Studies On Occurrence And Control Of Southern Blight Of Atractylodes Macrocephala Koidzz

Atractylodes macrocephala Koidzz is a kind of perennial conpositae plants. It is a very important and valuable chinese medicine. However,the southern blight restricts seriously its growth and development. To control this disease,peasants use rotation and quintozone treatment. But it is not controlled well and maintains a disease and damage incidence of 5%-10%(the highest is beyond 25%).The research explore the regularity of the disease in climate,culture,variety and so on. Also it studies on IMP of this disease in fungicides,antagonists,soil-covered measures and basic fertilizers. The research has discovered:1. From the disease plants and sclerotia,14 strains of Trichodertna viride are isolated. They all show antagonism and can make sclerotia rotten in vitro and control southern blight in pot-grown tests. The highest rot incidenc is T4 and T3(87.5%,86.7%,respectively),and the lowest is Ti(20%). The control effects of T2 and T7 are all 70%,TI is 40%,the others are all 100%.2. High temperature is the most important climatic condition. There is a disease peak from late June to early September,because the average temperature of 10 days is higher than 26X?. Rainfall is an important factor as well.3. The disease incidence is different in different previous crops. Rice and corn with lower incidence are better previous crop than sweat potato,but the latter is better than peanut.4. The growth period cannot influence on this disease.5. The soil and irrigation conditions influence on this disease. The incidence is 3.0% in red soil sloping fields,but 5.5% and 14. 5% in water-discharged well and badly rice fields beside rever,respectively.6. The variety with plane flower head,large leaf and low stem,has more strong resistance to this disease than that variety having peakyflower head,little leaf and tall stem.7. Hymexazo] and carbendazim show strong inhibition to mycelia of Sclerotium rolfsii in vitro (EC50=6. 03mg/l,7. 08mg/l,respectively). But validamycin A is hardly effective (EC50=46. 77mg/l) . The complex of hymexazol and carbendazim or hymexazol and validamycin A do not show synergistic action (co-toxicity coefficient CTC=93.33,73.79,respectively).8. The trial results of field plot are similar to in vitro. Hymexazol and carbendazim are more effective apparently than validamycin A (control effect is 98. 81%,92.48%,26. 24% respectively). The complex of hymexazol and carbendazim or hymexazol and carbendazim has an effect of 93.67% or 54. 04% respectively.9. The disease can be controlled by soil-covered treatments after grown before seeding. While the covering material is leaves and stems of Dicranopieris dichoioma,the control,effect is 55.63%. Straw,new-soil and old-soil are 42. 5%,4. 94% and 1.28%,respectively.10. The basic fertilizers tests show that cattle dejecta have higher disease incidence(8. 17%) than human beings and pig dejecta,ashes and checks (3. 25%,3. 17%,2. 75%and 2. 75%,rspectively). Meanwhile,the fields investigation results indicated that human beings and pig dejecta are better than cattle dejecta as well (disease incidence=3. 5%,4.0%,17.0%,respectively).