Research Of Identification And Control Effect Of Huangguogan Anthracnose Pathogen

In this study, Citrus cultivar cv. Huangguogan was took as material, from which we isolated 42 disease pathogens strains. Eight strains (G1-8) were choose to study the pathogenicity, by morphological and molecular identification, initially identified the pathogen of Huangguogan diseases was Colletotrichum gloeosporioides. The G-6 as the research object, determining its biological characteristics and fungicides virulence. Through field control and study, to provide a certain reference value for the identification and prevention of this kind of Huangguogan disease. The main findings are as follows:1. Isolation of pathogen, identification and pathogenicity testInoculation of 8 strains of pathogenic bacteria were lesion, and combined with the pathogenic bacteria of the morphological characteristics and sequence analysis of rDNA-ITS, to determine the cause of Huangguogan anthracnose pathogen was C.gloeosporioides.2. Biological characteristics of pathogensThe optimum growth temperature of Pathogenic bacteria was 25 to 30 centigrade. All light conditions were most conducive to the growth of the mycelium.. The lethal temperature of the mycelium was 58 centigrade for 10min. Pathogen in potato culture medium (PDA) growth was the fastest, daily growth rate reached 12.1mm/d, medium surface to produce orange conidia heap and sporulation quantity was 2.23×107 spores·mL-1. The pH value for mycelium growth was not affected, within the range of pH5-pH 11, the normal growth and the generation of the spores were produced.7 kinds of carbon sources for pathogens have significant impact, which with glucose, starch, lactose as carbon source in the culture medium growth best, growth rate of mycelium were:10.22mm/d,991 mm/d,9.85 mm/d.7 different nitrogen sources with peptone as nitrogen source medium mycelia grew fastest, secondly for sodium nitrate as the nitrogen source in the medium, mycelial growth rate respectively:13.38 mm/d,1.26 mm/d. For the amount of spore produced, glucose and glycerol were the best carbon sources, the spore yield were 2.50×105 spores·mL/-1、2.17×105 spores·mL-1. Peptone and beef extract were the best nitrogen source, the spore yield were 1.19×108 spores·mL-1、 4.83×107 spores·mL-1. For spore germination rate, glucose and sucrose were the best carbon sources in the culture medium. The spore germination rate of different nitrogen sources was less than that of the water control, it indicated that different nitrogen sources had inhibitory effect on spore germination rate.3. Toxicity measurement in pharmacyIn the 7 tested fungicides,60% pyraclostrobin metiram (WG) had good inhibitory effect on mycelia, the inhibition of the pathogenic bacteria by 10% phenyl ether (WG) is relatively strong, the value of EC50 respectively were 17.95μg/mL and 68.74μg/mL.25% ester (EC) was the ether, the value of EC50 was 186.24μg/mL.4. Field control20% Karen (EC) 2000 times liquid was the best control effect of Huangguogan anthracnose, the control effect reached 72%. In the next place were 60% 100 Thai (WG) 1500 times liquid,10% score (WG) 2000 times liquid and 10%difenoconazole (WG) 1000 times liquid, the control effect respectively reached 60%,65.8%,50%.Determination of toxicity in laboratory and comparison of field control effect, indoor virulence measurement provided a theoretical basis and guidance for field control and control. However, there are some differences between the actual field control and efficacy. This is related to the natural environment, the field climate and many other factors. Therefore, the choice of pharmaceutical should be based on the actual effect of the field.