| Owing to the extensive planting of single varieties, changes in the agricultural tillage system and the climate, corn stalk rot has become increasingly serious in China recently. Corn stalk rot, one of the most devastating soil-born diseases, has spread to many maize production area and cause severe yield loss every year. It has been a potential threat to maize production all over the country.As the pathogen of corn stalk rot is complex and occurs at the late milk stage of the corn, the disease is difficult to control by conventional techniques. The key control teniques of corn stalk rot is planting resistant cultivars, seed treatment, and chemical control. In this paper, we identified the resistance of major corn cultivar and breeding lines, selected effective biological preparations and agro-chemicals. The main results were read as follows:1. We investigated the resistances to stalk rot among various maize hybrids and inbreds, and found that there were 16 species resistant to stalk rot in 35 hybrids. During the two years field experiment, the resistance of Qidan No.1 and Nuoda No.1 were the highest, whose average incidence was under 5%. As the highly susceptible species, we found Sanbei218, Jiyu6 and Ludan818's incidence reached more than 80%.Especially, the incidence of Ludan818 was 91.7%. In 50 inbreds, Xianyu335?, TL10B-6903-134 and Indonesial were highly resistant to corn stalk rot; 1x9801, (1x93111x03-2) S4 and H21 are the most infected.2. The biological activities of twelve different fungicides comprising of single-dose and mixtures were tested against the Pythium aphanidermatumand the Fusarium graminearum by toxic media method in lab. The results indicated that when the ECso was 50%, metalaxyl-M showed strong virulence against Fusarium graminearum, and ECso for mycelial growth was 0.31mg/L. However, carbendazim showed the strongest virulence against Fusarium graminearum and EC95 for mycelial growth was 33.84 mg/L. The virulence of carboxin+thiram was the weakest and the EC50/EC95 was 3279.45/236412.10 mg/L. Carbendazim, Metalaxyl-M · fludioxonil, tebuconazole fludioxonil · Saphire,azoxystrobin showed strong virulence against Pythium aphanidermatum. The virulence of carbendazim against Pythium aphanidermatum was also strong and the EC50/EC95 was 0.87/21.60mg/L. The weakest virulence was azoxystrobin-fludioxonil metalaxyl-M and the EC50/EC95 was 299.14/57808.22mg/L.3. We choose the selected fugicides in potted experiments to test the control effect of them on corn stalk rot. Through the germination rate, root length, chlorophyll content and incidence of maize, we drew a conclusion that in the soil with a large number of pathogens, the highest germination rate was the seed coating and the second was biocontrol bacteria and potash. From the plant height results, the seed coating and soil treatment promoted the corn growth. The height of plant seed-coated with azoxystrobin, metalaxyl-M · fludioxonil, fludioxonil · saphire, azoxystrobin, thiamethoxam · fludioxonil · mefenoxam was 51.00cm, 56.33cm,66.33cm,62.00cm, respectively. The chlorophyll content of the corn treated with Rhizomes Bao and thiophanate-methyl was the highest of 4.42mg/g. The control effect of the tebuconazole, azoxystrobin and metalaxyl-m on corn stalk rot caused by Fusarium graminearum was the best,the number of control efficiency are 16.67,17.50,15.00 and 14.29. The control of the azoxystrobin, Li haoyuan, Fertilizer ofpotassium (225kg/hm2), and isopyrazam on Corn stalk rot caused by Pythium aphanidermatum was the best,the number of control efficiency are26.67,8.18,25.00,34.00. With the does of potash increasing, the incidence of corn stalk rot is reducing.4. Through the two years field experiment, the control effect of Carbendazim in two years all reached more than 60%.The seed coating with hiamethoxam*fludioxonil·mefenoxam also have a good control effect on corn stalk rot, which reached more than 65%. The control effect of 225kg/hm2 potash and the biocontrol bacteria of zhong nong fu yuan reached 92.23% and 88.31%, respectively. |
PDF Full Text Request