Study On Dynamic Changes Of Occurrence Regularity And The Control Technology Of Aphid Transmitted Tobacco Virus Disease

Tobacco virus diseases are very important destructive diseases,which frequently occurres in tobacco fields in China.From the 60's of the 20^th century to now,aphid transmitted virus disease like cucumber mosaic virus disease,potato virus Y disease etc.become more serious from year to year in Shandong province.In recent years,along with the weather changing,the expanding of the shelter fields,the increase of the number of the aphids lived pass through winter and the extending of the vegetation period,the aphid transmitted virus diseases became the most important disease and the most important fact that curb the Weifang tobacco industry to be developed persistingly,stably and healthily.Our research results showed that the occurrence of the aphid transmitted virus have some regular dynamic changes interact with the weather facts.If the emergence time of the aphids was brought forward,the first peak hours of the migratory flight of the alatae also would be ahead of schedule.In 1996 and 1997,the first peak hours of the migratory flight of the alatae appeared about on May 25^th to June 15^th,in the year 2004,the alatae appeared earlier and last longer together with large number.The first peak hours of the migration was about on May 11^th to 20^th and the continuance period was about 12 days.The second peak appeared just 15days after the first peak.In 2005,the first migration peak hours of Zhucheng tobacco fields was on May 24^th to 29^th and Anqiu tobacco fields was on May 19^th to 24^th,so the peak time was short and the number was little.The first migration peak hours of the year 2005 was delayed 10 days.Compare with 1996 and 1997,the first migration peak was 5 to 10 days ahead of schedule.The time of the disease appearance varied largely among different terrains.The data showed that the time of the diseases appearance moved up gradually.In some years the diseased tobacco plants were even found in seed beds.The peak hours of aphid transmitted virus disease appeared about 15 to 30 days after the first migration peak of the alatae. varied with different year.If the temperature of the winter was higher and drought during April to June,the time of the disease appearance would be ahead of schedule.If covered with micro-aperture membrane earlier and uncovered later,the incidence of a diseases would be lower and the effects of controlling disease by using micro-aperture membrane would be better.The effect of controlling disease by glisten membrane was limited within distance.When aphids were not very serious,the effect of glisten membrane to drive aphids away was in evidence within 3 to 5 ridges in a field,but beyond this distance,the effect was not notable,The effect would dramatically decline when the distance increasing.In 2003,the aphids pest was at a average degree, the incidence of the disease of all the 4 model fields was 10.8%,61.5%lower than CK.,and the control effect was 73.8%.In 2005,the aphids pest was under average level.The first migration peak was ion May 19^th to 24^th,and the time was short,the number was little.So the glisten membrane was effective,The ridge covered with glisten membrane and it's 5 neighboring ridges showed no disease tobacco plant,the incidence of disease of the whole field was 18.2%, and the relative control effect was 58.5%.If the aphids burst to a large number,the glisten membrane had a limited effect to drive aphids away,and the relative control effect would decline.The experiments results showed that covering planting with voile could control aphids effectively,and prevent aphids to transmit virus to the tobacco plant.The chemical elements and the aroma of tobacco leaves have no difference with the untreated leaves.The effect of current available chemicals for controlling tobacco virus disease were 30%to 50%,though some how they have some effect,but in general,they could not curb the virus diseases effectively.