The following fungicides were tested: pencycuron;
captan + benomyl; carboxin + thiram; triadimenol; triadimenol + pencycuron;
triadimenol + pencycuron + tolylfluanid; pencycuron + tolylfluanid; triadimenol
+ tolylfluanid; and difenoconazole. The mixture of triadimenol +
pencycuron + tolylfluanid gave 100% control. Captan + benomyl and
difenoconazole were least effective, with 54.1 and 36.5% infection,
respectively. Therefore, a semi-selective medium consisting of antimicrobial
agents such as pencycuron 50 mg L-1, tolclofos-methyl 10 mg L-1, streptomycin
sulphate 100 mg L-1, chloramphenicol 100 mg L-1 and chlortetracycline 100 mg L-1
was developed using potato dextrose agar as the basal medium. The procedure
involved screening of candidate fungicides, developing a suitable combination of
antimicrobial agents, assessing the proposed semi-selective medium and
adjustment of pH of the medium to 5.
Results indicated that 12.5% pencycuron and 10% tolclofos-methyl were effective against black scurf disease caused by R solani on potato tubers, when applied as a dressing of infected seed potato tubers before planting, at 0.25 and 0.2 g a.i./1 kg tubers, respectively. The effectiveness of these two treatments was 84.3-84.8% in 1998, and 99.2-99.3% in 1999. An analytical method using a macroporous diatomaceous earth column and florisil cartridge for cleanup procedure was developed for determination of butachlor and pencycuron in vegetables and rice. Butachlor and pencycuron were extracted from crops with acetone and the concentrated extract was transferred into the MDE column, eluted with n-hexane. The eluate was concentrated and applied on a florisil cartridge. The cartridge was washed with 5% diethyl ether in n-hexane, and then eluted with 15% E/H and 15% ethyl acetate in n-hexane. Butachlor residue in fraction I was determined by GC-ECD Pencycuron residue in fraction II was determined by HPLC-UV at 248 nm. Chinese mustard and rice samples were fortified with butachlor and pencycuron at levels of 0.25-0.75 ppm and analysed. The recoveries of butachlor and pencycuron were between 84.9-94.9% and 88.3-94.8%, respectively. Dichloromethane was used as the solvent for the extraction of the pesticides. Quantitative analyses for iprodione, iprodione metabolites, etofenprox, metsulfuron-methyl, tebufenozide, pencycuron, hexythiazox, teflubenzuron, flufenoxuron, chlorfluazuron, 5-OH-MSO2 and sethoxydim yielded recoveries in the range of 93.5% to 107.9%, with a coefficient of variation less than 10%. As pretreatment, pesticide residue from 20.00 g of sugar was extracted, then evaporated under reduced pressure. The resulting residue was adjusted to 2.00 ml by adding methanol. From this methanol solution, a 20 micro l sample was injected into the HPLC system with UV-VIS photodiode array detection. Isolates of anastomosis group 2-1 and AG3 were sensitive to pencycuron, unlike isolates of AG5 and AG8, which were insensitive.
Results indicated that 12.5% pencycuron and 10% tolclofos-methyl were effective against black scurf disease caused by R solani on potato tubers, when applied as a dressing of infected seed potato tubers before planting, at 0.25 and 0.2 g a.i./1 kg tubers, respectively. The effectiveness of these two treatments was 84.3-84.8% in 1998, and 99.2-99.3% in 1999. An analytical method using a macroporous diatomaceous earth column and florisil cartridge for cleanup procedure was developed for determination of butachlor and pencycuron in vegetables and rice. Butachlor and pencycuron were extracted from crops with acetone and the concentrated extract was transferred into the MDE column, eluted with n-hexane. The eluate was concentrated and applied on a florisil cartridge. The cartridge was washed with 5% diethyl ether in n-hexane, and then eluted with 15% E/H and 15% ethyl acetate in n-hexane. Butachlor residue in fraction I was determined by GC-ECD Pencycuron residue in fraction II was determined by HPLC-UV at 248 nm. Chinese mustard and rice samples were fortified with butachlor and pencycuron at levels of 0.25-0.75 ppm and analysed. The recoveries of butachlor and pencycuron were between 84.9-94.9% and 88.3-94.8%, respectively. Dichloromethane was used as the solvent for the extraction of the pesticides. Quantitative analyses for iprodione, iprodione metabolites, etofenprox, metsulfuron-methyl, tebufenozide, pencycuron, hexythiazox, teflubenzuron, flufenoxuron, chlorfluazuron, 5-OH-MSO2 and sethoxydim yielded recoveries in the range of 93.5% to 107.9%, with a coefficient of variation less than 10%. As pretreatment, pesticide residue from 20.00 g of sugar was extracted, then evaporated under reduced pressure. The resulting residue was adjusted to 2.00 ml by adding methanol. From this methanol solution, a 20 micro l sample was injected into the HPLC system with UV-VIS photodiode array detection. Isolates of anastomosis group 2-1 and AG3 were sensitive to pencycuron, unlike isolates of AG5 and AG8, which were insensitive.
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