Identification, Biological Characteristics And Control Of Root Rot On Atractylodes Macrocephala

Atractylodes macrocephala Koidz, perennial double cotyledon herbage, its dry rhizome named A. macrocephalae is Chinese traditional medicine. Zhejiang is the authentic region which has a long history of cultivation. Sichuan and Chongqing has acultivated for many years, too.Root rot diseases on A. macrocephala infected by imperfect fungi is one of the important diseases. From2010to2011, the yield loss caused by this disease in Baoxing, Sichuan reached about30%with the incidence of disease in severe fields of90%, which had brought the severe yield loss, having been the restriction factor of the atractylodes macrocephala production. This research is about the symptom, pathogen identification, biological characteristic and technique of integrated control of Root rot diseases on A. macrocephala,The results listed below.1. The symptoms of root rot diseases on Atractylodes macrocephalaRoot rot diseases on atractylodes macrocephala koidz is one kind of soil borne disease, which can occur during the whole child-bearing period.Early onset, a few rootlet and fibrous root become brown, wizened and rot. Then the main root is affected. Having been attacked, the section of the main root produces brown spots. Then the root and the stem become brown following the scab, making the whole vascular bundle system brown. At first, overground part is nomal, Then the ability to absorb water and nutrients weakens as the rot becomes heavier. Leaves on the upper apex wilt firstly because of the poor nutrients supply of the overground part especially before or after the noon of the fine day with strong sunshing and transpiration. But they can recover at night. As the disease becomes heavy, the leaves colour turns yellow from green gradually. The leaves turn small. The wilting can not recover at night. At last, the leaves dried-up from the top to the bottom till the death of the whole plant. The root and stem shrink or rot with the colour of yellow, representing dry rot or scald with white hypha. 2. Separation and culture character of pathogen of root rot disease on Atractylodes macrocephalaThe organization was separated and purified to obtain the pathogen of Atractylodes macrocephala root rot. Macroconidia was fusiform or cylindrical, slightly curved ends acuminate, base rostrate, spore heel conspicuous or not,3～5septum, mostly as3separate, size (3.7～5.2) μm×(16.7～43) μm. aerial mycelium. Long cylindrical single bottle stalks grew from sporogenous cells in the aerial hyphae. And the size of miniature conidium was3.9-13.8μm, oval or ovate. Pure isolations of the pathogen were obtained through organization separation. Morphological characteristic of the isolations on the PDA were almost the same.White and light gray and ink hyphas occur after2days. Sporalation began after3-4days.The hyphas with septas looked like cotton fibre. The right side of colony had concentric ring rot, while the reverse side represent light purple or saffron yellow.3. Inoculation and identification the pathogenof root rot disease on Atractylodes macrocephalaUnder the room temperature, the stabed roots were immersed in the suspensoid of the conidiospore.All plants were affected15days after inoculation with the same symptom as the fields. CK were not affected. The same pathogens were obtained through the routine separation in the affected parts, thus proving that the isolations were the pathogen of the root rot disease on atractylodes macrocephala koidz.This pathogen was identified as Fusarium lateritium according to the culture character,morphological characteristic rDNA-ITS and 《Plant pathogenic mycology》 written by Zhang Zhongyi and classification system of fusarium of Booth.The root rot disease on A. macrocephala caused by F. lateritium was first reported worldwide。4. The biology characteristics of F. lateritiumThis research ascertained the influence on the hypha growth, Sporulation and the conidiospore germination of the pathogen from the culture medium, temperature, nitrogen resource,carbon resource, pH and illumination. The results illustrated that the best culture medium for hypha growth and Sporulation was PSA with the colony diameter of4.23cm and the spores amount of34.14×107per petri dish and the worst culture medium for growth was starch culture-medium and for sporulation was WA; The optimum temperature for hypha growth and Sporulation ranged from10℃to30℃with the best of25℃.Temperature below5℃or upon35℃repressed the Sporulation and conidiospore germination even causing the malformation of the spore; The best carbon resource for growth were glucose and sucrose, for sporalation was sucrose and the worst for sporalation was amylum; The best nitrogen resource for growth and sporalation was nitrate while the worse of beef extract, the worst for growth was ammonium sulfate and the worst for sporalation was urea; The optimum pH for growth ranged from5to9with the best of7.5.The pH higher or lower caused bad effects; The fluorescence was the best illumination for growth sporalation.The best temperature for germination was28℃with germination rate of28℃.The best humidity was100%.The best pH was7.5.The spore did not germinate on the condition of pH upon9.The killing temperature of conidiospore was50℃。5. Screening of the pepticide and biocontrol agents8pepticides were used including Root rot Ling、mancozeb、chlorothalonil、 thiophanate methy、captan、Fuhuol、the four enzyme and the Victoria Street. The results showed that mancozeb and thiophanate methyl had good effect on hypha growth and sporalation suppression, reaching very significant。Hypha could hardly grow in the1000time liquids. It had the lowest sporalation amount。The suppression to the pathogen of captan and Fuhuol reached significant too. But the effect was worse than the former two. Chlorothalonil had the lowest effect, having noeffect on pathogen. Thiophanate methyl and Fuhuol had the best effect of conidiospore germination suppression with the rate of100%。Mancozeb、captan and Victoria Street had a worse effect with the rate of92.05%、88.28%and80.30%. Root rot Ling and chlorothalonil had the worst effect with the rate of9.72%and18.69%.2bacterial189and6X and2actinomyces97kyjf13and14had good suppression effect on the hypha growth and germination.6. The application on fields of pepticides and biocontrol agentsThe field tests were operated with four pepticides and four biocontrol agents selected from lab. The results illustrated that the rate of infected plants and the effection of control of thiophanate methyl, mancozeb, Fu Huo land captan reached very significant and of the bacterial189,6X and actinomyces97kyjfl3and14reached significant.