STUDY OF THE EFFECT OF TWO SURFACTANTS ON SPRAY RETENTION BY BARLEY LEAVES

Surfactants are nowadays very useful additives to improve the effectiveness of phytosanitary treatments. They contribute to change the types of impact and thus the amount of spray retained by the leaves of the treated plant. We performed tests of retention on whole barley plants on BBCH 12 stage and small pieces of barley leaves at the same stage of growth. Spraying was done in three ways: water without surfactant, water with Break-Thru S240 and water with Li700. The three slurries of fluorescein contained in an amount of 0.2 g / l. Fluorescein retained by the leaves in both cases is then measured by a spectrofluoremeter. The retention tests on whole plants show that it is tripled by the first surfactant and doubled by the second. By cons on small pieces of barley leaves, the amount was increased by the use of surfactants but not to the same scale. This study concluded that the use of surfactants in spray pesticides may increase the amount of retention as a function of leaf area and the surfactant used

UAV spraying on citrus crop: impact of tank-mix adjuvant on the contact angle and droplet distribution

Adding tank-mix adjuvants into the spray mixture is a common practice to improve droplet distribution for field crops (e.g., rice, wheat, corn, etc.) when using Unmanned Aerial Vehicle (UAV) sprayers. However, the effectiveness of tank-mix adjuvant for UAV spraying in orchard crops is still an open problem, considering their special canopy structure and leaf features. This study aims to evaluate the effects of a typical tank-mix adjuvant concentrations (i.e., Nong Jian Fei (NJF)) on Contact Angle (CA) and droplet distribution in the citrus tree canopy. Three commonly used parameters, namely dynamic CA, droplet coverage, and Volume Median Diameter (VMD), are adopted for performance evaluation. The dynamic CAs on the adaxial surface of citrus leaves, for water-only and NJF-presence sprays, respectively, are measured with five concentration levels, where three replications are performed for each concentration. The sprays with 0.5‰ NJF are adopted in the field experiment for evaluating droplet distributions, where Water Sensitive Papers (WSPs) are used as collectors. Two multi-rotor UAVs (DJI T20 and T30) which consist of different sizes of pesticide tanks and rotor diameters are used as the spraying platforms. Both water-only and NJF-presence treatments are conducted for the two UAVs, respectively. The results of the CA experiment show that NJF addition can significantly reduce the CAs of the sprays. The sprays with 0.5‰ NJF obtain the lowest CA within the observing time, suggesting a better spread ability on solid surface (e.g., WSPs or/and leaves). With respect to the effects of NJF addition on individual UAVs, the field trial results indicate that NJF addition can remarkably increase both the droplet coverage and VMD at three canopy layers, except for T30 droplet coverage of the inside and bottom layers. Comparing the difference of droplet coverage between two UAVs, while significant difference is found in the same layer before NJF addition, there is no notable difference appearing in the outside and bottom layers after NJF addition. The difference of VMD in the same layer between two UAVs is not affected by NJF addition except for the bottom layer. These results imply that the differences of droplet coverage among different UAVs might be mitigated, thus the droplet distribution of some UAVs could be improved by adding a tank-mix adjuvant into the sprays. This hypothesis is verified by investigating the droplet penetration and the correlation coefficient (CC) of droplet coverage and VMD. After NJF addition, the total percentage of T20 droplet coverage in the bottom and inside layers is increased by 5%. For both UAVs, the CCs indicate that both droplet coverage and VMD increase at the same time in most cases after NJF addition. In conclusion, the addition of a tank-mix adjuvant with the ability to reduce CA of the sprays, can effectively improve droplet distribution using UAV spraying in the citrus canopy by increasing droplet coverage and VMD

Developmental wettability changes of soybean (Glycine max L) leaves and their impact on agrochemical behaviour

[no abstract

Umweltverhalten von Pflanzenschutzmitteln (Poster)

197 - Steindl, A.; Schroer, S. Risikobewertung von Nanofasern zum Einsatz als Pheromon-Dispenser198 - Hunsche, M.; Alexeenko, A.; Noga, G. Deposit characteristics, retention, and rainfastness of selected copper salts as influenced by tank-mix adjuvants199 - Schoenmuth, B.; Schenke, D.; Scharnhorst, T.; Büttner, C.; Pestemer, W. Ein zuverlässiges Transpirationstestsystem zur Phytotoxizitätstestung von Xenobiotika200 - Bischoff, G. Chemische Bienenuntersuchung – Details des neuen Verfahrens und ausgewählte Ergebnisse seit 2008201 - Jacobs, A.; Bischoff, G. Rückstandsverhalten und Lagerstabilität von Clothianidin und Pymethrozin 202 - Joachimsmeier, I.; Schenke, D.; Heimbach, U.; Pistorius, J. Rückstände von Clothianidin in Guttationstropfen von Mais nach Saatgutbehandlung bzw. Granulatanwendung203 - Joachimsmeier, I.; Heimbach, U.; Schenke, D.; Pistorius, J. Rückstände verschiedener Neonicotinoide in Guttationstropfen von Winterraps im Feldversuch204 - Bless, H.-G.; Bode, R. Die Dissipation von Wirkstoffen nach verschiedenen Pflanzenschutzmittelanwendungen im Feld zu Möhren und Weißkohl205 - Felgentreu, D.; Bischoff, G. Untersuchungen zum mikrobiellen Abbau von Pflanzenschutzmittel-Restbrühen nach 5-jähriger Nutzung von Biobeds206 - Pucelik-Günther, P.; Corsten, K.; Fischer, R. Metaboliten von Pflanzenschutzmittelwirkstoffen im Grundwasser – potentielle Versickerungsneigung und Monitoringergebnisse207 - Golla, B.; Klein, M.; Krumpe, J. GeoRisk: Modell und Parameter für eine georeferenzierte probabilistische Abschätzung der abdriftbedingten Pflanzenschutzmitteleinträge in Oberflächengewässer in Raumkulturen208 - Schenke, D.; Knutzen, F.; Jäckel, B.; Doobe, G.; Hilfert, G. Aufnahme von Dimethoat in Blätter von Spitzahorn, Linde und Kastanie nach Stammbehandlung mit Baumpflaster

Dicamba tank mixtures and formulations and their effects on sensitive crops during cleanout procedures

The introduction of dicamba-tolerant (DT) soybeans (Glycine max L. Merr) and cotton (Gossypium hirsutum L) in 2017 provided an additional tool for herbicide resistant weeds management. In the subsequent years, off-target movement of dicamba allegedly caused damage to sensitive crops and vegetation. Possible causes of off-target movement include tank contamination, physical drift, and volatility. Additional products, such as herbicides to control grass, are often added to tank with dicamba, which is used to control broadleaf weeds, to increase the spectrum of control and application efficiency. Dicamba products registered for DT crops require the use of drift reducing agents to mitigate unintended effects to adjacent crops. Sprayers are complex machines with valves, hoses, tanks, and nozzles that can retain herbicide residues and cause symptomology and/or injury to crops if proper cleanout procedures are not performed. Recommended cleanout procedures can be found in dicamba product labels, but there is no information available reporting the effect of tank mixtures or different dicamba formulations on retention of residues. The objective of this research was to: 1) evaluate the dicamba retention of potential tank mixtures with dicamba and drift reducing adjuvants, clethodim as well as tank-cleaning agents on non-DT soybeans, 2) evaluate the cleanout procedures of commonly used dicamba products, on non-DT soybean, and 3) investigate how the rinsate following cleanout procedures of dicamba mixtures affect such as soybean, cotton, tomatoes (Lycopersicon esculentum) and peanuts (Arachis hypogaea L.). Advisor: Christopher Procto