high homology to B. tequillensis (99.93%), and LCB30 had 99.71% homology with B. siamensis. As an average for both greenhouse experiments, weekly application of Bacillus sp LCB03, Bacillus sp LCB28, and Bacillus sp. LCB30 reduced the average incidence by around 50% and more than 80% for GPM severity.

Negative plant–soil feedback influences a dominant seeded species, Western yarrow (Achillea millefolium), in grassland restoration

Plant community ecology guides restoration of degraded lands, yet seed‐based restorations sometimes fail or result in unpredictable outcomes, necessitating a better understanding of community trajectory and stability. Western yarrow (Achillea millefolium) declined suddenly in two separate restoration projects after initial high relative abundance. To assess the potential role of soil pathogens, we surveyed plant and soil fungal communities in these restorations, and used an 8‐year‐old field experiment that crossed yarrow planted in varying densities with a fungicide treatment. Two greenhouse experiments then evaluated whether the suppressive effect in yarrow soil spread to native species used in restoration. Lower yarrow cover in a restoration project 5 years compared to 3 years after seeding coincided with higher relative abundance of fungal taxa that can cause disease, particularly Crown‐rot fungi (Paraphoma spp.). Paraphoma increased over time in experimental plots and coincided with yarrow decline. Decline onset was density‐dependent, occurring faster in plant communities where yarrow density was higher. Fungicide applications altered fungal pathogen communities and promoted yarrow cover relative to control plots. In the greenhouse, yarrow grew larger with fungicide, consistent with suppression of fungal pathogens. However, biomass of natives grown in yarrow‐conditioned soil was not affected by fungicides, suggesting pathogens did not spread. The rapid establishment and competitive nature of yarrow, followed by pathogen‐induced decline, make it an attractive early transitional “bridge species,” so long as its pathogens are species‐specific. Our results suggest negative plant‐soil feedback can drive rapid decline of individual species, and considering plant–soil feedback could improve restoration predictability.

Brown patch on tall fescue as influenced by nitrogen and fungicide applications

AbstractTall fescue (Festuca arundinacea Schreb.) is a cool‐season turfgrass species commonly used in the transition zone. Brown patch (Rhizoctonia solani Kuhn) can have a significant impact on quality of tall fescue between late spring and late summer and is impacted by management strategies including fertilization and fungicide use. The objective of this study was to evaluate the influence of four nitrogen (N) sources and two application rates (0, 74 kg ha−1 [low], or 220 kg ha−1 [high] annually) along with fungicide application (azoxystrobin applied or not applied) on tall fescue brown patch infection. Highest quality occurred when tall fescue received the highest level of N and fungicide treatment. If high levels of N were applied and no fungicide was used, quality was reduced significantly when brown patch was observed in tall fescue. For example, on July 21, 2023, when most intense brown patch occurred, tall fescue had variable brown patch levels: low N levels 2%–23% and high N levels 48%–66%. Across three rating dates in summer 2023, tall fescue receiving the low N level exhibited statistically similar brown patch among all N sources. Conversely, brown patch treated with high levels of N had lower brown patch in urea compared to humic‐coated urea and slow‐release N on at least one of the three dates. Applying N at a level of 220 kg ha−1 annually or higher can result in significant brown patch in some summers; lower N levels will reduce brown patch. Desiring high tall fescue quality requires the high N level and inclusion of preventive fungicide applications.

Enhancing Resistance to Cercospora Leaf Spot in Mung Bean (Vigna radiata L.) through Bradyrhizobium sp. DOA9 Priming: Molecular Insights and Bio-Priming Potential.

Mung bean (Vigna radiata L.), a vital legume in Asia with significant nutritional benefits, is highly susceptible to Cercospora leaf spot (CLS) caused by Cercospora canescens, leading to significant yield losses. As an alternative to chemical fungicides, bio-priming with rhizobacteria can enhance plant resistance. This study explores the potential of Bradyrhizobium sp. strain DOA9 to augment resistance in mung bean against CLS via root priming. The results reveal that short (3 days) and double (17 and 3 days) priming with DOA9 before fungal infection considerably reduces lesion size on infected leaves by activating defense-related genes, including Pti1, Pti6, EDS1, NDR1, PR-1, PR-2, Prx, and CHS, or by suppressing the inhibition of PR-5 and enhancing peroxidase (POD) activity in leaves. Interestingly, the Type 3 secretion system (T3SS) of DOA9 may play a role in establishing resistance in V. radiata CN72. These findings suggest that DOA9 primes V. radiata CN72's defense mechanisms, offering an effective bio-priming strategy to alleviate CLS. Hence, our insights propose the potential use of DOA9 as a bio-priming agent to manage CLS in V. radiata CN72, providing a sustainable alternative to chemical fungicide applications.

Limited role of fungal diversity in maintaining soil processes in grassland soil under concurrent fungicide stress

BackgroundFungicides are an effective tool for protecting crops and maintaining a steady food supply. However, as pathogens continue to evolve, it is crucial to prolong the effectiveness of fungicides by delaying resistance development. A key strategy to achieving this is to combine or rotate fungicides with different modes of action. As fungicides lack specificity, they inevitably affect both pathogenic and non-pathogenic fungi when surrounding environments are unintentionally contaminated. Our study aims to investigate the effects of recommended application methods to prevent resistance development, specifically repeated-single fungicide, simultaneous mixture, and sequential applications on non-target soil fungi, and the subsequent impacts on important soil processes. We used fungicides with different modes of action on soil microcosms inoculated with fungi at varying levels of diversity (3, 5, and 8 species) isolated from a protected grassland.ResultsWe found that repeated treatments of individual isopyrazam and prothioconazole differentially inhibited fungal activity. Although mixture applications are considered more protectant against crop pathogen resistance than repeated application, our study revealed stronger negative effects of simultaneous application on saprobic fungi and consequently on soil processes. However, contrary to expectations, higher fungal diversity did not translate to improved soil function under these conditions.ConclusionsThe simultaneous application of fungicides with different modes of action (MoA) has more pronounced non-target effects on soil compared to the individual or sequential application of fungicides. These non-target effects extend beyond the intended control of pathogenic fungi, impacting saprobic and beneficial soil microbes and the critical processes they drive. When fungicides are applied concurrently, microbial activities in the soil are significantly altered, even in soils with high microbial diversity. Our study emphasizes the importance of carefully considering the unintended consequences of fungicide use in agriculture. As we strive for a secure food supply, it is crucial to investigate the broader environmental impacts of these chemical interventions, including their effects on non-pathogenic fungi and overall soil health.

Transcriptomic and functional analyses on a Botrytis cinerea multidrug-resistant (MDR) strain provides new insights into the potential molecular mechanisms of MDR and fitness.

Botrytis cinerea is a notorious pathogen causing pre- and post-harvest spoilage in many economically important crops. Excessive application of site-specific fungicides to control the pathogen has led to the selection of strains possessing target site alterations associated with resistance to these fungicides and/or strains overexpressing efflux transporters associated with multidrug resistance (MDR). MDR in B. cinerea has been correlated with the overexpression of atrB and mfsM2, encoding an ATP-binding cassette (ABC) and a major facilitator superfamily (MFS) transporter, respectively. However, it remains unknown whether other transporters may also contribute to the MDR phenotype. In the current study, the transcriptome of a B. cinerea multidrug-resistant (MDR) field strain was analysed upon exposure to the fungicide fludioxonil, and compared to the B05.10 reference strain. The transcriptome of this field strain displayed significant differences as compared to B05.10, including genes involved in sugar membrane transport, toxin production and virulence. Among the induced genes in the field strain, even before exposure to fludioxonil, were several putatively encoding ABC and MFS transmembrane transporters. Overexpression of a highly induced MFS transporter gene in the B05.10 strain led to an increased tolerance to the fungicides fluopyram and boscalid, indicating an involvement in efflux transport of these compounds. Overall, the data from this study give insights towards better understanding the molecular mechanisms involved in MDR and fitness cost, contributing to the development of more efficient control strategies against this pathogen.

Natural Occurrence, Morpho‐Molecular Characteristics, and Pathogenicity of Fusarium spp. Associated With Chrysanthemum Wilt in Vietnam

ABSTRACTChrysanthemum Fusarium wilt (CFW) is a devastating soil‐borne disease affecting the cut chrysanthemum industry globally. In Vietnam, this disease has been occurring silently and is posing a risk of epidemic outbreaks in the southern provinces, especially Lam Dong. Results from a survey in 2023 showed that stunted growth, curved and small stems, dried‐rot roots, leaf drooping and green or yellow wilting of plants after transplanting or at their flower bud initiation were common symptoms observed across the main chrysanthemum‐growing farms in Lam Dong. The occurrence of CFW was recorded in relation with the host cultivar, irrigation method and fungicide‐spraying regime. Among the cultivars grown in Lam Dong, ‘Doa cu’ was the most susceptible to CFW. The use of sprinkler irrigation and infrequent application of fungicides were attributed to increase both disease incidence and severity. Thirty fungal isolates obtained from diseased plants were identified as Fusarium oxysporum and F. falciforme based on morphological features and molecular analysis of ITS and TEF‐1α genes. The detection frequency of these two species was almost equal, which shows their balanced role in the occurrence of CFW in Lam Dong. In‐planta pathogenicity assays of Fusarium isolates against plantlets grown from cuttings and invitro propagation showed a variation in pathogenicity and a specialisation of isolates for these planting materials. These results suggest that the profiles of population and aggressiveness of Fusarium isolates diverged with the type of planting material, and between the stock and the commercial farms.

Influence of weather parameters on rice blast disease progression in Tamil Nadu, India

Rice cultivation in Madurai district, Tamil Nadu, spans distinct cropping seasons: Kar (May – Jun), Semi-dry (Jul – Aug), Samba/ Late Samba (Aug – Sep), and Navarai (Dec – Jan), each with unique weather conditions and rice varieties. This study explores the correlation between weather parameters temperature, rainfall, humidity, sunshine hours, and wind speed and rice blast disease severity from 2021 to 2023. Using multiple linear regression with ordinary least squares (OLS), the analysis achieves high predictive accuracy (R² = 0.98). Results show that the maximum temperatures correlated negatively with disease severity (r = -0.869 to -0.892), while rainfall (r = 0.768 to 0.804) and wind speed (r = 0.766 to 0.938) correlated positively during the semi-dry season. Relative humidity exhibits varying impacts across seasons. These findings underscore the importance of tailored disease management strategies, such as targeted fungicidal applications during warmer seasons and optimized water management in others. By elucidating these dynamics, the study enhances understanding of weather-disease interactions, providing actionable insights to optimize disease management and enhance crop resilience in Madurai district.

Biological control of downy mildew Peronosclerospora spp. L. by application of endophytic agents in corn

ABSTRACT This research was carried out to evaluate endophytic biocontrol agents (eBCA) in inducing corn plant resistance to downy mildew Peronosclerospora spp. In this context, the estimation of total phenolic content and peroxidase (POD) enzyme activity was carried out in contrast to control without induction treatments. Corn seed treatment using three eBCA II.D2.2, DC.5, and AC.3 on susceptible and tolerant cultivars in a screenhouse and field showed variation in downy mildew reduction. The results showed that Trichoderma asperellum AC.3 treatment suppressed downy mildew by 2.7–23.0% in the screen house. In the field, resistance induction by applications of Bacillus cereus II.D2.2, Fusarium verticillioides DC.5, and T. asperellum AC.3 suppressed the infection from 23% to 79% on susceptible cultivars. However, the T. asperellum AC.3 treatment reported the highest suppression of 55–79% on tolerant and susceptible cultivars. Resistant induction with F. verticillioides DC.5 increased POD enzyme activity by 300.5% and suppressed the infection by 63% in the field. The pathogen suppression ability through the induction with eBCA was related to triggering the increase of total phenolic content and POD enzyme activity in plant tissues. Applications of B. cereus II.D2.2, F. verticillioides DC.5, and T. asperellum AC.3 suppressed downy mildew infection in the field through the induction of total phenolic content and POD enzyme activity in corn. Meanwhile, the best treatment using T. asperellum AC.3 was lower by 30–70% than the application of synthetic fungicide as control.

Progression of Gummy Stem Blight Epidemics on Watermelon with and without Fungicide Inputs.

Gummy stem blight (GSB), caused primarily by the fungus Stagonosporopsis citrulli in the southeastern United States, affects cucurbits and is particularly destructive on watermelon. Previous epidemiological models of GSB constructed for greenhouse cucumber showed leaf wetness and temperature were the primary and secondary environmental factors, respectively, that explained epidemic progress. The objective of this study was to construct a model that predicted GSB severity on field-grown watermelon based on environmental factors. Disease and weather data from six fungicide experiments in Charleston, South Carolina, in spring and fall 1997 and fall 2017, 2018, 2019, and 2022 were used as inputs. Fungicide treatments were grouped into nonsprayed, protectant (chlorothalonil and mancozeb) and GSB-specific (cyprodinil, difenoconazole and fludioxonil) applications. Cumulative hours of leaf wetness was the primary explanatory variable that modeled the increase in proportion GSB severity ≥2% across all epidemics. Incorporation of temperature or other environmental variables did not improve the model. Fit of the overall model was evaluated with k-fold cross validation, where individual experiments were each excluded from the model fitting process. Slopes of predicted disease progress curves were lowered significantly compared to the nonsprayed treatments by applications of protectant fungicides. Applying GSB-specific fungicides alternated with chlorothalonil further reduced slope values. The model successfully predicted progress of GSB epidemics under different weather patterns and fungicide applications.

Integrating machine learning and change detection for enhanced crop disease forecasting in rice farming: A multi-regional study

Crop diseases are increasingly causing devastating yield losses each year, posing a significant threat to global food security. Currently, fungicide treatment is one of the most effective measures to mitigate these disease-induced yield losses. Accurately predicting disease occurrence, onset timing, and development is critical for optimizing fungicide application schedules to achieve high efficacy. In this study, we compiled weekly disease observations, crop management, and weather data from 207 locations across China, India, and Japan. We compared six machine learning (ML) models for their performance in simulating disease severity. By mimicking disease development curves and trends at early stages, we developed a novel change detection (CD) model, named rolling linear regression (RLR), and combined it with the best-performing ML model to predict the occurrence, severity, and onset dates of four major rice diseases: leaf blast (Magnaporthe oryzae), panicle-neck blast (Magnaporthe oryzae), sheath blight (Rhizoctonia solani), and false smut (Ustilaginoidea virens). Our findings showed that the RandomForestRegressor demonstrated the highest performance in simulating disease severity, with mean absolute errors (MAE) below 0.5 % and root mean square errors (RMSE) below 2.5 %. The RLR model showed a distinct advantage over the other four widely used CD models based on five evaluation metrics. Additionally, the paired RandomForestRegressor+RLR model achieved the highest F1-score, ranging from 0.7 to 0.8, in predicting disease occurrence, outperforming 29 other ML+CD model pairs. Furthermore, the RandomForestRegressor+RLR model predicted onset dates with fewer than 6 error days and accuracies ranging from 74 % to 87 %. Combining ML with CD models not only shows robust generalization across diverse environmental conditions but also proves highly effective for large-scale disease risk forecasting in rice farming regions. The adaptability of ML techniques, when sufficient training data are available, particularly enhances decision support systems aimed at optimizing rice disease management practices for growers across various regions. Our hybrid model thus presents a compelling advancement in the precision agriculture domain, with significant implications for improving disease management strategies for crops beyond rice through timely intervention. This approach can contribute to safeguarding global food security by reducing crop losses due to disease damage.

Sága, a Deep Learning Spectral Analysis Tool for Fungal Detection in Grains-A Case Study to Detect Fusarium in Winter Wheat.

Fusarium head blight (FHB) is a plant disease caused by various species of the Fusarium fungus. One of the major concerns associated with Fusarium spp. is their ability to produce mycotoxins. Mycotoxin contamination in small grain cereals is a risk to human and animal health and leads to major economic losses. A reliable site-specific precise Fusarium spp. infection early warning model is, therefore, needed to ensure food and feed safety by the early detection of contamination hotspots, enabling effective and efficient fungicide applications, and providing FHB prevention management advice. Such precision farming techniques contribute to environmentally friendly production and sustainable agriculture. This study developed a predictive model, Sága, for on-site FHB detection in wheat using imaging spectroscopy and deep learning. Data were collected from an experimental field in 2021 including (1) an experimental field inoculated with Fusarium spp. (52.5 m × 3 m) and (2) a control field (52.5 m × 3 m) not inoculated with Fusarium spp. and sprayed with fungicides. Imaging spectroscopy data (hyperspectral images) were collected from both the experimental and control fields with the ground truth of Fusarium-infected ear and healthy ear, respectively. Deep learning approaches (pretrained YOLOv5 and DeepMAC on Global Wheat Head Detection (GWHD) dataset) were used to segment wheat ears and XGBoost was used to analyze the hyperspectral information related to the wheat ears and make predictions of Fusarium-infected wheat ear and healthy wheat ear. The results showed that deep learning methods can automatically detect and segment the ears of wheat by applying pretrained models. The predictive model can accurately detect infected areas in a wheat field, achieving mean accuracy and F1 scores exceeding 89%. The proposed model, Sága, could facilitate the early detection of Fusarium spp. to increase the fungicide use efficiency and limit mycotoxin contamination.