Grape growth enhancement and disease promotion by microecologics agents in Baotou

Abstract：【Objective】The study was carried out to clarify the effect of microecologics Lvkangwei and Lvdikang on the growth and disease incidence of field grown grape, and explore the best application plan, so as to produce safe grapes efficiently. Lvkangwei and Lvdikang are microecologics in different dosage forms mainly composed of three strains of bacillus. They are used to improve the micro-enviroment of plants by applying to the above or the below ground.【Methods】Rain-sheltered‘Suffolk Red seedless’and open field‘Kyoho’grown in Baotou were used as materials for the experiment from May to September 2018, and five treatments were performed in a randomized block design. Treatment 1 was control, where water was sprayed evenly on the front and back sides of the leaves. Treatment 2 involved conventional chemical control scheme with no chemicals used from May 11 to June 2 but later with sprays of 40% chlorothalonil diluted 600 times, 25% metalaxyl· propamocarb hydrochloride diluted 700 times , 40% chlorothalonil diluted 600 times, or 70% Propamocarb diluted 1 000 times. Treatment 3 involved root irrigation of Lvdikang at 500 dilution times and foliage spray of Lvkangwei diluted 700 times for seven times. Treatment 4 was root irrigation of Lvdikang diluted 500 times and foliage spray of Lvkangwei diluted 700 times for four times, followed by conventional chemical application for the last three times. Treatment 5 was root irrigation of Lvdikang diluted 500 times alone for seven times. The interval between applications in all treatments was about 15 days. The diameters and lengthsof the upper, middle and lower current season shoots, and the length and width of the 3rd, 4th, and 5th leaves in each shoot were measured from the day before each application until the first pruning. Relative chlorophyll content was measured one day before each application. The disease index of downy mildew in‘Kyoho’grape was surveyed on August 21 and September 3, 2018, and control effect was calculated. Yield per plant, 100-grain weight and soluble solids were measured at harvest.【Results】The average growth of shoot width of‘Suffolk Red seedless’and‘Kyoho’applied with Lvkangwei and Lvdikang at the same time was 0.123 cm and 0.263 cm, respectively, which were 2.16 and 4.61 times that of the control at the same stage. Shoot length growth in the early stage was greater than the late stage. In the treatment of applying Lvkangwei and Lvdikang at the same time, the shoot length growth was 36.96 cm and 53.82 cm in‘Kyoho’and‘Suffolk Red seedless’, respectively, which was the largest among all treatments, while shoot length increase in the control was only 24.06 cm and 47.91 cm in ‘Kyoho’and‘Suffolk Red seedless’, respectively. The effect of microecologics on leaf expansion in the two varieties of grapes was unstable. The chlorophyll content at each stage in the treatments with microecologics application was significantly higher than that in the treatments with no microecologics. Growth increase in both varieties reached the highest value on July 3. The relative chlorophyll content in vines treated with microecologics reached the highest value of 54.2 and 57.8 at time of the sixth application, while water control was only 51.7 and 53.0 in‘Kyoho’and‘Suffolk Red seedless’.‘Kyoho’began to develop downy mildew in mid- August. Seven applications of irrigation with Lvdikang and foliage sprays of Lvkangwei during the growing season showed the best control effect on downy mildew in‘Kyoho’grape, which was 72.73% and 75.68%. In treatment 4 with the two microecologics applied three times and the fungicides applied three times, the control effect was 54.55% and 49.55%; the control effect with the applications of only Lvdikang for seven times was 58.59% and 57.66% ; while the use of the four fungicides was only 60.61% and 38.74%. The yield per plant in‘Kyoho’and ‘Suffolk Red seedless’treated with microecologics was 2.1 and 2.6 times that of the control, and the 100-grain weight was 136.65 g and 67.66 g higher than that of the control, respectively.【Conclusion】 Applying microecologics seven times from the leaf-expansion period to the harvesting period to both the above and below ground has a good effect on vine growth and control of downy mildew and can be used as alternatives to chemicals.