Research On Occurrence Rules And Control Of Maize Dwarf Mosaic Disease In Weibei Dry Land

Maize dwarf mosaic disease, caused by maize dwarf mosaic virus(MDMV) transmitted in a non-persistent manner by many species of aphids, is an important viral disease in the maize production. It occurs worldwide and reduces maize yield and quality seriously. It is a kind of systemic disease with characters of explosion, migration and intermittent. The disease was first reported in 1968 at Xinxiang of Henan province in China. It has occurred mainly in north and northwest of China with a yield loss by 20%-80% and become one of a major problem to limit maize production in China.The occurrence rules of Maize dwarf mosaic disease and the vector aphids were studied through field investigation on fixed corn plants in fixed places and yellow sticky boards in corn field in 2014 and 2015. Seven species of aphids, including the cotton aphid(Aphis gossypii Glover), the grain aphid(Macrosiphum avenae Fabricius), the greenbug(Schizaphis graminum Rondani), the green peach aphid(Myzus persicae Sulzer), the soybean aphid(Aphis craccivora Koch), the bird-cherry aphid(Rhopalosiphum padi Linnaeus) and the corn leaf aphid(Rhopalosiphum maidis Fitch)were collected from the corn field survey in Weibei dry land. Three aphids population peaks happened at the end of May, late June and middle July in Heyang county in 2014. The major species was cotton aphid. Maize dwarf mosaic disease appeared on 12 th June. The number of newly infected plants increased rapidly between 10 th June and 24 th June. And another peak took place between 30 th June and 15 th July. The first peak was higher than the second. The disease incidence kept stable after 20 th July. There were three aphids population peaks occurred in Pucheng county in 2015. The first two came about late May and beginning of July. The major species were the grain aphid. The third one happened at late June. The major species was cotton aphid. Maize dwarf mosaic disease came into sight on 26 th May. The number of newly infected plants increased rapidly between 20 th May and 5th June. And another peak occurred between 14 th June and 5th July. The first peak was lower than the second. The disease incidence kept stable after 10 th July.In 2014 and 2015, the disease control tests were carried out with methods of seed coating and seedling spraying a mixture of Dufulin, a new plant virus resistant agent, and pymetrozine, which led to the effect of killing vector aphids and activating immune resistance of plants. Seed coating dosage was 15 g 30% Dufulin WP and 10 g 25% pymetrozine SC with 1 Kg maize seeds. Seedling spraying dosage was 15 g 30% Dufulin WP and 10 g 25% pymetrozine SC with 15 Kg water. Results of the two years field trials showed that seed coating and seedling spraying the mixture of Dufulin and pymetrozine had a good effect on controlling maize dwarf mosaic disease. After treatments of seeds coating and three times seedling spraying, the disease incidence reduced from 85.00% to 45.00%, with a 47.06% control effect and 51.07% yield increase in 2014. And better results obtained in 2015, treatments brought the incidence down from 80.50% to 34.00%, with a 57.76% control effect and 63.05% yield increase.