|Keywords:||柑桔立枯病;黃龍病;媒介昆蟲;柑桔木蝨;族群消長;likubin;huanglungbin;greening, vector;Diaphorina citri;population fluctuation;Incidence and spread of citrus likubin in relation to the population fluctuation of Diaphorina citri||Issue Date:||Sep-1990||Publisher:||中華植物保護學會||Journal Volume:||32||Journal Issue:||3||Start page/Pages:||167-176||Source:||植物保護學會會刊||Abstract:||
The population of psyllid Diaphorina citri kuwayama, a vector of likubin-greening. began to increase in late Febuary and reached its peak in April, then decreased to a relatively low level after June of 1983 under greenhouse conditions. The population fluctuation of the vector in 1984 was similar to that in 1983 under the same conditions. In the field, number of psyllids increased in the likubin-affected test plot since mid-March (mid-spring), and reached the highest density in late April and early May (early summer). The high population density lasted 2-3 months depending on environmental factors. Generally, psyllids increased after the new flushes coming out from citrus trees in the next spring. Based on our observations, psyllid fluctuation was mainly influenced by the flushing rhythm of citrus trees. Our results also showed that population density of psyllids in the test plot was higher in the first year than that in the second year. This may be due to the poor growth of likubin-infected trees. To determine the time of transmission of likubin pathgen by psyllids, the results showed that higher transmission rates occurred in March, April and May (mid-spring to early summer) both in greenhouse and field experiments. Based on the results of the population fluctuation of psyllids and the transmission rates from different months, it is suggested that the timing of likubin infection may be also the timing of new sprouts flushing in field, but March to May will be an important period of infection in a year. Of 60 healthy Ponkan trees planted 10 meters away from the likubin-infested field, none was found to be infected with likubin under the intensive insecticide sprayings in a 2-year period. Conversely, 30 originally healthy plants without control were infected in likubin-infested field. These results indicated that insecticide application effectively prevented the spread of the disease. Therefore, it is suggested that intensive spray of insecticides from mid-March to early May and early eradication of likubin-infected trees be carried out in order to reduce the spread of likubin in Taiwan.
|Appears in Collections:||植物病理組|
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