Efficacy of Bacillus thuringiensis by using high volume, low volume and ultra low volume applications for controlling the beet armyworm, Spodoptera exigua (Hubner) on asparagus
2003
Achara Tantichodok(Department of Agriculture, Bangkok (Thailand). Plant Protection Research and Development Office. Entomology and Zoology Group) | Penluk Chudee(Department of Agriculture, Bangkok (Thailand). Plant Protection Research and Development Office. Entomology and Zoology Group) | Paisan Ratanasatien(Department of Agriculture, Bangkok (Thailand). Plant Protection Research and Development Office. Entomology and Zoology Group) | Uthai Ketunuti(Department of Agriculture, Bangkok (Thailand). Plant Protection Research and Development Office. Entomology and Zoology Group)
In 1999, the result showed that droplet size of HV application could not be analyzed because the droplet mixed together and run off from leaves of asparagus. The droplet density of both LV and ULV applications showed no significantly different between the top and the middle canopy of asparagus. The droplet density of LV application was 198-209 droplets/square cm and significantly different from ULV application (9-18 droplets/square cm) which less than the standard. In 2001, the application rates of HV, LV and ULV were adjusted to be 120, 40 and 1 l/rai, respectively. Droplet size of HV application showed similar as in 1999 trail. The droplet density of both LV and ULV applications showed no significantly different between the top and the middle canopy of asparagus. The droplet density of LV application was 81-160 droplets/square cm significantly different from ULV application 19-40 droplets/square cm. These results showed that the highly concentration of B. thuringiensis using in a lower volume application is more effective than those with higher application volumes. The application of ultra low volume spray with Micron-Ulva Fan Spray gave the most effective result, but it is not practical. Therefore, the low volume application is recommend for B. thuringiensis to control the beet armyworm on asparagus.
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