| Root rot is one of the main root diseases of Atractylodes macrocephala Koidz..The yield loss caused by this disease reached about 10% with the incidence of disease in severe fields of 90%, which had brought the severe yield loss, having been the restriction factor of the A. macrocephala Koidz.. In order to control root rot of A.macrocephala Koidz. better, the pathogens were isolated from the infected A.macrocephala Koidz., the pathogens were identified according to the pathogenicity,morphology and molecular biological. The biological characteristics of the pathogens were tested. The inhibitory effects of 6 fungicides against F. oxysporum were detected by the mycelium growth rate test method, the field control tests were conducted.Meanwhile, the effects of intercropping and different fertilizers on root rot of A.macrocephala Koidz. were studied. The results listed below.1. Identification of pathogens of root rot of A. macrocephala Koidz.According to the pathogenicity tests, 61 kind of pathogen strains were isolated from the infected A. macrocephala Koidz.. Based on the characters and classification system of Fusarium of C. Booth, the results showed that the diameter of the colony was 5.1 cm after cultured on PDA in 4 days under 25℃. The right side of colony was round. The hyphas looked like white wool. The reverse side represented dark purple.Cultured 10 days later, the size of microconidium was 11.4(7.4~16.3) μm × 4.2(3.3~5.0) μm,reniform or ovoid. Macroconidium was fusiform, 2~5 septum, mostly as 3 separate,size 22.1(16.3~29.9) μm × 4.7(2.1~7.7) μm. Chlamydospore was easy to produce,round. Conidiophores were long and in bottle shape. The homology with F.oxysporum was 100% based on the r DNA-ITS sequence analysis. Combined the identification of morphological and molecular, the 61 kind of pathogen strains were all F. oxysporum.2. Biological characteristics of F.oxysporumThe pathogen was cultured in different medium, temperature, illumination, p H,carbon source and nitrogen source. The results showed as follows: Czapek’s medium and PDA were suitable for growth and sporulation of F.oxysporum; The range of temperature for growth and sporulation of F. oxysporum was 10~33℃, and theoptimum was 28℃. Full light was the best condition for growth and consistent darkness was the best condition for sporulation; The pathogen could grow from p H4 to p H12,p H7 was the best; The best carbon source for growth and sporulation were glucose and sucrose; The best nitrogen source for growth was sodium nitrate and potassium nitrate was the best nitrogen source for sporulation. The lethal temperature of conidia was58℃,10 min.3. Control of root rot of A. macrocephala Koidz.(1)Chemical control. With mycelium growth rate test method, six fungicides to F.oxysporum had inhibiton effects, indicating that the EC50 values of 80% Carbendazim WP, 15% Carbendazim + 15% Thiram WP, 4% Metalaxyl-M + 64% Mancozeb WP,8% Hymexazol + 56% Mancozeb WP, 70% Fenaminosulf WP, 30% Hymexazol SL were 1.0294 μg/m L, 5.2456 μg/m L, 55.2541 μg/m L, 73.4879 μg/m L, 160.3929 μg/m L and 306.3610 μg/m L, respectively, suggesting that 80% Carbendazim WP was the best.The correlation coefficients for the six fungicides were all above 0.95, indicating that mass concentration had high correlation with inhibition. The field control effect of 80%Carbendazim WP was the best, the control effect was 84.21%.The worst field control effect was 4% Metalaxyl-M + 64% Mancozeb WP with the control effect of 43.75%.(2)Agricultural control. The results of intercropping showed that A. macrocephala Koidz. intercropped with maize could decrease the occurrence of root rot. The control effects in different periods were 58.48%, 67.13%, 64.86%. The control effects of intercropping of soybean and A. macrocephala Koidz. in different periods were-0.74%,48.96%, 43.18%.The control effects of intercropping of garlic and A. macrocephala Koidz. in different periods were 32.11%, 40.49%, 34.09%.The results of different fertilization showed that the bacterial fertilizer I with control effect of 69.85% was the best. The bacterial fertilizer II with the control effect was 64.02%. |
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