Management of grape powdery mildew with an intelligent sprayer and sulfur

Wine grapes are an important agricultural commodity in the Pacific Northwest where grape powdery mildew (GPM) is one of the main disease problems. The efficacy of different sulfur concentrations and different output volumes from an air blast sprayer retrofitted with the Intelligent Spray System (ISS) were evaluated for the management of GPM. The ISS consists of a LiDAR sensor, Doppler speed sensor, embedded computer, flow controller, and individual pulse-width-modulation solenoid valves at each nozzle. GPM cluster severity ranged from 55% to 75% across all trials in the study when using the ISS at its default spray rate of 62.5 ml m-3 and micronized sulfur at 6 g L-1, which was significantly higher than all other fungicide treatments, but lower than non-treated controls. Similarly, leaf incidence values were highest on non-treated vines, followed by micronized sulfur at 6 g L-1 applied at 62.5 ml m-3 , with all other fungicide treatments being significantly lower in all trials. Using the ISS at the 62.5 ml m-3 rate and a rotation of locally systemic fungicides resulted in the lowest observed GPM leaf incidence, and average cluster severity of 11% in both 2019 and 2020, the lowest cluster severity of all fungicide treatments tested. GPM control using the ISS and micronized sulfur was equivalent to a constant-rate air blast treatment at 6 g L-1 when the spray rate of the ISS was increased to 125ml m-3, or if the concentration of sulfur was increased to 24 g L-1. In those cases, the amount of sulfur applied to vines was at or above the minimum label rate from bloom until the end of the season, or the entire season, respectively. This study has shown that sufficient disease control cannot always be expected when mixing pesticides at the same rate as would be used for a constant-rate sprayer in a variable rate sprayer, especially when using contact fungicides like sulfur . With appropriate adjustments, the variable-rate ISS can be a useful tool to reduce pesticide quantities, water required for mixing, and as a result labor, as fewer trips to refill for a given spray event are required.

The Relationship of Fear-Potentiated Startle and Polysomnography-Measured Sleep in Trauma-Exposed Men and Women with and without PTSD: Testing REM Sleep Effects and Exploring the Roles of an Integrative Measure of Sleep, PTSD Symptoms, and Biological Sex

Study Objectives Published research indicates that sleep is involved in emotional information processing. Using a fear-potentiated startle (FPS) and nap sleep protocol, we examined the relationship of emotional learning with REM sleep (REMS) in trauma-exposed participants. We also explored the roles of PTSD symptoms, biological sex, and an integrative measure of polysomnography-measured (PSG) sleep in the learning-sleep relationship. Methods After an adaptation nap, participants (N=46) completed 2 more visits (counterbalanced): a stress-condition visit, which included FPS conditioning procedures prior to a nap and assessment of learning retention and fear extinction training after the nap, and a control visit, which included a nap opportunity without stressful procedures. FPS conditioning included a “fear” visual stimulus paired with an air blast to the neck and a “safety” visual stimulus never paired with an air blast. Retention and extinction involved presentation of the visual stimuli without the air blast. Primary analyses examined the relationship between FPS responses pre- and post- sleep with stress-condition REMS duration, controlling for control-nap REMS duration. Results Higher safety learning predicted increased REMS and increased REMS predicted more rapid extinction learning. Similar relationships were observed with an integrative PSG sleep measure. They also showed unexpected effects of PTSD symptoms on learning and showed biological sex effects on learning-sleep relationships. Conclusions Findings support evidence of a relationship between adaptive emotional learning and REMS. They underscore the importance of examining sex effects in sleep-learning relationships. They introduce an integrative PSG sleep measure with potential relevance to studies of sleep and subjective and biological outcomes.

The Application of Quaternions to Strap-Down MEMS Sensor Data

We describe the mathematical transformations required to convert the data recorded using typical 6-axis microelectromechanical systems (MEMS) sensor packages (3-axis rate gyroscopes and 3-axis accelerometers) when attached to an object undergoing a short duration loading event, such as blast loading, where inertial data alone are sufficient to track the object motion. By using the quaternion description, the complex object rotations and displacements that typically occur are translated into the more convenient earth frame of reference. An illustrative example is presented where a large and heavy object was thrown by the action of a very strong air blast in a complex manner. The data conversion process yielded an accurate animation of the object’s subsequent motion.

Reducing the Nursery Pesticide Footprint with Laser-guided, Variable-rate Spray Application Technology

Nursery producers are challenged with growing a wide range of species with little to no detectable damage from insects or diseases. Growing plants that meet consumer demand for aesthetics has traditionally meant routine pesticide application using the most time-efficient method possible, an air-blast sprayer, despite its known poor pesticide application efficiency. New variable-rate spray technology allows growers to make more targeted applications and reduce off-target pesticide loss. In this study, a prototype laser-guided variable-rate sprayer was compared with a traditional air-blast sprayer. Pesticide volume, spray application characteristics, and the control of powdery mildew were evaluated over the course of two growing seasons. Spray application characteristics were assessed using water-sensitive cards (WSCs) and DepositScan software. This prototype sprayer reduced pesticide volume by an average of 54% across both years despite being tested against a low rate (<250 L⋅ha−1). In 2016, the conventional sprayer had more than double the deposit density on target WSCs among distal trees than the variable-rate sprayer; however, within proximal trees, there was no difference between the two sprayer types. In 2017, when the trees were larger, within both the distal and proximal trees, the conventional sprayer had greater deposit density on target WSCs than the variable-rate sprayer. In 2016, coverage on target WSCs was nearly 7-fold greater with the conventional treatment than with the variable-rate treatment. In 2017, when trees were larger, there was greater coverage on target WSCs in proximal trees (3.8%) compared with those in distal trees (1.0%) regardless of the sprayer type. This variable-rate spray technology provided acceptable control of powdery mildew severity on individual branches and whole trees and maintained the incidence of powdery mildew to levels comparable to that occurring among trees sprayed with a traditional air-blast sprayer. Therefore, the variable-rate spray technology has the potential to effectively control disease, dramatically reduce the pesticide footprint, and preserve natural resources such as ground and surface water, soil, and beneficial insects found within and around nurseries.