The application of fungicides in maize by the commonly used overhead spraying technique is more challenging than in small-grain cereals. Especially in later development stages, when the plant has ...reached a considerable height, lower plant organs (e.g., ears) may be insufficiently protected, since a large part of the applied fungicide is deposited on the upper leaves. In contrast, lower plant organs can be reached by the dropleg spraying technique, which allows sub-canopy applications. This study investigated the efficacy of fungicide applications during flowering in forage maize using the overhead and dropleg spraying techniques as well as a combination for the control of Kabatiella zeae and mycotoxin-producing Fusarium species, which can affect leaves and ears, respectively. The efficacy was evaluated in field trials under natural K. zeae and artificial Fusarium inoculum conditions in Northern Germany by measuring disease severities of K. zeae on maize leaves, dry matter yields, and concentrations of the Fusarium mycotoxins deoxynivalenol (DON) and zearalenone (ZEN) at harvest. Fusarium inoculations of main ears at full flowering resulted in significantly higher DON and ZEN concentrations compared to natural Fusarium infections, whereas the dry matter yield was not affected. The strongest disease progressions of K. zeae were determined after flowering on the upper leaves and leaves around the main ear. Disease severities were significantly reduced on the upper leaves by the overhead application and the combination of the overhead and dropleg spraying technique, whereby the three spraying techniques were equally able to decrease the infestation on the yield-essential leaves around the main ear. No differences in dry matter yield were found between the application techniques, but they were significantly higher than in the untreated control. The contamination with DON and ZEN was most effectively reduced by sub-canopy applications using the dropleg technique, whether as a solo application or in combination with the overhead technique. The main ears were reached better with the applied fungicide, reducing Fusarium infections, and therefore, contamination with mycotoxins. The dropleg technique offers an opportunity for improved protection of lower plant organs, especially in tall growing crops. In combination with the overhead spraying technique, the protection of various plant organs along the entire plant with the applied fungicide could be advantageous, especially when different parts of the plant are affected by different fungal diseases.
Black spot disease or Alternaria black spot (ABS) of pecan (Carya illinoinensis) in South Africa is caused by Alternaria alternata. This fungal pathogen impedes the development of pecan trees and ...leads to low yield in pecan nut production. The present study investigated the in vitro effect of six fungicides against the mycelial growth of A. alternata isolates from ABS symptoms. Fungicides tested include Tilt (propiconazole), Ortiva (azoxystrobin), AgTin (fentin hydroxide), and Bellis (boscalid + pyraclostrobin). All fungicides were applied in 3 concentrations (0.2, 1, and 5 μg mLsup.−1). Tilt and Bumper 250 EC containing propiconazole active ingredient (demethylation Inhibitors) were the most effective and inhibited all mycelial growth from up to 6 days post-incubation. The other active ingredients (succinate dehydrogenase inhibitors, organotin compounds, and quinone outside inhibitors) showed 75–85% mycelial growth inhibition. The effective concentration to inhibit mycelial growth by 50% (ECsub.50) was estimated for each isolate and fungicide. The overall mean ECsub.50 values for each fungicide on the six isolates were 1.90 μg mLsup.−1 (Tilt), 1.86 μg mLsup.−1 (Ortiva), 1.53 μg mLsup.−1 (AgTin), and 1.57 μg mLsup.−1 for (Bellis). This initial screening suggested that propiconazole fungicide was the most effective for future field trials test and how these fungicides could be used in controlling ABS disease.
Based on the modification of natural products and the active substructure splicing method, a series of new N-(thiophen-2-yl) nicotinamide derivatives were designed and synthesized by splicing the ...nitrogen-containing heterocycle natural molecule nicotinic acid and the sulfur-containing heterocycle thiophene. The structures of the target compounds were identified through sup.1H NMR, sup.13C NMR and HRMS spectra. The in vivo bioassay results of all the compounds against cucumber downy mildew (CDM, Pseudoperonospora cubensis (Berk.et Curt.) Rostov.) in a greenhouse indicated that compounds 4a (ECsub.50 = 4.69 mg/L) and 4f (ECsub.50 = 1.96 mg/L) exhibited excellent fungicidal activities which were higher than both diflumetorim (ECsub.50 = 21.44 mg/L) and flumorph (ECsub.50 = 7.55 mg/L). The bioassay results of the field trial against CDM demonstrated that the 10% EC formulation of compound 4f displayed excellent efficacies (70% and 79% control efficacies, respectively, each at 100 mg/L and 200 mg/L) which were superior to those of the two commercial fungicides flumorph (56% control efficacy at 200 mg/L) and mancozeb (76% control efficacy at 1000 mg/L). N-(thiophen-2-yl) nicotinamide derivatives are significant lead compounds that can be used for further structural optimization, and compound 4f is also a promising fungicide candidate against CDM that can be used for further development.
Two new metabolites, an α-pyridone derivative, 3-hydroxy-2-methoxy-5-methylpyridin-2(1H)-one (1), and a ceramide derivative, 3-hydroxy-N-(1-hydroxy-3-methylpentan-2-yl)-5-oxohexanamide (2), and a new ...natural product, 3-hydroxy-N-(1-hydroxy-4-methylpentan-2-yl)-5-oxohexanamide (3), along with 15 known compounds including chaetoglobosin C (7) and chaetoglobosin F (8) were isolated from the solid culture of the endophytic fungus Botryosphaeria dothidea KJ-1, collected from the stems of white cedar (Melia azedarach L). The structures were elucidated on the basis of spectroscopic analysis (1D and 2D NMR experiments and by mass spectrometric measurements), and the structure of 1 was confirmed by X-ray single-crystal diffraction. These metabolites were evaluated in vitro for antimicrobial, antioxidant, and cytotoxicity activities. Pycnophorin (4) significantly inhibited the growth of Bacillus subtilis and Staphyloccocus aureus with equal minimum inhibitory concentration (MIC) values of 25 μM. Stemphyperylenol (5) displayed a potent antifungal activity against the plant pathogen Alternaria solani with MIC of 1.57 μM comparable to the commonly used fungicide carbendazim. Both altenusin (9) and djalonensone (10) showed markedly DPPH radical scavenging activities. In addition, stemphyperylenol (5) and altenuene (6) exhibited strong cytotoxicity against HCT116 cancer cell line with a median inhibitory concentration (IC50) value of 3.13 μM in comparison with the positive control etoposide (IC50 = 2.13 μM). This is the first report of the isolation of these compounds from the endophytic B. dothidea.
The evolution and spread of pan-azole resistance alleles in clinical and environmental isolates of
is a global human health concern. The identification of hotspots for azole resistance development in ...the wider environment can inform optimal measures to counteract further spread by minimizing exposure to azole fungicides and reducing inoculum build-up and pathogen dispersal. We investigated the fungicide sensitivity status of soil populations sampled from arable crops and the wider environment and compared these with urban airborne populations. Low levels of azole resistance were observed for isolates carrying the CYP51A variant F46Y/M172V/E427K, all belonging to a cluster of related cell surface protein (CSP) types which included t07, t08, t13, t15, t19, and t02B, a new allele. High levels of resistance were found in soil isolates carrying CYP51A variants TR
/L98H and TR
/Y121F/T289A, all belonging to CSP types t01, t02, t04B, or t11. TR
/Y121F/M172V/T289A/G448S (CSP t01) and TR
/Y121F/T289A/S363P/I364V/G448S (CSP t01), a new haplotype associated with high levels of resistance, were isolated from Dutch urban air samples, indicating azole resistance evolution is ongoing. Based on low numbers of pan-azole resistant isolates and lack of new genotypes in soils of fungicide-treated commercial and experimental wheat crops, we consider arable crop production as a coldspot for azole resistance development, in contrast to previously reported flower bulb waste heaps. This study also shows that, in addition to azole resistance, several lineages of
carrying TR-based CYP51A variants have also developed acquired resistance to methyl benzimidazole carbamate, quinone outside inhibitor and succinate dehydrogenase (Sdh) inhibitor fungicides through target-site alterations in the corresponding fungicide target proteins; beta-tubulin (F200Y), cytochrome
(G143A), and Sdh subunit B (H270Y and H270R), respectively. Molecular typing showed that several multi-fungicide resistant strains found in agricultural soils in this study were clonal as identical isolates have been found earlier in the environment and/or in patients. Further research on the spread of different fungicide-resistant alleles from the wider environment to patients and
can inform optimal practices to tackle the further spread of antifungal resistance in
populations and to safeguard the efficacy of azoles for future treatment of invasive aspergillosis.
As the first isopropanol chiral triazole fungicide, mefentrifluconazole has broad prospects for application. In this study, the stereoselective stability, bioactivity, fate, and biotoxicity were ...systematically investigated. Our results indicated that the stability of mefentrifluconazole enantiomers differed between environmental media, and they were stable in water and sediment in the dark. The bactericidal activity of
-mefentrifluconazole against the four target pathogens was 4.6-43 times higher than that of
-mefentrifluconazole. In the water-sediment system,
-mefentrifluconazole dissipated faster than
-mefentrifluconazole in water; however, its accumulation capacity was higher than that of
-mefentrifluconazole in sediment and zebrafish.
-Mefentrifluconazole induced more differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) in zebrafish than did
-mefentrifluconazole. Multiomics sequencing results showed that
-mefentrifluconazole enhanced the antioxidant, detoxification, immune, and metabolic functions of zebrafish by interacting with related proteins. Based on AlphaFold2 modeling and molecular docking, mefentrifluconazole enantiomers had different binding modes with key target proteins in pathogens and zebrafish, which may be the main reason for the stereoselective differences in bioactivity and biotoxicity. Based on its excellent bioactivity and low biotoxicity, the
-enantiomer can be developed to improve the bioactivity and reduce the risk of mefentrifluconazole.
Pesticides coated to the seed surface potentially pose an ecological risk to granivorous birds that consume incompletely buried or spilled seeds. To assess the toxicokinetics of seeds treated with ...current-use fungicides, Japanese quail (
) were orally dosed with commercially coated wheat seeds. Quail were exposed to metalaxyl, tebuconazole, and fludioxonil at either a low dose (0.0655, 0.0308, and 0.0328 mg/kg of body weight, respectively) or a high dose (0.196, 0.0925, and 0.0985 mg/kg of body weight, respectively). Fungicides were rapidly absorbed and distributed to tissues. Tebuconazole was metabolized into
-butylhydroxy-tebuconazole. All compounds were eliminated to below detection limits within 24 h. The high detection frequencies observed in fecal samples potentially offer a non-invasive matrix to monitor pesticide exposure. With the summation of total body burden across plasma, tissue, and fecal samples, less than 9% of the administered dose was identified as the parent fungicide, demonstrating the importance to monitor both active ingredients and their metabolites in biological samples.
Phytopathogenic fungal infections have become a major threat to agricultural production, food security, and human health globally, and novel antifungal agents with simple chemical scaffolds and high ...efficiency are needed. In this study, we designed and synthesized 38 8-hydroxyquinoline metal complexes and evaluated their antifungal activities. The results showed that most of the tested compounds possessed remarkable
antifungal activity. Especially, compound
exhibited the highest antifungal potency among all target compounds, with EC
values of 0.0940, 0.125, 2.95, and 5.96 μg/mL, respectively, against
,
,
, and
. Preliminary mechanistic studies had shown that compound
might cause mycelial abnormalities of
, cell membrane permeability changes, leakage of cell contents, and inhibition of sclerotia formation and germination. Moreover, the results of
antifungal activity of compound
against
showed that
possessed higher curative effects than that of the positive control azoxystrobin. Therefore, compound
is expected to be a novel leading structure for the development of new antifungal agents.
Fungicides are frequently used during tree fruit bloom and can threaten insect pollinators. However, little is known about how non-honey bee pollinators such as the solitary bee, Osmia cornifrons, ...respond to contact and systemic fungicides commonly used in apple production during bloom. This knowledge gap limits regulatory decisions that determine safe concentrations and timing for fungicide spraying. We evaluated the effects of two contact fungicides (captan and mancozeb) and four translaminar/plant systemic fungicides (cyprodinil, myclobutanil, penthiopyrad, and trifloxystrobin) on larval weight gain, survival, sex ratio, and bacterial diversity. This assessment was carried out using chronic oral ingestion bioassays where pollen provisions were treated with three doses based on the currently recommended field use dose (1X), half dose (0.5X), and low dose (0.1X). Mancozeb and penthiopyrad significantly reduced larval weight and survival at all doses. We then sequenced the 16S gene to characterize the larvae bacteriome of mancozeb, the fungicide that caused the highest mortality. We found that larvae fed on mancozeb-treated pollen carried significantly lower bacterial diversity and abundance. Our laboratory results suggest that some of these fungicides can be particularly harmful to the health of O. cornifrons when sprayed during bloom. This information is relevant for future management decisions about the sustainable use of fruit tree crop protection products and informing regulatory processes that aim to protect pollinators.
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