Drench Treatment Research Articles

Optimization of fermentation conditions for Bacillus velezensis TCS001 and evaluation of its growth promotion and disease prevention effects on strawberries

Bacillus velezensis TCS001 is a novel biocontrol bacterium with broad-spectrum antifungal activity and plant growth-promoting effects, holding great potential for development in agricultural production. This study optimized the fermentation conditions for B. velezensis TCS001 through single-factor experiments combined with response surface methodology, and developed a formulation for TCS001 suspension concentrate (TCS001-SC). The efficacy of TCS001-SC to promote the growth of strawberries and to prevent and control strawberry anthracnose was evaluated. The optimal liquid fermentation condition for TCS001 was determined to be 2.89 % soluble peanut cake powder, 3.0 % glucose, 3.0 % soluble starch, 0.002 % FePO4, 0.006 % KCl, 0.6 % NaCl, 0.05 % MgCl2·6H2O, 0.3 % K2HPO4, 0.15 % KH2PO4, 0.05 % CaCO3, 0.005 % MnSO4, a working volume of 31 % (77.5 mL/250 mL), a rotation speed of 173 r/min, a cultivation temperature of 28°C, an inoculum volume of 1.0 %, and a pH of 7.0. The 15 L fermenter upscale culture achieved a spore count of 9.46 × 109 CFU/mL, which was 2.01 times the spore count of 4.7 × 109 CFU/mL before optimization, and a preliminary TCS001-SC was developed with the fermented broth as the main component. Agar plate confrontation tests showed that TCS001 had antifungal activity against five types of anthracnose fungi, with inhibition rates ranging from 70.3 % to 87.2 %. TCS001-SC could promote the growth of strawberries and induce a rapid defense enzyme response in their leaves, enhancing the plant's resistance to pathogens. After treatment, individual strawberry plants showed significant increases in the number of leaves, fresh weight of stems and leaves, root fresh weight, leaf area, plant height, and the content of POD, SOD, CAT enzymes, GA, IAA, and ABA compared to the control.Additionally, it shows good prevention and control effects against strawberry anthracnose, with a control efficacy of 60.45% after five spray treatments at a concentration of 2 × 107 CFU/mL, which is not significantly different from the efficacy of commercial microbial agents such as Bacillus subtilis wettable powder, subsequent field trials will be conducted to determine its potential as a microbial pesticide. This study provides important support for the future industrial production and application of the strain TCS001.

Dynamic Behavior of Systemic Insecticide Residues in Snapdragons

Pesticide application is used in horticulture to reduce plant damage from organisms such as insects and mites. Systemic insecticides are highly efficacious and readily taken up by plant tissues. However, pesticide-treated plants may impose risks to nontarget insects or other organisms within ecosystems. In this study, insecticide residues in nectar, leaves, and flower petals of the horticulturally significant herbaceous annual snapdragon, Antirrhinum majus (Lamiales: Plantaginaceae), were assessed at two locations over several weeks following foliar and drench treatment with five systemic insecticides. Concentrations of the insecticides were determined by liquid chromatography–mass spectrometry. The independent effects Application Method, Application Rate, and Time were statistically significant among all active ingredients in the three matrices in both sites in California (CA) and New Jersey (NJ). The interaction effects were also generally statistically significant in the CA site but less consistently so in the NJ site, dependent on the active ingredient and matrix. Post hoc analyses found the highest residue concentrations in leaves and the lowest in nectar, a trend generally consistent over time regardless of active ingredient for both the CA and NJ sites. The results of this study are discussed in the context of conserving pollinators and other beneficial insects. It is recommended that similar studies should be implemented in different geographical regions and climates, along with multiyear studies for perennial ornamental plants.

A biostimulant prepared from red seaweed Kappaphycus alvarezii induces flowering and improves the growth of Pisum sativum grown under optimum and nitrogen-limited conditions.

Nitrogen (N) is one of the critical elements required by plants and is therefore one of the important limiting factors for growth and yield. To increase agricultural productivity, farmers are using excessive N fertilizers to the soil, which poses a threat to the ecosystem, as most of the applied nitrogen fertilizer is not taken up by crops, and runoff to aquatic bodies and the environment causes eutrophication, pollution, and greenhouse gas emissions. In this study, we used LBS6, a Kappaphycus alvarezii-based biostimulant as a sustainable alternative to improve the growth of plants under different NO3 - fertigation. A root drench treatment of 1 ml/L LBS6 significantly improved the growth of Pisum sativum plants grown under optimum and deficient N conditions. No significant difference was observed in the growth of LBS6-treated plants grown with excessive N. The application of LBS6 induced flowering under optimum and deficient N conditions. The total nitrogen, nitrate and ammonia contents of tissues were found to be higher in treated plants grown under N deficient conditions. The LBS6 treatments had significantly higher chlorophyll content in those plants grown under N-deficient conditions. The root drench application of LBS6 also regulated photosynthetic efficiency by modulating electron and proton transport-related processes of leaves in the light-adapted state. The rate of linear electron flux, proton conductivity and steady-state proton flux across the thylakoid membrane were found to be higher in LBS6-treated plants. Additionally, LBS6 also reduced nitrogen starvation-induced, reactive oxygen species accumulation by reduction in lipid peroxidation in treated plants. Gene expression analysis showed differential regulation of expression of those genes involved in N uptake, transport, assimilation, and remobilization in LBS6-treated plants. Taken together, LBS6 improved growth of those treated plants under optimum and nitrogen-limited condition by positively modulating their biochemical, molecular, and physiological processes.

309 Evaluation of Encapsulated Megasphaera Elsdenii Ncimb 41125 in an Accelerated Beef Step-up Program and an Acidosis Challenge Model

Abstract A metabolism experiment was conducted to evaluate the effects of daily feeding of encapsulated Megasphaera elsdenii (M. elsdenii) NCIMB 41125 along with a one-time dose of Lactipro NXT (MS Biotec) on dry matter intake (DMI), rumen pH, in vitro lactate disappearance, volatile fatty acid (VFA) concentration, and lactate concentration. Ruminally cannulated crossbred steers (n = 40, initial BW 437 ± 98 kg) were individually fed a finisher diet consisting of 70% steam-flaked corn, 18% modified distillers grain plus soluble, and 7% alfalfa hay. Treatments were control (Con) steers which were given no M. elsdenii and four treatments that received LactiproNXT on day 1 and were given 0 (Drench), 1×106 (Low), 1×107 (Medium), or 1×108 (High) CFU of encapsulated M. elsdenii daily throughout the experiment fed as a top-dress. Adaptation to the finishing diet was accomplished in 19 days for Con steers and 9 days for steers in the Drench, Low, Medium, and High treatments. The experiment included five continuous periods: step-up (d 1-19); finishing (d 20-88); feed restriction (d 89, 24-h full feed restriction); challenge (d 90, cattle were fed at 150% of max DMI from finishing period); and recovery (d 91-94). Data were analyzed using the MIXED procedure of SAS with linear and quadratic effects of dose with drench as the intercept. There were no significant differences for DMI in the step-up, finishing, or challenge period. In the recovery period, DMI was greater for Low, Med, and High compared with Drench (P = 0.07) and there was a tendency for a linear increase in DMI with increasing the dose of M. elsdenii (P = 0.11). Recovery period DMI, expressed as a percentage of pre-challenge intake, was greater (P = 0.05) in steers fed M. elsdenii daily compared with Drench steers, and increased linearly (P = 0.06) as dose of M. elsdenii increased. Rumen pH in steers fed M. elsdenii daily was greater (P < 0.01) during the feeding period and tended to be greater during the challenge (P = 0.14) and recovery (P = 0.11) periods when compared with the Drench treatment. In vitro lactate disappearance tended to be greater (P = 0.13) in steers given M. elsdenii daily when compared with Con and Drench on d 88. For days 90, 91, and 92 combined, a treatment effect was observed for in vitro lactate disappearance with steers in the Low, Med, and High treatments having greater (P < 0.05) disappearance than Con steers, and Med steers having greater (P < 0.05) disappearance than all other treatments. An accelerated step up is possible with the drench and daily feeding of M. elsdenii. Daily feeding of M. elsdenii has a positive effect on cattle during and after an acidosis challenge event.

Strigolactones GR-24 and Nijmegen Applications Result in Reduced Susceptibility of Tobacco and Grapevine Plantlets to Botrytis cinerea Infection.

Priming agents are plant defence-inducing compounds which can prompt a state of protection but may also aid in plant growth and interactions with beneficial microbes. The synthetic strigolactones (±)-GR24 and Nijmegen-1 were evaluated as potential priming agents for induced resistance against Botrytis cinerea in tobacco and grapevine plants. The growth and stress response profiles of B. cinerea to strigolactones were also investigated. Soil drench treatment with strigolactones induced resistance in greenhouse-grown tobacco plants and restricted lesion development. The mode of action appeared to function by priming redox-associated compounds to produce an anti-oxidant protective response for limiting the infection. The results obtained in the in vitro assays mirrored that of the greenhouse-grown plants. Exposure of B. cinerea to the strigolactones resulted in increased hyphal branching, with (±)-GR24 stimulating a stronger effect than Nijmegen-1 by affecting colony diameter and radial growth. An oxidative stress response was observed, with B. cinerea exhibiting increased ROS and SOD levels when grown with strigolactones. This study identified the application of strigolactones as potential priming agents to induce disease resistance in both tobacco and grapevine plants. In addition, strigolactones may alter the ROS homeostasis of B. cinerea, resulting in both morphological and physiological changes, thereby reducing virulence.

Effect of Cyanobacterial Combinations on Peanut Yield

The characteristics of two cyanobacterial strains, Anabaena oryzae and Nostoc muscorum, were studied in order to use them as biofertilizers in a field experiment conducted in the two winter seasons of 2021 and 2022 at the Ismailia Agricultural Research Center Station to study the effect of both strains on peanut plant in sandy soil. Cyanobacterial strains were used individually by coating seed, soil drench, and foliar applications, as well as mixed applications of two strains in various ways. Both cyanobacterial strains morphological examination revealed that they both have heterocysts, nitrogen, phosphorus, and potassium in their culture filtrate, and they were able to produce chlorophyll a and phosphatase enzymes. The results of an agricultural experiment showed that using Nostoc muscorum and Anabaena oryzae separately had a positive effect on peanut plants in a variety of applications, but combining both of these applications with 75% nitrogen increased the growth traits, nutrient contents, and soil biological activities in both peanut plants and their rhizosphere soil. The soil drench treatment with A. oryzae and Nostoc muscorum plus 75% nitrogen produced the highest growth results and peanut yields in a single application. The A. oryzae Soil Drench Application (S) + N. muscorum Foliar Application (F) with 75% N reported the best outcomes in mixed treatments. However, compared to single applications, all blended applications displayed better growth and yield characteristics. The results of the study suggest that employing cyanobacteria in a mixed application will enhance its advantages over a single use.

Root-knot nematode pathogen suppression in eggplant using antagonistic fungi

BackgroundMeloidogyne incognita (Kofoid and White) Chitwood is a major pest of eggplant in Pakistan. The second-stage juveniles (J2s) feed on the roots of eggplant. Damaged roots swell and the plant exhibits stunted growth. Mostly farmers rely on the use of broad-spectrum nematicides. However, due to hazardous effects on the environment and non-target species, its application is greatly criticized. Fungal biocontrol agents have been long used for curtailing root-knot nematode infections. The present study was conducted to determine the virulence of four fungal biocontrol agents against M. incognita under laboratory and greenhouse conditions.ResultsThe in vitro results revealed that Trichoderma harzianum significantly caused 77.60% egg inhibition, followed by Pochonia chlamydosporium (53.0%) at 1:1 concentration after 72 h. The maximum J2s mortality was achieved by T. harzianum (82.0%), followed by P. chlamydosporium (70.20%) at 1:1 concentration after 72 h. The in-planta examination carried out at a greenhouse demonstrated that the soil drench treatment of fungal biocontrol agents significantly suppressed M. incognita parameters and upraised the eggplant growth. The mean least number of galls (22.25) was in T. harzianum treated plants, while the control had (206.8) galls. Likewise, T. harzianum curtailed the least egg masses to 35.75 and swollen females to 21.12 than control negative (224.13 egg masses and 182.75 swollen females).ConclusionT. harzianum was the best agent to control M. incognita (J2s) effectively, followed by P. chlamydosporum. T. harzianum may be a contribution to the biological control of M. incognita in Pakistan.

Soil drenching and foliar spray with bioagents for reducing wheat leaf diseases under natural field conditions

Foliar diseases, like powdery mildew, septoria leaf blotch (SLB) and stem rust, affect wheat plants causing severe yield losses. Biofertilizers Pseudomonas fluorescens Migula (NRC2041) and Bacillus subtilis Ehrenberg (NRC313) or the arbuscular mycorrhizal fungi Glomus mosseae Tul. & C. Tul. (NRC212A) and G. fasciculatum Tul. & C. Tul. (NRC212B) were used for soil treatment followed by foliar spray with Trichoderma harzianum or P. fluorescens to manage severity of wheat foliar diseases under field conditions for two successive growing seasons. Under field conditions, at all soil drench and foliar application treatments, Sids 14 was the most sensitive cultivar for high disease severity followed by Misr 2 and Giza 168. Also, the obtained results showed that the most effective treatments were soil drench with mycorrhizae followed by foliar spray with either T. harzianum or P. fluorescens. Meanwhile, the fungicide Amistar showed a superior reduction in disease severity compared to other applied treatments. In addition, the increased yield was correlated to the decreased severity of the recorded diseases. The present study suggests using bioagents for reducing the severity of wheat leaf diseases and increasing the grain yield under field conditions.

Effects of an Ascophyllum nodosum seaweed extract application dose and method on growth, fruit yield, quality, and water productivity of tomato under water-deficit stress

• We evaluated the effect of Ascophyllum nodosum seaweed extract (ASE) formulation on tomato under drought stress. • Tomato yielded more when ASE was applied at 5 mL L –1 as a soil drench than as a foliar spray. • Water productivity was maximized at 5 mL L –1 for all soil moisture levels. • Soil or foliar application of ASE at 5 mL L −1 could be regarded as an optimum dose. • ASE at 5 mL L −1 as a soil drench is more effective than its application as a foliar spray. The scarcity of irrigation water is a major threat restricting growth and productivity of almost all agronomic and horticultural crops. The tomato ( Solanum lycopersicum L.) is no exception. Seaweed extracts are widely used as biostimulants for the improvement of plant growth and development. Two independent pot experiments were conducted to find out the best soil drench or foliar spray dose of a commercial Ascophyllum nodosum seaweed extract (ASE) formulation (Amino Seaweed, SV Group, Bangkok, Thailand) on growth, physiological and biochemical parameters, fruit yield, quality, and water productivity of tomato under water-deficit stress. The commercial ASE formulation was applied in five doses (0, 2.5, 5, 10, and 20 mL L −1 ) as a soil drench (Experiment 1) or as a foliar spray (Experiment 2) under three soil moisture levels (50, 75, and 100% field capacity [FC]). Severe soil moisture deficit of 50% FC caused a 67 and 52% reduction in fruit yield, 11 and 11% reduction in fruit length, 25 and 29% decrease in leaf relative water content, while total soluble solids content was increased by 38 and 49% compared with 100% FC in Experiments 1 and 2, respectively. Soil drench or foliar spray of the commercial ASE formulation at 5 mL L −1 was effective at all soil moisture levels. Soil drench of the commercial ASE formulation at 5 mL L −1 resulted in 225% higher fruit yield in comparison to the untreated plants at 50% FC, whereas its application as a foliar spray resulted in 271% higher fruit yield in comparison to the untreated plants subjected to severe water-deficit stress (50% FC). Water productivity was found lower for the untreated plants regardless of soil moisture levels in both application methods; however, it was maximized at 5 mL L –1 for all soil moisture levels. The beneficial effects of 5 mL L –1 ASE formulation dose was also evident in physiological/biochemical traits and fruit quality of tomato regardless of application methods. Tomato yielded more when the commercial ASE formulation was applied at 5 mL L –1 as a soil drench (523.3 g plant –1 fruit yield) rather than as a foliar spray treatment (397.1 g plant –1 fruit yield). The results indicate that (i) 5 mL L −1 could be regarded as an optimum dose of the commercial ASE formulation for tomato applied either as a soil drench or foliar spray and (ii) exogenous application of the commercial ASE formulation at 5 mL L −1 as a soil drench treatment is more efficient, especially in fruit yield improvement, compared with its application as a foliar spray and, therefore, this technique holds promise for tomato cultivation under moderate water-deficit stress.

The effects of oral drenching with Co or vitamin B12, drenching frequency and Co via rumen bolus on plasma vitamin B12 concentration in weaned lambs

Weaned lambs (n = 88) were stratified by sex and body weight (BW) and allocated at random to 1 of 10 treatments for 12 weeks (consecutive 6-week periods), to evaluate the effects of supplementation with Co or vitamin B12 (B12) on the concentrations of B12 in blood plasma. The treatments were: no supplementation (Control); rumen bolus containing Co only (Bolus); and oral administration of a liquid solution (Drench) containing Co or B12 at intervals of 1, 2, 3 or 6 weeks. One bolus (expected Co release [by leaching] of 0.8 mg/day for 4 months) was administered to the bolus group at the initiation of the study (day 0). The lambs on the drench treatments received totals of 63 mg Co (as CoSO4·7H2O) or 34.5 mg B12 over each 6-week period; drench concentrations were 2.1 mg/ml and 2.3 mg/ml for Co and B12, respectively. The lambs were managed in a rotational-grazing system on predominately perennial ryegrass swards. Blood samples were collected weekly (immediately prior to treatment administration), starting on day 0, and plasma was analysed for B12 and Co. Lambs on the Co-drench treatments had higher B12 concentrations (P < 0.001) than the Control in both 6-week periods but the difference exhibited a quadratic decline in both periods as the drenching interval increased (P < 0.001). Drenching with B12 increased plasma B12 concentration in both periods but the difference only reached significance (P < 0.05) in the second period and the effect of drenching frequency was not significant in either period. Lambs on the Co-drench had higher (P < 0.01) plasma B12 concentrations than lambs on the B12-drench treatments, and the control. Bolus lambs had a higher plasma B12 concentration (P < 0.01) than lambs drenched with Co at 2-, 3- or 6-week intervals in the first 6-week period but did not differ (P > 0.05) from these treatments in the second period. Lambs on the Bolus treatment had a higher plasma B12 concentration than Control lambs over the first (P < 0.001) and second (P < 0.05) periods. It is concluded that drenching with Co is more effective than drenching with B12, in terms of the effect on plasma B12 concentration. Drenching with Co at intervals of 1 or 2 weeks was more effective than drenching at intervals of 3 or 6 weeks. While the bolus treatment was effective in increasing plasma B12 concentration compared to Control over weeks 1 to 12, the difference between these treatments declined significantly over time.

Comparing imidacloprid, clothianidin, and azoxystrobin runoff from lettuce fields using a soil drench or treated seeds in the Salinas Valley, California

Neonicotinoid insecticide use has increased over the last decade, including as agricultural seed treatments (application of chemical in a coating to the seed prior to planting). In California, multiple crops, including lettuce, can be grown using neonicotinoid treated seeds or receive a direct neonicotinoid soil application (drenching) at planting. Using research plots, this study compared pesticide runoff in four treatments: (1) imidacloprid seed treatment; (2) clothianidin seed treatment; (3) imidacloprid drench and an azoxystrobin seed treatment; and (4) a control with no pesticidal treatment. Neonicotinoid and azoxystrobin concentrations were measured in surface water runoff during six irrigations events in the 2020 growing seasons. Results showed runoff concentrations up to 1308 (±1200) ng L−1 for imidacloprid drench treatment, 431 (±100) ng L−1 for clothianidin seed treatment, 135 (±60) ng L−1 for imidacloprid seed treatment, and 13 (±10) ng L−1 for azoxystrobin seed treatment (treatments averaged). The percent of applied mass in runoff over the entire sampling period varied by compound; the imidacloprid seed treatment and drench were similar (0.015 and 0.019%, respectively) to the clothianidin seed treatment (0.036%) while the azoxystrobin seed treatment was much higher (15%). Although the proportion of imidacloprid in runoff was similar for imidacloprid treatments, the mass applied during soil drench was > 4x the amount applied from the imidacloprid seed treatment. Surface soils were collected before planting and at the end of the trial. The neonicotinoids were detected in soil throughout the study and average maximum concentrations were 9–13 ng g−1; azoxystrobin was detected in only two soils at concentrations up to 0.57 ng g−1. These results elucidate the comparative mass runoff resulting from planting treated seed and soil drench applications and highlight the value of additional work to characterize off-site transport from the many commodities that may be utilizing treated seeds.

Management of Potato Bacterial Wilt Disease Using Abiotic Treatments

Bacterial wilt disease caused by Ralstonia solanacearum (Smith) Yabuuchi is one of the most important bacterial diseases in the world. This study aimed to test some chemical compounds such as bactericides that were applied to control bacterial wilt disease under artificial inoculation conditions and their effects on the yield of potatoes under greenhouse conditions.In vitro, tested chemical compounds (Cefalexin, Gentamycin, and Copper sulphate) inhibit the growth of R. solanacerum compared with control treatment. Copper sulphate was the most effective where the Inhibition zone diameter was 6.0 to7.4mm compared with cefalexin and gentamycin, 3.6 to 5.8mm respectively, but cefalexin was moderately effective 4.2 to 5.8mm and gentamycin was less effective 3.6 to 5.8mm against the pathogen. Inhibition zone diameter was increased with increasing concentrations of tested chemical compounds. Greenhouse experiments showed that the chemical compounds used reduced the severity of potato bacterial wilt disease and increased potato yield compared with control treatment. When using Cefalexin, the mean of wilted shoots was 20.5 and the severity of disease 16.3, while when using Gentamycin as an Abiotic, the mean of wilted shoots was 22.8 and severity of disease 17.6 which was the most effective compared with Copper sulphate treatment were wilted shoot was 31.8 and severity of disease 29.6. The application of tested chemical compounds as soil drench treatment led to a percentage of infection which ranged from16.4 to19.0 more effective than tuber treatment where the percentage of infection ranged from 18.4 to 20.1.

Pseudomonas aeruginosa isolate PM1 effectively controls virus infection and promotes growth in plants.

A bacterial isolate PM1 obtained from the rhizosphere of healthy plants was identified as Pseudomonas aeruginosa by biochemical characteristics and 16S rRNA gene sequence (GenBank ID OL321133.1). It induced resistance in Nicotiana tabacum cv. Xanthi-nc and Cyamopsis tetragonoloba, against Tobacco mosaic virus (TMV) and Sunn-hemp rosette virus (SRV), respectively. Foliar treatment with isolate PM1 curbed TMV accumulation in susceptible N. tabacum cv. White Burley. PM1 was more effective as a foliar than a root/soil drench treatment, evident through a comparative decrease in ELISA values, and reduced viral RNA accumulation. Foliar and soil drench treatment with PM1 resulted in a disease index of 48 and 86 per cent, and a control rate of 48.9 and 8.5 per cent, respectively. PM1 exhibited phosphate solubilization, produced siderophores, auxins, HCN, and ammonia, all important plant growth-promoting traits. Foliar treatment with PM1 enhanced growth in tobacco, while its volatiles significantly promoted seedling growth in C. tetragonoloba. Of the several metabolites produced by the isolate, many are known contributors to induction of systemic resistance, antibiosis, and growth promotion in plants. Soluble metabolites of PM1 were less effective in inducing antiviral resistance in N. tabacum cv. Xanthi-nc in comparison with its broth culture. PM1 and its metabolites were antagonistic to Gram-positive Bacillus spizizenii and Staphylococcus aureus, and fungi Fusarium oxysporum, Aspergillus niger, and Rhizopus stolonifer. Its volatiles were inhibitory to F. oxysporum and R. stolonifer. Thus, PM1 exhibited considerable potential for further evaluation in plant virus control and production of diverse metabolites of use in agriculture and medicine.

Lethal effect of ethanol on Solenopsis invicta Buren and economic fish

AbstractThe red imported fire ant (RIFA), Solenopsis invicta Buren, is an invasive pest species worldwide in many countries and regions. At present, its control mainly depends on synthetic insecticides. Although synthetic insecticides have the advantages of efficacy and convenience, their widespread use has a negative impact on the diversity of local arthropods. Ethanol is widely used as a disinfectant and has been consumed by people, but its insecticidal effect has not yet been evaluated. Here, the control effect of ethanol on the RIFA and its toxicity on four fish species were evaluated. The results exhibited that mortalities of all tested adult castes reached 100% after soaking in 70% v/v ethanol solution for one hour. All reproductive and worker pupae survived at 60% v/v ethanol treatment. In the soaking plus fumigation experiment, all adult castes and brood except female pupae were sensitive to 30% v/v ethanol solution. Conversely, female pupae showed the highest resistance to ethanol. More than 60% v/v ethanol concentration was needed to cause its 100% mortality. In the field experiment, 25% v/v and 50% v/v ethanol solution resulted in 70% and 80% reduction of mound 14 d after drench treatment, respectively. The ethanol vapour in the nest soil was higher than 80 ppm after 72 h of mound drench in the field with 25% v/v ethanol solution. Moreover, 30% v/v ethanol solution did not adversely affect the survival of four fish species exposed to the solution for a short time. This study suggests that mound drench can be alternatively employed with ethanol as a green organic solvent to control RIFA.

Organic Acid Sanitizers for Natamycin and Other Fungicides in Recirculating Application Systems for Citrus Postharvest Decay Management.

Natamycin is a new postharvest biofungicide for citrus and some other fruit crops in the United States that can be effectively used in recycling drench or flooder treatments. These applications necessitate sanitation of the fungicide solution to ensure that it remains free from contamination by bacteria that are potentially human pathogens. During invitro experiments, heated (48°C) citric acid (1,100 or 2,200 μg/ml) amended with sodium dodecylbenzenesulfonate (SDBS) (60 or 120 μg/ml, respectively) significantly reduced the viability of a nonpathogenic strain of Escherichia coli in natamycin solutions by >5 log10 compared with the control. During laboratory studies with Penicillium digitatum-inoculated lemon fruit, 1,000 μg/ml of natamycin mixed with 1,000 μg/ml of lactic acid or citric acid and with or without SDBS (55 μg/ml) effectively and significantly reduced green mold. Natamycin mixed with lactic acid at ≥2,000 μg/ml, however, caused fruit injury, resulting in browning and rind pitting. Natamycin was incompatible with peroxyacetic acid, resulting in reduced efficacy against green mold. Sodium hypochlorite mixed with natamycin lost its toxicity to E. coli; however, the performance of natamycin was not affected. With heated (average 49°C) drench treatments on an experimental packing line, natamycin (1,000 μg/ml), fludioxonil (300 μg/ml), or azoxystrobin (300 μg/ml) mixed with citric acid (1,000 μg/ml) and SDBS (55 μg/ml) were effective against green mold without fruit injury. At a pH between 3.6 and 3.8, citric acid-SDBS significantly reduced the viability of E. coli by approximately 4 log10 in mixtures with fludioxonil or azoxystrobin, but not with natamycin. However, natamycin at 1,000 μg/ml mixed with 2,000 μg/ml of citric acid and SDBS (55 μg/ml) significantly reduced E. coli counts by >4 log10 within 4 min when the pH was maintained between 3.0 and 3.3, and the efficacy of the fungicide was retained. The use of citric acid with a surfactant can be a viable alternative sanitation method for natamycin in citrus packinghouses utilizing heated recirculating fungicide systems.

The Influence of Copper Homeostasis Genes copA and copB on Xylella fastidiosa Virulence Is Affected by Sap Copper Concentration.

Xylella fastidiosa is a xylem-limited plant pathogenic bacterium that causes diseases worldwide in crops such as grape, citrus, and olive. Although copper (Cu)-containing compounds are not used for management of X. fastidiosa-caused diseases, they are widely used in X. fastidiosa hosts in vineyards and orchards. The accumulation of Cu in soils and, therefore, plant saps, could be a challenge for X. fastidiosa survival. Here, the molecular basis of Cu homeostasis was studied in relation to virulence. Although homologous Cu-related genes copA (X. fastidiosa loci PD0100) and copB (PD0101) have been characterized in other bacteria, their functions differ among bacterial species. In vitro, both copA and copB mutants were more sensitive to Cu than the wild-type (WT) strain. Interestingly, the copA mutant was more sensitive to Cu shock, while the copB mutant was more sensitive to chronic Cu treatments. In tobacco greenhouse experiments with normal watering, both mutants reduced virulence compared with WT. But when Cu was added as a drench treatment, both copA and copB mutants had increased disease severity approximately 20 and 50% compared with mutants without Cu added, respectively, which were significantly higher than the approximately 5% observed for WT under the same conditions. These results indicate that the pathogen's Cu homeostasis affects virulence and is influenced by Cu concentration in the environment. Understanding Cu homeostasis in X. fastidiosa will help discern the outcome of Cu treatments and the adaptation of this pathogen to the xylem of plants that have been exposed to high Cu concentrations because of agricultural practices.

The effects of supplementation with cobalt, and method of administration, on ewe reproduction and offspring performance to weaning

The concentration of Co in the herbage of a large proportion of grassland farms in Ireland is lower than that required by sheep. The effects of supplementing ewes with Co, and method of supplementation, on ewe and offspring performance, were evaluated over 2 years. The ewes (359 in year 1, 241 in year 2), representing 3 genotypes, were allocated to one of 3 treatments. The treatments were: Control - no supplementation; Drench – Co supplementation via oral drench (31.5 mg Co as CoSO4•7H2O) administered every 14 days; Bolus – Co supplementation via rumen bolus (effective life of ∼6 months) that only contained Co as CoSO4•7H2O with an expected Co release rate of 0.6 mg/day in year 1 and 1 mg/day in year 2. Drench treatment was administered from 7 weeks pre joining, until 6 weeks prior to expected lambing date (early – to mid - March). One bolus was administered to ewes on the bolus treatment at the start of the study (day 0) each year. The ewes were managed as one flock in a rotational-grazing system until housing in early December each year; they were shorn at housing and offered grass silage ad libitum plus a concentrate supplement during late pregnancy. Ewes and lambs were put to pasture within 3 days of lambing. Supplementation with Co, via drench or bolus, increased the concentration of Co (p< 0.001) and vitamin B12 in ewe plasma at ∼day 50 and ∼day 100 of pregnancy and these effects were generally greater for Drench than Bolus treatments. Supplementary Co had no effect (p > 0.05) on ewe BW or body condition score at joining (day 49), mid-pregnancy, lambing, 5 weeks post lambing or weaning. Likewise, supplementation had no effect (p > 0.05) on litter size, lamb mortality or number of lambs reared per ewe joined, or on lamb BW at birth or weaning. The only significant animal-performance difference detected between the Bolus and Drench treatments concerned the incidence of lambs classified as ‘born dead or died within 24 h of birth’ (3.1% for Drench, 6.5% for Bolus; p < 0.05). It is concluded that, whilst supplementing ewes (high proportion whom (30 to 60%) had marginal plasma B12 status) with Co from 7 weeks pre-joining until late pregnancy increased plasma Co and vitamin B12 concentrations and reduced the proportion classified as having marginal or low Co status. There was no effect on ewe or progeny performance.

Fungicide Efficacy Against Pseudoperonospora humuli and Point Mutations Linked to Carboxylic Acid Amide Resistance in Michigan.

Hops have expanded as a niche crop in Michigan and other production areas in the eastern United States, but growers in these regions face annual downy mildew outbreaks incited by Pseudoperonospora humuli, exacerbated by frequent rainfall and high relative humidity. We evaluated the efficacy of foliar- and drench-applied fungicides against downy mildew and examined Michigan isolates for point mutations linked to carboxylic acid amide (CAA) resistance. Disease severity and density were assessed weekly in 2016 and 2017 in nontrellised research hop yards in Michigan. Area under the disease progress curve values for disease severity were significantly lower for plants treated with oxathiapiprolin, ametoctradin/dimethomorph, fluopicolide, cyazofamid, or mandipropamid (90.6 to 100% control) compared with those treated with fosetyl-Al (64.3 to 93.0% control) at both locations for both years. Drench treatments of fluopicolide and oxathiapiprolin/mefenoxam reduced disease density and severity at both locations but were only moderately effective (76.4 to 91.5% control). To assess CAA resistance, the cellulose synthase CesA3 gene was aligned using reference downy mildew species and primers designed to amplify the 1105 and 1109 amino acids. Point mutations conferring CAA resistance were not detected at these loci for sporangia from 42 symptomatic shoots collected from 11 commercial hop yards. These efficacy results for hop downy mildew are needed to guide disease recommendations in this expanding Michigan industry. The absence of resistant genotypes indicates that Michigan growers can continue to utilize CAA-containing commercial fungicides as part of an overall downy mildew management program.

Retrospective Evaluation of Claw Lesions, Inflammatory Markers, and Outcome after Abomasal Rolling in Cattle with Left Displacement of the Abomasum

Simple SummaryLameness is a major welfare problem in cattle and is often diagnosed concurrent to left displacement of the abomasum. Lame cattle prefer to lie on the affected leg, and laterality of lying may have an effect on the etiology of left displacement of the abomasum. The objective of this study was to investigate the possible association between laterality of claw lesion and presence of left displacement of the abomasum. For this study, the data of 252 cattle were analyzed retrospectively. Inclusion criteria were: a diagnosis of left displacement of the abomasum and diagnostic examination of claw lesions during hospitalization at the clinic. There was no association between laterality of claw lesion and left displacement of the abomasum. Cattle with a claw lesion in their right limbs were not diagnosed with left displacement of the abomasum more often than cattle with claw lesions in their left limbs. A total of 46.4% of cattle were diagnosed with at least one claw lesion. These results emphasize the importance of the prevention of claw lesions, especially in the post-partum period, to improve cattle welfare.Lameness is often diagnosed in cattle with left displacement of the abomasum (LDA). Laterality of lying has an effect on the etiology of LDA, and lame cows prefer to lie on the affected limb. The objective of this study was to investigate the possible association between laterality of claw lesion and presence of LDA. The medical records of 252 cattle presented with a diagnosis of LDA and subjected to a diagnostic examination of claw lesions over a period of 11 years (2009–2019), were analyzed retrospectively. Data were evaluated for presence and localization of claw lesion, concentrations of inflammatory markers, and abomasal rolling as therapy. At least one claw lesion was diagnosed in 46.4% of cattle. There was no association between laterality of claw lesion and LDA. Presence of claw lesion or oral drench and/or analgesic treatment did not have an effect on occurrence of relapse. A high number of cattle was diagnosed with both LDA and claw lesions. Focus should lie on preventing painful claw lesions in the dry and the early post-partum period. The high recurrence rate after abomasal rolling suggests that abomasal rolling should only be considered as a therapy for temporary relief, and surgical procedures should be discussed with farmers.

Dissipation and transformation of the diamide insecticide cyantraniliprole in ornamental snapdragon (Antirrhinum majus)

Dissipation and transformation of cyantraniliprole, a new diamide class of insecticides, were investigated under greenhouse conditions, using snapdragon (Antirrhinum majus) as the model plant. Dissipation of cyantraniliprole in treated leaves was found to be dependent upon application methods (foliar spray versus soil drench) and doses (high versus low dose), with the parent insecticide being the major residue at various sampling points. A high-dose foliar application resulted in pesticide residue of 6.7–23.8 μg/g foliar fresh weight over 8 weeks of treatments, while in soil drench treatment the residue varied from 0.8 to 1.4 μg/g. However, the residue contents were similar between the two application methods at a low application dose. The transformation pathways of cyantraniliprole were primarily intramolecular rearrangements, with IN-J9Z38 being the major metabolite across treatments. Several other metabolites were also identified, some of which were unique to the application methods. Out of total 26 metabolites tentatively identified in this study, 10 metabolites were unique to foliar application, while six metabolites were unique to soil drench. In addition to plant-mediated biotransformation, photodegradation of the parent compound was identified as a potential mechanism in foliar application.