| Abstract: In order to prevent and control the damage of thrips on test-tube seedlings of potato and reduce the pollution rate caused by thrips, 'Shishu No.1' was used as the experimental material. Different concentrations of imidacloprid or thiamethoxam were added to MS medium to study the control effects of different pesticides on thrips
and the impact on the growth and development of test-tube seedlings. The results showed that in the control experiment of thrips, adding 70% imidacloprid water dispersible granule and 25% thiamethoxam water dispersible granule to MS medium could effectively reduce the root length and plant height of tes-tube seedlings. B1 treatment (2 000 times solution of 25% thiamethoxam water dispersible granule) showed the most significant inhibition on the growth of testtube seedlings. 10 000-20 000 times solutions of 70% imidacloprid water dispersible granule and 2 000-4 000 times solutions of 25% thiamethoxam water dispersible granule could effectively control thrips and reduced the contamination rate of test-tube seedlings. Among them, A1 treatment (10 000 times solution of 70% imidacloprid water dispersible granule), B1 treatment (2 000 times solution of 25% thiamethoxam water dispersible granule), and B2treatment (3 000 times solution of 25% thiamethoxam water dispersible granule) all had a contamination rate of 0.00%
in test-tube seedlings, indicating good control effect on thrips. In the experiment of releasing pesticide, the root length, plant height and internode spacing of C3 treatment were significantly higher than those of C1 treatment, and there were no significant differences between them and the control. The root length and plant height of D3 treatment were significantly higher than those of D1 treatment, and there were no significant differences between them and the control. This indicated that after 3 rounds of propagation in the medicated medium, using the non medicated medium for 2 rounds of propagation could quickly relieve the inhibitory effect of insecticides on growth, achieving the same growth status as normal plants. Therefore, 70% imidacloprid water dispersible granule at a concentration of 10 000 times solution and 25% thiamethoxam water dispersible granules at a concentration of 2 000 times solution could both prevent and control thrips in test-tube seedlings, and the growth inhibition effect of the pesticide could be quickly relieved after 2 rounds of propagation in a non-pesticide medium. |