Control Effect Of GC16 Series Of Ecological Preparations On Onion Virus Disease And Its Vector Insects

Onion(Allium cepa L.)is a biennial or perennial plant of the Liliaceae family,also known as shallots.Onion is a worldwide vegetable,second only to potato and tomato in production area.At present,China’s onion planting area and total output ranks first in the world.In Inner Mongolia Autonomous Region,the onion industry is developing rapidly,and the planting area is increasing.Onions have become one of the main local vegetables.Hongxiuqiu is the first onion variety independently cultivated in Inner Mongolia.It was independently bred by the Academy of Agriculture and Animal Husbandry of Inner Mongolia Autonomous Region.It is one of the main variety of onion in Inner Mongolia.In recent years,onion virus disease has occurred widely,and it is difficult to control,which seriously affects the yield and quality of onion.Thrips and aphids play an important role in the spread of onion virus disease as vector insects.The control measures commonly used in production are mostly chemical control,but chemical agents cause problems such as environmental pollution and pesticide residues.Due to the high insecticidal efficiency and eco-friendly characteristics of botanical insecticides,it has become a hot spot in the development of innovative pesticides at home and abroad.Therefore,the development of green prevention and control technology based on ecological preparations can fundamentally solve the problem of diseases,and at the same time,it can also promote the growth and development of onions,which is of great practical significance for the rapid development of the onion industry.In this paper,the investigation and research of onion virus disease and its vector insects were carried out,GC16 series of ecological preparations were created,and the control effect on onion virus disease and its vector insects was studied.The main findings are as follows:1.Through the field investigation of onion virus disease,there were three types of symptoms in the field: ⅰ.Discoloration.The color of onion leaves were gray-green and dull.In some parts,yellow-green stripes appeared.In severe cases,the leaves of the plants were fresh and tender but completely lost their green color to light yellow.No onions with whole leaves turn yellow were observed.ⅱ.Deformity.The upright leaves showed a continuous wave-like depression.The curved leaves showed a spiral shape.The onion tubes were constricted and thin,with individual leaves were abnormally long or the middle of the leaves were bent and twisted.Shorter plants were observed.ⅲ.Necrosis.Leaf apex were yellow and necrotic,and some onion leaves have necrotic strips from the apex to the middle of the leaf.The results of field investigation on the incidence of different onion varieties showed that virus disease occurred in all three tested varieties.The incidence of onion Hongxiuqiu was 84.00%,Hongmei was 79.00%,and Jinmei was 84.00%.The statistical conclusion of disease index showed that in the first survey,the disease index of each variety was Hongxiuqiu 53.33,Hongmei 25.33,Jinmei 48;in the second survey,the disease index of each variety was Hongxiuqiu 44,Hongmei 47.33,Jinmei 25.33.There was no significant difference in disease index between varieties.2.The results of the investigation on thrips and aphids,the vectors of onion virus disease,found that the thrips harmed onions and formed white spots,rolled and drooped leaves,and the color of the leaves became lighter.The thrips could be seen moving on the inner wall when the green onion leaves are cutting longitudinally;aphids gathered on the undersides or grooves of leaves to fed themselves.The results of the insect population survey showed that 327 thrips were found on 54 onion plants,with an average of 6 per plant,and a total of 48 aphids were found,with an average of 0.89 per plant.The indoor virulence tests and field control effect of GC16-3 ecological preparation on aphids showed that the LC50 value was 4.623 m L/L;the aphid population reduction rate was 85.42%,and the control effect was 84.92% after 1 day of field application on onion plants;after 3 days of application on onion plants in the field,the insect population reduction rate was 81.25%,and the control effect was 79.90%.The indoor toxicity test and field control effect of GC16-4 ecological preparation on thrips showed that the LC50 value was 7.864 m L/L;after the first application,the thrips population reduction rate was71.25%,and the control effect was 73.96%;after the second application,the thrips population decline rate was 88.38%,and the control effect was 87.86%.3.By studying the improvement effects of GC16-7 ecological preparation on the damage symptoms of onion virus disease,it was found that GC16-7 ecological preparation can reduce and alleviate the damage symptoms of onion virus disease.The GC16-7 ecological preparation was mixed with morpholine guanidine hydrochloride and auxin(composed of gibberellic acid,indole acetic acid and brassinolide)to study the synergistic effect of the GC16-7 ecological preparation.It was found that this compounded mixture had the highest preventive effect on onion virus disease of 90.82% and the lowest of 66.85%;the optimal combination and ratio were the combination of the dilution concentration of GC16-7 standard solution at 75 times,the dilution concentration of 20% morpholine guanidine hydrochloride wettable powder was1500 times,and the auxin was 5500 times.