Characteristics of plant-derived spray additives and their control effect on citrus red spider

In order to explore the effect of plant-derived spray additives in chemical control of reducing the amount and increasing the efficiency, the physical properties of three plant-derived spray additives (plant-derived glycerides, photosynthetic high-lipid membrane and Jukang high-lipid membrane) and mineral oil and their respective mixture with spirodiclofen were compared, and the field control effect of the plant-derived spray additives with the best physical properties and mineral oil against Panonychus citri (McGregor) were evaluated. The results showed that all of the four additives could significantly reduce the contact angle and improve the solid surface energy and adhesion properties of the spirodiclofen solution on citrus leaves. And the physical properties of the solution improved by plant-derived glycerides and photosynthetic high-lipid films were significantly better than those of mineral oil, especially the plant-derived glycerides, where the contact angle was reduced by 41.29°, the solid surface energy increased by 19.82 MJ/m², and the adhesion properties increased by 49.2 J/m². Jukang high-lipid membrane was better than mineral oil in terms of reducing the contact angle of chemical liquid. The recommended concentration (300 X) as additives of plant-derived glycerides and mineral oil were mixed with the reduction of 50% of recommended concentration of spirodiclofen against citrus red spider, respectively, and there was no significant difference in the control effect within 15 days, indicating that the two additives not only increased the control effect of spirodiclofen with reduced dosage, but also it could achieve the same effect with a 50% reduction in usage. However, two additives were applied separately to control citrus red spider, the control effect of 15-day of plant-derived glycerides was 63.2%, which was much higher than that of mineral oil. In summary, the three plant-derived spray additives were superior to mineral oil in improving the physical properties of spirodiclofen, and plant-derived glycerides outperformed the other two plant-derived additives, besides and the use of plant-derived glyceride alone also had a better control effect on citrus red spider. The results of this study provided a reference for the reducing the amount and increasing the efficiency of chemical control.