Screening Of Meloidogyne Hapla Nematicides For Tow Alpine Medicinal Plants

Aucklandia lappa Decne.is a genuine medicinal of Yunnan province,which is listed as one of the"Top 10 Yunnan Medicines".It has the effects of promoting qi and relieving pain,strengthening spleen and eliminating food.Gentiana crassicaulis Duthie ex Burk.is a plant of Gentianaceae,which has the effects of dispelling rheumatism,clearing heat and dampness,relieving arthralgia and relieving deficiency heat,so there is a large market demand.With the continuous expansion of planting area,the damage of Meloidogyne hapla to Aucklandia lappa and Gentiana crassicaulis is common,which seriously restricts the yield and quality of Aucklandia lappa and Gentiana crassicaulis.In this paper,the sensitivity of Meloidogyne hapla to 40%fluene sulfone EC,20%fosthiazate EW,5%abamectin EC,41.7%fluopyram SC,200 million spores/g Paecilomyces lilacinus powder,2.5 billion spores/g Verticillium dahliae microparticles and 10 billion spores/g Bacillus firmus wettable powder was determined,the nematicides with high efficiency against Meloidogyne hapla and safe nematicides for Aucklandia lappa and Gentiana crassicaulis seedlings,the effects of different doses of seven nematicides on the control of Meloidogyne hapla were evaluated by indoor pot experiment,and the feasibility of seven nematicides to control Meloidogyne hapla was verified by field experiment.The main results are as follows:（1）The effects of the nematicides on seeds germination and seedlings growth were preliminarily determined.It was found that the inhibitory effect of seven nematicides on the germination of Gentiana crassicaulis seeds was greater than that of Aucklandia lappa.Among them,fluoroene sulfone had the strongest inhibitory effect on the germination of Aucklandia lappa and Gentiana crassicaulis seeds,and the germination rates were 12.97%～20.67%and 4.67%～11.33%,respectively.The 400mg/L nematicides had no phytotoxicity symptoms to the seedlings.（2）The results of nematicides test showed that fluopyram had a good effect on the hatching inhibition of eggs and the second stage juveniles of Meloidogyne hapla after 24 h treatment.The egg hatching inhibition rates of abamectin,sulfone,fluopicolide and fosthiazate were between 21.47%～93.95%,which were higher than those of the three biological nematicides.Fluopyram and Paecilomyces lilacinus had strong killing activity against the second stage juveniles of Meloidogyne hapla,with LC₅₀of 0.885 mg/L and 2.610?10⁶ spores/m L^-1.（3）The preventive effect of the nematicides on the Meloidogyne hapla was studied under indoor pot conditions.It was found that the use of 400 mg/L abamectin to treat the seeds of Aucklandia lappa and 400 mg/L fluoroalkene sulfone to treat the seedlings of Aucklandia lappa had a better preventive effect on Meloidogyne hapla.The prevention effect was better,and the control effects were 62.87%and 31.43%,respectively,which were significantly higher than the other five nematicides.（4）The control effect of nematicides on Meloidogyne hapla of Aucklandia lappa was studied under indoor pot conditions.It was found that abamectin and Paecilomyces lilacinus had better control effect.Within the recommended dosage range of the nematicides,20 mg/kg abamectin and 8?10⁷ spores/kg/kg Paecilomyces lilacinus had better control effect,and the control effect was 46.67%,which was significantly higher than other treatments.（5）In the field experiment,fluopyram had the best effect on controlling Meloidogyne hapla.All of the 7 nematicides had control effect on Meloidogyne hapla within the recommended dosage range,among them,the effect of fluopyram was better,and the control effect of 25 ml/667m² was 36.82%.Followed by fosthiazate and Paecilomyces lilacinus,1000 ml/667m² fosthiazate and 15 kg/667m²Paecilomyces lilacinus control effect were 34.18%.