A Comprehensive Guide to Evaluating Pesticide Drift

Pesticide drift causing damage to non-target crops is one of the important reasons for pesticide Phytotoxicity. There have been multiple reports of litigation compensation due to pesticide damage caused by herbicide drift. A typical case is that two German agrochemical giants were ordered to pay compensation of US$265 million (around RMB 1.85 billion) because their produced Dicamba herbicide drift damaged peach trees owned by an American farmer. It is reported that this is the first lawsuit involving dicamba herbicide that has been heard by the court.

Herbicides prone to drift damage usually have smaller molecular weights, such as 2,4-D, MCPA, dicamba, etc. We often see risk warnings on the product descriptions of 2,4-D related products in the market, stating: "Pay attention to the wind direction during application to prevent the drift of the liquid to adjacent crops and avoid pesticide phytotoxicity." Products containing 2,4-D on the market mainly include 2,4-D isooctyl ester EC, 2,4-D dimethylammonium salt SL, and 2,4-D butyl ester EC. Are there any differences in the performance of anti-drift properties among different formulations and types of 2,4-D products? This requires us to conduct research to draw conclusions.

Pic 1. Pesticide Spray by using drone and large boom sprayer

The traditional method for testing pesticide drift volume involves the use of filter paper or polytetrafluoroethylene rope to set up collection points at different distances to collect the drifted pesticide droplets. Then, the dye in the droplets is eluted, and a UV-visible spectrophotometer is used to measure the absorbance of the eluate to determine the amount of droplet deposition. However, this method has several drawbacks, including operational difficulties, a long operation cycle, excessive human intervention, and high test risks.

Pic 2. Schematic Diagram of Traditional Drift Volume Testing Method

Sinvochem has developed a droplet drift testing system through close collaboration with domestic universities, research institutions, and equipment manufacturers. Combining with a wind tunnel system to simulate different environmental and climatic conditions, the system tests the number and volume of droplets drifted by the aqueous solution of different pesticides under different wind directions and speeds, spray nozzle models, spraying heights, and temperature and humidity conditions. It evaluates the drift differences of different pesticides, tests the anti-drift ability of pesticides when added with aerial spray adjuvants, and screens out highly efficient tank-mixed aerial spray adjuvants.

Pic 3. Wind tunnel system to test droplet drift volume

The droplet drift testing system uses the laser scattering method to measure the droplet drift volume, which has the advantages of accurate and real-time testing, easy operation, and compact instrument size.

We collected several types of 2,4-D isooctyl ester EC and 2,4-D dimethylammonium salt SL formulations available on the market and tested their drift volume using the droplet drift testing system. We selected a unified nozzle model, with a spraying pressure of 0.3Mpa and a crosswind speed of 1.5m/s, to measure the horizontally drift volume of the treatments over a distance of 2m. The test solution was configured according to the following dilution folds, and the test results are as follows:

Table 1. Drift Volume of 2,4-D Isooctyl Ester EC available on the market

The 2,4-D isooctyl ester EC formulations from market exhibit varying degrees of anti-drift ability. As seen in Table 1, Treatment E's formulation has a severe drift issue, with a drift volume 2-3 times higher than other products, and the number of drifted droplet is also greater. Among them, treatments B, C, and D have relatively less drift volume and higher safety.

Table 2. Drift Volume of 2,4-Ddimethylammonium SL available on the market

The 2,4-D dimethylammonium salt SL on the market also exhibits varying degrees of anti-drift capabilities, and there is a greater variance in drift volume among different formulations. Under the same testing conditions, the drift volume of 2,4-D dimethylammonium salt SL is significantly higher than that of 2,4-D isooctyl ester EC. As can be seen from Table 2, the drift volume of 2,4-D dimethylammonium salt SL products from 1 and 4 is relatively large, exceeding 1000 microliters per second, while the maximum drift volume of 2,4-D isooctyl ester EC does not exceed 100 microliters.

It can thus be concluded that the spray particle sizes vary among different formulations. Under the same spraying conditions, the spray particle size of emulsifiable concentrates is usually larger than that of aqueous solutions, resulting in a relatively smaller drift volume.

Anti-Drift Solution by Sinvochem:

The anti-drift adjuvant UNIFLY 001 is an effective additive that controls the distribution of spray droplets. After spraying from various nozzles, it enables uniform distribution of the spray droplets, effectively preventing droplet drift. Meanwhile, it possesses good anti-evaporation properties in high-temperature and dry environments, ensuring pesticide efficacy. Suitable for tank mixing in aerial application scenarios, this adjuvant can also be used in various mechanical spray boom sprayers, air-assisted sprayers, and other spray scenarios. Its main purpose is to address issues such as excessive evaporation of droplets during transfer, droplet drift along with wind, and improvement of pesticide adhesion and wettability during aerial or mechanical spraying at high dilution concentrations. When used in combination with pesticide packages for aerial applications, this adjuvant can enhance the stability of the diluted pesticide solution, effectively control the atomized droplet size within a reasonable distribution range, thereby reducing drift, promoting droplet sedimentation, resisting evaporation, and improving the affinity of pesticide to the crop.

Our company is equipped with droplet size analyzers and spray drift testers, which can simultaneously measure the droplet size and drift volume under different spraying conditions. We can provide customers with evaluations of pesticide drift, and jointly develop products with excellent anti-drift performance to better express the efficacy of pesticides!

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