SURFOM ULV 8: Improving Drone Application efficiency by increasing actives deposition and droplet coverage

Contribute to the future of a sustainable agriculture and help to feed more than 10Bi people in 2050 is the challenge that drives Oxiteno’s commitment to develop solutions that enables the full potential of our customer’s formulations in the field. Therefore, Oxiteno has launched SURFOM ULV 8, an outstanding choice for Drone Applications. By increasing AI deposition and droplet coverage, SURFOM ULV 8 is a good tool to improve the performance of pesticides.

The use of drones for aerial applications is gaining space in the global Ag scenario leveraged by sustainability aspects and Agriculture 4.0. Aside from precise applications that requires less product to be applied and consequently less waste of products, the water usage at drone application can be significantly lower when compared to conventional methods. In addition to that, drones’ applications represent a safer method for farmers to work, besides of being a versatile tool that can be used in different crops in a varied of geography conditions.

To ensure the benefits mentioned, there are technical aspects that should be addressed considering drone’s application. Wrong dosages of pesticide may imply on increasing pest resistance, hence less productivity. Droplet size and formulation stability are key factors that might affect the performance of application, therefore choosing the right adjuvant is important to ensure that the right amount of pesticide is applied to the target area.

SURFOM ULV 8 is a blend of non-ionic surfactants that can reduce up to 50% of surface tension of the formulation, hence contributing to a better distribution of the AI in the surface. Another key aspect of its application is reduction of ″bouncing″ effect of droplets, ensuring that the pesticide stays at the leaf and reducing its losses. SURFOM ULV 8 has also presented a better spreading when compared to the benchmark’s tested, contributing to the AI penetration which decreases the waste of product applied through aerial application.

SURFOM ULV 8 has been tested in different crops in China by Oxiteno technical Team with a partner contribution and it has presented good results as following.

Performance tests

To quantify the parameters that could cause differences in the drone application it was evaluated physicochemical properties of SURFOM ULV 8 and two other Benchmarks. The technical data and its protocols were carried out by a partner within local Oxiteno Technical Team. Field trials were also performed to compare SURFOM ULV 8 against Benchmark#1, a tank mix adjuvant recommended for triazoles fungicides. Benchmark#2 is a blend of surfactants positioned as compatibilizer of pesticides mixtures.

SURFOM ULV 8 showed excellent performance in lab tests and field trials, proving to be a great tank mix adjuvant option for use in drone application.

Static Surface Tension - SST

An adjuvant with low SST will promote this characteristic to the spray solution containing the active ingredient. The smaller the SST, the better the spreading of solution, hence it’s possible to correlate it to a better distribution of the active ingredient. The graph bellow shows that SURFOM ULV 8 presented the lowest SST when compared to benchmarks 1 and 2.

Figure 1: Static Surface tension in function of adjuvant concentration.

Dynamic Surface Tension - DST

The DST in the first milliseconds, which is the time that occure droplet formation, is important because a low DST indicates that we will have small droplets, which will lead to high leaf coverage.

In general, the surface age is observed at 20 ms, to correlate with the bouncing performance. Smaller DST tends to have a larger and faster spreading which will prevent droplet bouncing.

Figure 2: Dynamic Surface Tension in function of surface age.

Wetting time

The SURFOM ULV 8 demonstrated low wetting time, even at low concentration. This property makes the leaf covered by the pesticide quickly avoiding loss of pesticide and might help improve the penetration of the active ingredient into the leaves.

Figures 3: Wetting time analysis using sinking canvas piece

Spreading behavior

At the spreading test into parafilm surface using different concentrations we observed that there is no big change in concentration greater than 0.4%.

Comparing the spray solution spreading behavior with different adjuvants into different surfaces (parafilm, cotton and rice leaf) we observed that SURFOM ULV 8 has very great spreading power and superior to benchmarks.

Spread on parafilm surface

Figure 4: Spread on parafilm surface for different concentration.

Spread on cotton leaf surface

Figure 5: Spread cotton leaf surface at 1% v/v

Spread on rice leaf surface

Figure 6: Spread on rice leaf surface at 1% v/v

Droplet rebound on rice leaf

We can see that in the spray solution containing SURFOM ULV 8 adjuvant, the spray droplet was not rebounded, as occurred with Benchmark#1 and Benchmark#2, enhancing the adhesion of spray solution on the rice leaf due to sticker property of SURFOM ULV 8.

Figure 7: Droplet rebound on rice leaf

Impact behavior of spray solution droplets on wheat leaves

Using a high-speed camera was possible to evaluate the effect of different adjuvants on the impact behavior of spray solution droplets on wheat leaves. It was tested a Tebuconazole 430 SC and 12.6% thiamethoxam + 9.3% Lambda Cyhalothrin ZC formulation: without adjuvant (1); with 1% of Benchmark#1 (2) and with 1% of SURFOM ULV 8 (3).

Figure 8: Impact behavior of spray solution droplets on wheat leaves.

Field Trial Results

Oxiteno & partner has also performed field trials in order to evaluate SURFOM ULV 8 performance at UAVs (unmanned aerial vehicles). The spray volume and the protocols are described below.

Table 1. Composition of spray solutions in different treatments. The spray solution containing only the two formulation products was defined as CK.

Field information: Jun county, Hebi City, Henan Province – 2021
Drone information: He-16, VP110 015, 6 nozzles, Spray swath (coverage)：4m, Fly hight ：1.5 m, Fly velocity：6m/s, spray pressure: 0.35MPa.

Deposition of spray droplets on water-sensitive papers using Drone application in wheat field

According to the results below it’s possible to see that the addition of 1% SURFOM ULV 8 (3) and Benchmark#1 (2) into the spray solution increased droplet deposition and leaf coverage, what might reduce droplet bouncing and improved pesticide deposition on leaves.

Figure 9: Droplet Coverage and Droplet deposition on wheat field.

Deposition of spray droplets on wheat leaves

According to the results below we observed that SURFOM ULV 8 increased the concentration of Tebuconazole on wheat. Even with 2/3 of the CK dose, the concentration of Tebuconazole was still higher than the formulation with CK alone. Showing that SURFOM ULV 8 reduce the bouncing droplet and enhance the spray solution adhesion on wheat leaf.

Figure 10: Tebuconazole deposition on wheat leaves.

Effectiveness of control of powdery mildew in wheat

Tebuconazole formulation with SURFOM ULV 8 has presented superior bioefficacy control of powdery mildew in wheat crop.

Figure 11: powdery mildew control after 14 days of treatment; Picture1: references [3]

Conclusion

The use of drones for aerial applications is an important tool to develop a more sustainable agriculture, however there are a lot of technical aspects to be considered for this application. Selecting the proper tank mix adjuvant is one of them.

SURFOM ULV 8 is a good tool to increase the coverage of spray on crop leaves. By reducing the surface tension, it contributes to decrease the active ingredient loss and allows a better absorption of it by the plant.

In addition to that, SURFOM ULV 8 has presented excellent performance in lab tests; presenting low dynamic surface tension, low wetting time, great spreading behavior in different surfaces, contributing to increase droplet deposition and leaf coverage, what might reduce droplet bouncing and improve pesticide deposition on leaves.

It also has presented good results at field trials performed in China for wheat, by increasing the amount of Tebuconazole deposition, hence the bioefficacy control in wheat powdery mildew.

References

[1] Internal Oxiteno report, 2022.
[2] Dorr GJ, Forster WA, Mayo LC, Mccue SW, Kempthorne DM, Hanan J et al., Spray retention on whole plants: modelling, simulations and experiments. Crop Prot 88:118–130, 2016.
[3] Source:https://eldersrural.com.au/news/powdery-mildew-control-in-wheat/; access in: 19/11/2022.