Security Agents Screening For Controlling Crown Rot And White Grub On Peanut By Seed Dressing

Crown rot is a common disease of peanut in agricultural production, which is caused bythe infection of Aspergillus niger v. Tiegh. Root-feeding white grubs (Larva Holotrichiae) area major global pest of diverse agricultural crops, and they are the most damaging group of soilinsects in most areas. Two pests have occurred seriously in peanut-producing areas inShandong Province, and efficient control measures should be studied. Highly active pesticidesabout treatment of peanut crown rot and grubs were screened through indoor prevention inthis study, and then they were mixed by seed dressing. In order to complement the absence offungicides and establish the reasonable and efficient application techniques in controllingpeanut crown rot, security evaluation and inoculated control efficiency of the mixedfungicides were preliminary determined in the greenhouse and then applied to the field tofurther confirm the control efficacy.Toxicity of different fungicides to A. niger that causes peanut crown rot was tested withthe mycelium growth rate and spore germination methods. Prochloraz, tebuconazole,kresoxim-methyl and carbendazim+thiram (1:1) were selected as high active fungicides.Toxicitiy of7insecticides to Holotrichia parallela and white grub were determined byinsect-dipping test to select effective insecticides. Chlorpyrifos and phoxim had relativelystable results, and have been registered to prevent grubs on peanut.Four fungicides were evaluated on peanut emergence by seed dressing in greenhouse.There was also no injury both in seed germination and seedling stage with tebuconazole, butthe emergence time was delayed compared with the control. There was no injury amongcarbendazim+thiram, prochloraz and kresoxim-methyl both in seed germination and seedlingstage, and the plant fresh weight, emergence time and seedling emergence was no differencewith control. Compared with the use of fungicides alone to deal with peanut, there was nodifference in the rate of emergence, emergence time and plant fresh weight by usingchlorpyrifos mixed with fungicides. Pot experiment in greenhouse also showed that thedisease incidence was97.50%and92.50%respectively after inoculation in sowing time androsette stage. Disease index was decreased significantly after treated with four fungicides, andthe control effects were close or above90%. Field experiment indicated that tebuconazole mixed with chlorpyrifos had the highesteffect in sowing time, and the control effect of chlorpyrifos to the white grub was ranged from47.74%to62.13%. Therefore, tebuconazole+chlorpyrifos was recommended against peanutcrown rot and grubs by seed dressing in sowing time, and then chlorpyrifos was used alone byfilling pier in the rosette stage to improve peanut production.