Bioactivity And Control Efficiency Of Three Nematocides Mixture Against Meloidogyne Incognita In Tomato

Meloidogyne incognita is the main population causing tomato root-knot nematode disease.Due to the continuous and single planting of tomatoes in the protected field,the damage of root-knot nematodes has become more and more serious.At present,the control of tomato root-knot nematode disease mainly depends on chemical pesticides,which caused most nematicidal agents to face problems such as reduced control effects and pest resistance.In order to achieve efficient and safe management of root-knot nematodes,we mix fluopyram and abamectin to indoor bioassay test and screen out the optimal ratio of the two agents,and then use greenhouse pot test and field test to verify its control effects;At the same time,mix fluopyram and abamectin with different concentrations of cyclic dipeptides respectively,then verify the indirect effects of cyclic dipeptide on their control of root-knot nematodes.The main results are as follows:1.Indoor virulence measurementThe Meloidogyne incognita was used as the test object,fluopyram,abamectin and cyclic dipeptide were adopted to M.incognita in indoor bioassay test.The results at 48h showed that fluopyram and abamectin had higher virulence to root-knot nematode J2,and the LC₅₀ were2.53 mg/L and 1.62 mg/L respectively.The cyclic dipeptide had poor virulence to root-knot nematode J2,and its LC₅₀ value was 240.97 mg/L.In addition,according to the measurement results of single agent,the most effective compounding agent was selected by using fluopyram+abamectin at a ratio of active ingredients of 1:1,1:3,1:5,3:1,and 5:1.The results showed that the significant synergism were fluopyram+abamectin at the ratio of 1:1,1:3,and 1:5,and when the ratio is 1:5,the CTC value reached 268,and was the most obvious synergistic effect.2.Greenhouse pot testIn this test,Several compounding agents:fluopyram+abamectin were mixed at a ratio of 1:5?AB1,AB2,AB3?,and fluopyram was combined with 20 ng/mL,100 ng/mL,and 500ng/mL of cyclic dipeptide?A1,A2,A3?,Avermectin mixed with 20 ng/mL,100 ng/mL,and500 ng/mL of cyclic dipeptides?B1,B2,B3?,are used for the efficacy test.In the test,the growth of tomato,root vigor,the number of nematodes in the soil,and the root-knot index were investigated.The results showed that the two groups of fluopyram+abamectin 1:5?AB3?and fluopyram+cyclic dipeptide 100 ng/mL?A2?were more effective in preventing root-knot nematodes and were safe for plant growth.After the measurement of various indicators,we can find that the combination of fluopyram+abamectin 1:5?AB3?has more obvious effects than avermectin single agent?B?and fluopyram single agent?A?,and the combination of fluopyram+abamectin 1:5?AB2?has a synergistic effect compared with a single agent of Avermectin?B?.In addition,when the cyclic dipeptide was used at a concentration of 100 ng/mL,it had a synergistic effect on both single agents?A,B?.3.Field testThe treatment of each agent in the field efficacy test is the same as the pot test.in the test,the number of root-knot nematodes in rhizosphere soil during tomato growth and the root-knot index during tomato cleaning were investigated.The results,at 30 d and 60 d,showed that the application of fluopyram+abamectin 1:5?AB3?significantly decreased root-knot nematode population,and the control effect of nematode was 53.04%and 58.13%.At the same time,the root-knot index under this treatment is the lowest,and the control effect was 46.64%.In addition,fluopyram+cyclic dipeptide 500 ng/mL?A3?also showed good control effects.Comprehensively found that the cyclic dipeptides of 100 ng/mL and 500ng/mL had synergistic effects on fluopyram and abamectin,but the synergistic effects were not as obvious as those of the two treatment groups of fluopyram+abamectin 1:5?AB2,AB3?.