Suitability of Formulated Entomopathogenic Fungi Against Hibiscus Mealybug, Nipaecoccus viridis (Hemiptera: Pseudococcidae), Deployed Within Mesh Covers Intended to Protect Citrus From Huanglongbing.

Mesh exclusion bags are increasingly being adopted by Florida citrus growers to protect young citrus trees from Asian citrus psyllid, Diaphorina citri Kuwayama, and Huanglongbing disease. These mesh bags exclude larger insects such as D. citri but may allow entry of minute insects. Hibiscus mealybugs, Nipaecoccus viridis (Newstead), have been observed thriving in the micro-habitat created by these covers on trees. Entomopathogenic fungi (EPF) and insect growth regulators (IGRs) are effective against several mealybug species under various growing conditions, but their efficacy against N. viridis or within the microclimate within exclusion bags is unknown. Therefore, we evaluated various formulations of entomopathogenic fungi with and without IGR against N. viridis using laboratory bioassays. We then conducted semifield bioassays to determine effectiveness of EPF formulations alone and in combination with an IGR applied to citrus trees enveloped within mesh bags under field conditions. Survival probabilities of N. viridis nymphs exposed to all Beauveria bassiana-based products tested were comparable to malathion under laboratory conditions and reduced survival as compared to controls (water only). Under field conditions, mortality of N. viridis nymphs on leaves sprayed with each fungal formulation tested was significantly greater than on control treatments (Water, Suffoil X, 435 oil) up to four weeks post application. There were no differences in the colony forming units per leaf area amongst all fungal treatments. Formulated B. bassiana-based products applied alone or combined with an IGR should be effective tools for managing N. viridis populations on young citrus trees protected with mesh exclusion bags.

Evaluation of spray pattern uniformity using three unique analyses as impacted by nozzle, pressure, and pulse-width modulation duty cycle.

BACKGROUND: The increasing popularity of pulse-width modulation (PWM) sprayers requires that application interaction effects on spray pattern uniformity be completely understood to maintain a uniform overlap of spray, thereby reducing crop injury potential and maximizing coverage on target pests. The objective of this research was to determine the impacts of nozzle type (venturi vs. non-venturi), boom pressure, and PWM duty cycle on spray pattern uniformity. Research was conducted using an indoor spray patternator located at the University of Nebraska-Lincoln in Lincoln, NE, USA. Coefficient of variation (CV), root mean square error (RMSE), and average percent error (APE) were used to characterize spray pattern uniformity. RESULTS: Generally, across nozzles and pressures, the duty cycle minimally impacted the CV of spray patterns. However, across nozzles and duty cycles, increasing pressure decreased CV values, resulting in more uniform spray patterns. The RMSE values typically increased as pressure and duty cycle increased across nozzles. This may be the result of a correlation between RMSE values and flow rate as RMSE values also increased as nozzle orifice size increased. Generally, APE increased as the duty cycle decreased across nozzles and pressures with significant increases (40%) caused by the 20% duty cycle. Within non-venturi nozzles, increasing pressure reduced APE across duty cycles, while venturi nozzles followed no such trend. CONCLUSION: Overall, results suggest PWM duty cycles at or above 40% minimally impact spray pattern uniformity. Further, increased application pressures and the use of non-venturi nozzles on PWM sprayers increase the precision and uniformity of spray applications. © 2019 Society of Chemical Industry.

Impact of sensor-controlled variable-rate fungicide application on yield, senescence and disease occurrence in winter wheat fields.

BACKGROUND: Field experiments examining target-oriented variable-rate fungicide spraying were performed in 2015 and 2016. The spray volume was adapted in real time to the local green coverage level of winter wheat (Triticum aestivum L.), which was detected using a camera sensor. RESULTS: Depending on the growth heterogeneity in the three strip trials in 2015, fungicide savings in the sensor-sprayed strip compared with the adjacent uniformly sprayed strip were 44%, 45% and 1%. In the 2016 field trial, the saving was 12%. There was no greater level of senescence or disease occurrence, and no higher yield losses in the camera-controlled variable-rate sprayed strips compared with the adjacent uniformly sprayed strips. CONCLUSIONS: From an ecological and economical point of view, sensor-controlled variable-rate spraying technology, which uses the level of green crop coverage as the plant parameter to adapt the spray volume locally, can be an alternative to the common practice of uniform spraying. © 2017 Society of Chemical Industry.

Estimate, a New iPad Application for Assessment of Plant Disease Severity Using Photographic Standard Area Diagrams.

Assessment of disease severity is a foundational component of plant pathology and essential for robust disease management. Researchers often estimate disease severity using standard area diagrams (SADs) that are reference images representing disease severity in percentage increments. SADs provide assessments of disease severity that are more accurate, precise, and reliable than other methods. Although specific SADs have been constructed for many plant diseases, they often depict severity in unrealistic black-and-white or grayscale illustrations. SADs are also usually printed, static references that can burden data collection in the field and require data to be transferred manually to a computer spreadsheet for manipulation. This data entry process and verification are prone to errors and require additional inputs of time and labor. We developed a new iPad application (app) called Estimate for researchers and crop managers for their use on a mobile device at the field-level for assessing plant disease severity in order to collect data or aid in treatment decisions. The app is a repository for digital, photographic SADs and offers savings in time for data collection and processing. Estimate allows users to select a disease from a prepopulated list and specify the reference disease images in either logarithmic or linear intervals. Data may be collected as the midpoint of an interval (ordinal) or as 1% increments (continuous). Users then select among photographic images by touching those that best match the observed disease severity on successive samples. Estimate allows data entry at the plant and leaf hierarchical levels within plots and subplots. Alternatively, data may be collected on single sampling units with an undefined experimental design (i.e., 1 to x leaves). The user may inspect and e-mail the final data in comma-separated values format for analysis using conventional spreadsheet software. Estimate was released with SADs for assessing the severity of Cercospora leaf spot in red and yellow table beet cultivars. A list of collaborators and up-to-date list of SADs included in Estimate is available at http://evade.pppmb.cals.cornell.edu/estimate/ . SADs for other diseases will be added to Estimate as they become available. Estimate is available for free download from iTunes ( https://itunes.apple.com/WebObjects/MZStore.woa/wa/viewSoftware?id=1193605571&mt=8 ) and is compatible with an iPad Air 2 or equivalent using iOS 9.0 or greater.

Development of an Attract-and-Kill Strategy for Drosophila suzukii (Diptera: Drosophilidae): Evaluation of Attracticidal Spheres Under Laboratory and Field Conditions.

Drosophila suzukii Matsumura (Diptera: Drosophilidae) is an invasive, polyphagous fruit fly that attacks soft-skinned fruits. Originally from Asia, D. suzukii has successfully invaded the United States and the European and South American countries. At present, calendar-based insecticide applications are used to combat D. suzukii. Here, we evaluate a behaviorally based attract-and-kill management technique using attracticidal spheres to reduce D. suzukii infestations in raspberries. In laboratory bioassays aimed at identifying effective toxicants, attracticidal spheres containing dinotefuran at 1.0% a.i. killed 100% of D. suzukii within 5 min. Spinetoram, spinosad, permethrin, lambda-cyhalothrin (CS) and lambda-cyhalothrin (WG), all at 1.0% a.i., killed 100% of D. suzukii within 24 h. In field trials, statistically equivalent infestation rates were recorded in raspberry plots protected by attracticidal spheres containing 1.0% a.i. spinetoram compared with standard weekly insecticide applications. In field trials using 1.0% a.i. dinotefuran, attracticidal spheres decreased D. suzukii infestations compared with control plots, but insecticide applications were more effective at reducing D. suzukii infestations, although differences in harvesting practices likely affected fly population densities and infestation rates in both years. Attracticidal spheres effectively attract and kill D. suzukii and reduce infestations rates under field conditions, indicating that this behavioral strategy holds promise in D. suzukii management.

Dust drift reduction effect of an air conveyor kit (dual-pipe deflector) mounted on different maize pneumatic drills.

BACKGROUND: All maize drills produce a fine dust due to the seed coating abrasions that occur inside the seeding element. The air stream generated by the fan of pneumatic drills - necessary to create a depression in the sowing element of the machine and to guarantee correct seed deposition - can blow away the solid particles detached from the seeds. In order to reduce this phenomenon, a coated maize seeds company (Syngenta®) has set up an ad hoc dual-pipe deflector kit that easily fits different pneumatic drills (also old drills). In this study, the efficiency of this kit and the influence of different drill types on the kit's performance in reducing environmental pollution were evaluated using three different pneumatic seed drill models. RESULTS: The research showed that a dual-pipe deflector installed on a drill in standard configuration did not change the seeder performance, and by using this kit on pneumatic drills, irrespective of their design, it is possible to reduce by up to 69% the amount of dust drift in comparison with the conventional machine set-up. CONCLUSION: The dual-pipe deflector, under the conditions employed in the present experiments, showed good performance with all types of maize pneumatic drill used. Irrespective of the seeder model on which it is mounted, it is able to obtain similar results, indicating its high operational versatility. © 2016 Society of Chemical Industry.

Simulating the fate and transport of nursery-box-applied pesticide in rice paddy fields.

BACKGROUND: The Pesticide Concentration in a Paddy Field model (PCPF-1) was modified by adding a root zone compartment to simulate nursery-box-applied (NB-applied) pesticide. The PCPF-NB model was validated for predicting the concentrations of NB-applied fipronil and imidacloprid in rice paddy fields using two treatment methods: before transplanting (BT) and at sowing (AS). Uncertainty and sensitivity analyses were used to evaluate the robustness of the concentrations predicted by the model. RESULTS: The hourly predicted concentrations of imidacloprid and fipronil were accurate in both paddy water and 1 cm deep paddy soil. The coefficient of determination and Nash-Sutcliffe model efficiency were greater than 0.87 and 0.60 respectively. The 95th percentiles of the predicted concentrations of fipronil and imidacloprid indicated that the influence of input uncertainty was minor in paddy water but important in paddy soil. The pesticide deposition rate and the desorption rate from the root zone were identified to be the major contributors to the variation in the predicted concentrations in paddy water and soil. CONCLUSION: The PCPF-NB model was validated for predicting the fate and transport of NB-applied fipronil and imidacloprid using the BT and AS treatment methods. © 2015 Society of Chemical Industry.

Produção de óleo essencial de Melissa officinalis L. em diferentes épocas, sistemas de cultivo e adubações / Essential oil of Melissa officinalis L. at differents seasons, systems of planting and fertilizations

Os objetivos deste trabalho foram avaliar a biomassa, o rendimento e a composição de óleo essencial de Melissa officinalis L. submetida a diferentes épocas de plantio, sistemas de cultivo, e adubações. O delineamento experimental foi o de blocos casualizados (DBC), em esquema fatorial 2 x 2 x 2, sendo duas épocas de plantio (verão e inverno), dois sistemas de cultivo (estufa e campo), e dois tipos de adubação (mineral e orgânica). A colheita consistiu no corte de todas as plantas da parcela útil. Após a colheita, foi avaliada a massa fresca foliar, a altura de plantas, o comprimento e largura das folhas. A extração de óleo essencial foi realizada por hidrodestilação e a composição química foi analisada em cromatógrafo gasoso acoplado a espectrômetro de massas. Das substâncias encontradas, prevaleceram como constituintes majoritários os monoterpenos geranial e neral na colheita de verão, e geranial, neral e citronelal na colheita de inverno. As condições do ambiente protegido e do verão propiciaram melhor biomassa de melissa, maior rendimento de óleo essencial, e maior taxa do constituinte citral.

The objectives of this study were to evaluate the biomass, yield and composition of essential oil of Melissa officinalis L. under differents seasons, systems of planting and fertilizations. The experimental design was a randomized block design (RBD), in a factorial 2 x 2 x 2 with two seasons of harvest (summer and winter), two systems of planting (greenhouse and field) and two types of fertilizer (mineral and organic). The harvest consisted of cutting all plants of central line. After harvest, it were evaluated the leaf fresh weight, height of the plant, length and width of the leaves. The essential oil extraction was performed by hydrodistillation and the chemical composition was performed by gas chromatography coupled by mass spectrometry. The major constituents were geranial and neral in summer harvest and geranial, neral and citronellal in winter harvest. The conditions of the greenhouse and the summer presented the better biomass, higher yield of oil and higher rate of citral.