Coffee production and marketing is one of the main global commercial activities, but crop yields depend on several factors, among which plant health. The objective of this study was to evaluate the efficiency of spray droplet deposition in coffee crops grown in a mountain region, associated to the efficacy of the control of fungal diseases. The application efficiency, using an unmanned aerial vehicle (UAV), and the efficacy of the products applied were tested. Water-sensitive paper tags were used to analyze the application efficiency; agronomic efficiency, vegetative vigor, yield, and physiological parameters were used to determine the fungicide efficacy. Droplet coverage in the upper canopy layer using a pneumatic sprayer (28.70%) was 4.11-fold higher than that found in the same layer for application using a UAV (6.98%) at the rate of 15 L ha⁻¹. The highest droplet depositions by using a UAV were found for the rate of 15 L ha⁻¹: 1.60, 1.04, and 0.43 µL cm⁻² in the upper, middle, and lower layers, respectively; the deposition in the upper layer with application using a pneumatic sprayer was 42.67 µL cm⁻², and therefore, a 26.7-fold higher deposition. The results denote that the control of fungal diseases through fungicide applications using a UAV is efficient for mountain coffee crops.

The use of unmanned aerial vehicles (UAVs) in the agricultural and forestry sectors has constantly evolved due to its great versatility and applicability in the field. In this sense, this study provided a statistical overview of studies on the use of UAVs in agricultural and forestry through a bibliometric and scientometric analysis. For that, a research was carried out on the Scopus platform using the terms UAV, UAS, drone, and RPA, together with “agricult*” or “forest* or livestock”. Only manuscripts published in English and from January 2000 to December 2020 were selected. The VOSviewer software was used for the analyses. The USA and China were responsible for more than 38% of the publications worldwide. Furthermore, about 50% of the countries in the world showed some scientific record of the use of UAVs in agricultural and forestry studies. The term UAS was more used until 2016, while UAV was more mentioned between 2017 and 2018. Conversely, drone was more endorsed from 2019. The constant increase in scientific production reported in the research and the evolution of the co-occurrence of keywords corroborated two ideas: i) the use of UAVs is still undergoing transformations and is directly related to the advancement of technology included in these equipments; and ii) studies are still not enough to explore all the applicability of the UAVs in agriculture, livestock and forestry.

Available information on physical compatibility and stability of pesticide mixtures is scarce and often divergent. This knowledge is of fundamental importance in the success of pest, disease, and weed control programs. Compatibility and stability of two glyphosate formulations (WG and SL) in a mixture with fluazinam + deltamethrin + trifloxystrobin/cyproconazole at four diluted water concentrations and different times were evaluated under laboratory conditions. The evaluations were performed at the following time intervals: immediately after mixing and 1, 5, 10, 30, 120, 900, and 1,440 minutes after the mixing of pesticides. Scores were assigned on a scale ranging from 1 to 5, where 1 meant immediate separation of compounds and 5 the perfect mixture stability up to 30 minutes. The data were submitted to descriptive statistics and presented in tables. Mixture stability differed in glyphosate formulations and their concentrations due to the used spray solution volume. Distinct mixtures between glyphosate (SL) and deltamethrin, as well as between glyphosate (WG) and deltamethrin, were physically compatible when stirred again even after 24 hours at rest. The mixture containing glyphosate (SL), deltamethrin, and fluazinam and trifloxystrobin/ cyproconazole was incompatible at a volume of 30 L ha-1.

Optical sensors are useful tools for rapid and periodic assessment of plant nutritional status. However, the utility and potential of these sensors may be reduced if their readings change throughout the day. Therefore, this study aimed to assess the effects of time of day on measurements of the SPAD-502 chlorophyll meter and the GreenSeeker throughout the bean crop cycle. The treatments consisted of time of day for sensor measurements (8:00, 12:00, and 16:00 h) throughout six dates over the crop cycle. The results showed that measurements from the SPAD-502 and the GreenSeeker significantly changed according to time of day. The SPAD index at 16:00 h showed the lowest coefficient of variation (CV, 2.5%) and was on average, 3.05 ± 0.43, and 1.12 ± 0.25 SPAD units higher when compared to readings obtained at 8:00 and 12:00 h. Differently, the NDVI from the GreenSeeker showed the lowest CV (4.34%) at 8:00 h and was, on average, 0.06 ± 0.028 and 0.03 ± 0.01 units higher than measurements taken at 16:00 h and 12:00 h, respectively. Furthermore, the different times of sensor measurements present variations in air temperature and solar radiation, which directly influence the leaf water content and paraheliotropic movements. Thus, the indices from both sensors tend to show a high variability during different times of the day. Therefore, it is essential to create a consistent sampling protocol to reduce the variability of sensor measurements during the crop cycle.

The no-tillage system is considered an important tool for sustainable production. In this system, the burndown of brachiaria is usually performed with the application of systemic herbicides, such as glyphosate. As a result of environmental conditions (temperature, relative humidity and winds), the timing of spraying can directly interfere in the control efficiency. Therefore, the objective was to study different times of application of glyphosate in the control efficiency of Urochloa brizantha cv. Marandu. The glyphosate was applied in the morning, afternoon and evening, at doses of 0; 360; 720; 1080; 1440 and 2160 g a.e. ha-1. To analyse the efficiency of U. brizantha burndown, the phytotoxicity was evaluated at 21 days after application. At 42 after application a mowing was done and 90 days after mowing, the dry matter accumulation and the Leaf Area Index of regrowth were determined. The best control results of Urochloa brizantha cv. Marandu were obtained in the applications of glyphosate during the morning and afternoon. Evening applications of glyphosate should be avoided.