Assessment of microbial biocontrol agent (BCA) viability to mechanical and thermal stress by simulating spray application conditions.

BACKGROUND: In order to improve the biological control agent (BCA) efficacy, stress factors threatening the viability of microorganisms during spray application need to be determined. The effect of spray mixture temperature and exposure time on Trichoderma harzianum T 22 and Bacillus amyloliquefaciens QST713 viability were tested. Concurrently the combined effect of mechanical and thermal stress effect on BCA viability were tested at two initial spray mixture temperatures (14 and 25 °C) by simulating a spray application using airblast sprayers featured by different tank capacity and a spray liquid circuit (without and with hydraulic agitation system). To assess the BCA microorganism viability, spray mixture samples were collected at time intervals along trials and plated to count the colony forming units (CFU). RESULTS: The critical temperature threshold that inhibited BCA viability was 35 °C with 30 min of exposure. The sprayer type, the initial temperature of the spray mixture and the temperature increment during the trials significantly decreased the number of CFU recovered. When simulating a spray application, the spray mixture temperature increase rate was determined mainly by the residual amount of spray mixture in the tank. Even if the tank capacity does not substantially affect the final temperature reached by the spray mixture, the higher residual spray mixture in bigger tanks can expose the BCAs for a longer time to critical temperatures. CONCLUSIONS: Experimental trials allowed us to identify the effect of factors affecting the viability of tested BCAs, providing information about the actual chance to guarantee the biological efficacy of BCA treatments. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Dust drift during mechanical and pneumatic wheat sowing and insights into the physicochemical characteristics of the abraded dust.

BACKGROUND: During sowing, plant protection products (PPP)-laden dust particles can be abraded from coated seeds and emitted into the atmosphere. Drift of these particles is a very complex phenomenon and depends on many factors, including the physicochemical characteristics of the dust. Currently, the available data needed to obtain a better understanding of the phenomenon and to build a risk assessment tool remain very limited. In this study, new data on dust drift and on the physochemical characteristics of dust abraded from wheat seeds generated using a pneumatic and a mechanical seeder were obtained. These data will serve as input to optimize a much-needed computational fluid dynamics (CFD) model. RESULTS: The dust generated by the pneumatic seeder contained a greater volume of smaller particles (<150 µm) than the mechanical seeder dust, which contained a greater volume of larger particles (>1000 µm) than pneumatic seeder dust. Compared to the pneumatic seeder, the mechanical seeder showed lower drift values. With both seeders, the drift depositions decreased with increasing distance from the sowing area but no clear relationship between dust drift and wind speed could be found. CONCLUSION: The gathered physicochemical and drift data for wheat seed drilling extend the current dust drift database, and help to better understand the complex dust drift phenomenon. These data will serve as input to refine and validate a CFD dust drift model. Such a model will allow a better and quicker assessment of different scenarios (e.g. varying wind speeds and direction, treatment, drilling technique) at a lower cost than conducting more field trials. © 2023 Society of Chemical Industry.

Boom sprayer optimizations for bed-grown carrots at different growth stages based on spray distribution and droplet characteristics.

BACKGROUND: Pesticide losses and uneven spray distribution should be avoided as much as possible as they reduce the effectiveness of spraying and increase environmental contamination as well as costs. Within the H2020-project OPTIMA the goal is to develop a smart sprayer for bed-grown carrots, including optimizations such as air support and variable nozzle spacing. This paper focuses on selecting the most optimal nozzle types, spacing and height for spraying bed-grown crops, while taking into account different target zone widths depending on the growth stage, based on spray distribution and droplet characterization measurements. RESULTS: The results indicate that four bed spray configurations consisting of four nozzles per bed, i.e. XR8004/XR8004/XR8004/XR8004, AIUB8504/AI11004/AI11004/AIUB8504, AI8004/AI8004/AI8004/AI8004 and XR8002/XR8002/XR8002/XR8002, spraying at 300 kPa and recalculated to 12.0 km h-1 forward speed, are appropriate for spraying different target zone widths (ranging from 1.2 to 2.2 m) with high uniformity (CV < 12%) and minimal losses out of the target zone (<17%) when applied at the most appropriate nozzle spacing and height (varying from 0.35 to 0.65 m). Droplet characterization measurements showed that for the same nozzle size and spray pressure, air inclusion nozzles produced larger but slower droplets than standard flat-fan nozzles. Air support increased the droplet velocities but had only a very limited effect on droplet size. CONCLUSION: Laboratory spray distribution and droplet characterization measurements allowed selection of the most optimal nozzle type, spacing and height for bed spray applications in terms of reduced pesticide losses compared to conventional broadcast applications. © 2022 Society of Chemical Industry.

Characteristics of dust particles abraded from pesticide treated seeds: 1. Size distribution using different measuring techniques.

BACKGROUND: Particle size is one of the most important properties affecting the driftability and behaviour of dust particles abraded from pesticide dressed seeds during sowing. Three particle sizing techniques were used determine the particle size distribution of dust abraded from seeds from six different species. RESULTS: Important differences in dust particle size distribution between species were observed with the finest dust for rapeseed and the coarsest dust for barley. Wet laser diffraction and sonic sieving particle size results correlated well while micro-CT is able to deliver three-dimensional information and additional physical particle properties (shape, porosity). CONCLUSION: All particle sizing techniques have their (dis)advantages and none of them is able to perfectly describe the real size distribution of non-spherical particles. The particle size information gathered can be used in dust drift prediction models, risk assessment tools and will help to better understand the dust drift phenomenon. © 2017 Society of Chemical Industry.

Development and implementation of a laboratory spray device and rainfall simulator for retention research using small amounts of agroformulations.

BACKGROUND: Rainfall greatly affects the retention of foliar-applied agroformulations. Improving their resistance to wash-off is therefore of great importance in spray applications. When developing such formulations, small-scale laboratory assays are generally required. A set-up for retention studies using only small amounts of agroformulations (<0.5 L) was developed. The set-up consists of a spray device and a rainfall simulator. The effect of rain quantity (1, 3, 6 mm) on the spray retention of agroformulations was evaluated using this set-up. RESULTS: The data showed that uniform and repeatable spraying was achieved with the small-scale spray device (coefficient of variation 23.4%) on potato pot plants (Solanum tuberosum L.). Rain quantity significantly affected the spray retention. Approximately 40% of the initial deposition was lost after 1 mm of rain at an intensity of 25 mm h-1 . Additional losses decreased with increasing volumes of rain (65 and 80% loss after 3 and 6 mm of rain respectively). CONCLUSION: Future studies could implement the set-up to evaluate the effect of different rainfall characteristics and formulations on spray retention in order to improve the rainfastness of agroformulations. © 2016 Society of Chemical Industry.

Assessment of the abrasion potential of pesticide-treated seeds using the Heubach test.

During sowing of pesticide-treated seeds, pesticide-laden dust and abraded seed particles may be emitted to the environment, possibly leading to environmental contamination and posing health risks. In many countries there is currently no legislation concerning the acceptable amount of dust of treated seeds. This study aimed to gain insight in the abrasion potential of available pesticide-treated seeds and its associated factors. The abrasion potential of 45 seed samples of 7 different species (viz. sugar beet, oat, barley, wheat, spelt, pea, and maize) was determined using the Heubach test and amounts of dust were expressed as g 100 kgseeds-1, g 100,000 seeds-1, and g ha-1. The abrasion potential fell generally within the boundaries of maximum permissible values adopted by different countries. Species, seed treatment company, number of active ingredient (AIs) and combination of AIs had significant effects on the abrasion potential, whereas little or no effect of agitation and conservation was found. However, species were situated differently with respect to each other depending on the unit in which the abrasion potential was expressed. A standard unit that takes into account the species' seed rate is suggested to give the fairest assessment of dust drift risk and would allow international comparison.

Lameness Detection in Dairy Cows: Part 1. How to Distinguish between Non-Lame and Lame Cows Based on Differences in Locomotion or Behavior.

Due to its detrimental effect on cow welfare, health and production, lameness in dairy cows has received quite a lot of attention in the last few decades-not only in terms of prevention and treatment of lameness but also in terms of detection, as early treatment might decrease the number of severely lame cows in the herds as well as decrease the direct and indirect costs associated with lameness cases. Generally, lame cows are detected by the herdsman, hoof trimmer or veterinarian based on abnormal locomotion, abnormal behavior or the presence of hoof lesions during routine trimming. In the scientific literature, several guidelines are proposed to detect lame cows based on visual interpretation of the locomotion of individual cows (i.e., locomotion scoring systems). Researchers and the industry have focused on automating such observations to support the farmer in finding the lame cows in their herds, but until now, such automated systems have rarely been used in commercial herds. This review starts with the description of normal locomotion of cows in order to define 'abnormal' locomotion caused by lameness. Cow locomotion (gait and posture) and behavioral features that change when a cow becomes lame are described and linked to the existing visual scoring systems. In addition, the lack of information of normal cow gait and a clear description of 'abnormal' gait are discussed. Finally, the different set-ups used during locomotion scoring and their influence on the resulting locomotion scores are evaluated.

Lameness Detection in Dairy Cows: Part 2. Use of Sensors to Automatically Register Changes in Locomotion or Behavior.

Despite the research on opportunities to automatically measure lameness in cattle, lameness detection systems are not widely available commercially and are only used on a few dairy farms. However, farmers need to be aware of the lame cows in their herds in order treat them properly and in a timely fashion. Many papers have focused on the automated measurement of gait or behavioral cow characteristics related to lameness. In order for such automated measurements to be used in a detection system, algorithms to distinguish between non-lame and mildly or severely lame cows need to be developed and validated. Few studies have reached this latter stage of the development process. Also, comparison between the different approaches is impeded by the wide range of practical settings used to measure the gait or behavioral characteristic (e.g., measurements during normal farming routine or during experiments; cows guided or walking at their own speed) and by the different definitions of lame cows. In the majority of the publications, mildly lame cows are included in the non-lame cow group, which limits the possibility of also detecting early lameness cases. In this review, studies that used sensor technology to measure changes in gait or behavior of cows related to lameness are discussed together with practical considerations when conducting lameness research. In addition, other prerequisites for any lameness detection system on farms (e.g., need for early detection, real-time measurements) are discussed.

Thermal conditions during juvenile development affect adult dispersal in a spider.

Understanding the causes and consequences of dispersal is a prerequisite for the effective management of natural populations. Rather than treating dispersal as a fixed trait, it should be considered a plastic process that responds to both genetic and environmental conditions. Here, we consider how the ambient temperature experienced by juvenile Erigone atra, a spider inhabiting crop habitat, influences adult dispersal. This species exhibits 2 distinct forms of dispersal, ballooning (long distance) and rappelling (short distance). Using a half-sib design we raised individuals under 4 different temperature regimes and quantified the spiders' propensity to balloon and to rappel. Additionally, as an indicator of investment in settlement, we determined the size of the webs build by the spiders following dispersal. The optimal temperature regimes for reproduction and overall dispersal investment were 20 degrees C and 25 degrees C. Propensity to perform short-distance movements was lowest at 15 degrees C, whereas for long-distance dispersal it was lowest at 30 degrees C. Plasticity in dispersal was in the direction predicted on the basis of the risks associated with seasonal changes in habitat availability; long-distance ballooning occurred more frequently under cooler, spring-like conditions and short-distance rappelling under warmer, summer-like conditions. Based on these findings, we conclude that thermal conditions during development provide juvenile spiders with information about the environmental conditions they are likely to encounter as adults and that this information influences the spider's dispersal strategy. Climate change may result in suboptimal adult dispersal behavior, with potentially deleterious population level consequences.