Screening Of New Fumigants And Study On The Application Technology

With the development of agriculture in China, income of farmers has been rising in the recent tenyears. But the soilborne disease is becoming more and more serious at the same time. Using thefumigants to soil disinfect is the most economical and effective method now. Methyl bromide (MB) isthe most traditional soil fumigant. But as a stratospheric ozone depleting compound, it is scheduled tobe withdrawn from routine use by2015in China. So to find new fumigants and technology toalternative MB for controlling soilborne diseases is the urgent task for us now.In the paper, the combination treatments of1,3-dichloropropene+dazomet (1,3-D+DZ) andChloropicrin+Formaldehyde (Pic+F) were evaluated. In the laboratory study, the activity on root-knotnematodes (Meloidogyne spp.), two major soilborne fungi (Fusarium spp.and Phytophthora spp.) andthe seeds of two major weed species (Digitaria sanguinalis and Abutilon theophrasti) were evaluatedand the better one was selected for further evaluation in cucumber fields. The results were as follows:1. Laboratory studies of1,3-D+DZ found that nearly all of the tested1,3-D+DZ displayedpositive synergistic activity on root-knot nematodes with at least91%reduction. All of the tested1,3-D+DZ also displayed positive synergistic activity on two major soilborne fungi and the seeds of twomajor weed species. The reduction in Fusarium spp. and Phytophthora spp. was at least99%and92%,respectively, for the various rates tested. The four rates of1,3-D+DZ provided100%control ofDigitaria sanguinalis and Abutilon theophrasti. Based on the laboratory studies,1,3-D+DZ was furtherrecommended for field trials.2. Laboratory studies of Pic+F found that nearly all of the tested Pic+F displayed positivesynergistic activity on root-knot nematodes. But only the highest dose combination displayed goodactivity (86.6%), the others bellow80.0%. Nearly all the combinations for Pic+F displayed synergisticactivity on Fusarium spp. and Phytophthora spp. But all the reductions were bellow70.0%. All of thetested displayed positive synergistic activity on Digitaria sanguinalis and Abutilon theophrasti, butresults were unsatisfied. So Pic+F was not further recommended for field trials.3. Field trials of1,3-D+DZ revealed that the combination of1,3-D and DZ (at10+25g m-2)successfully suppressed Meloidogyne spp. root galling, sharply reduced Fusarium spp. andPhytophthora spp. and maintained high cucumber yields. The combination treatment of1,3-D+DZ wasmore effective than1,3-D or DZ alone and provided results similar to methyl bromide with respect topest control, plant mortality, plant height, yield and income. All of the treatments were significantlybetter than the non-treated control.In conclusion, combination of1,3-D and DZ offers an efficient alternative to MB for cucumberproduction. The recommended methods of1,3-D+DZ are as follows: DZ is applied by mixing soil,followed by1,3-D applied either by manual injection or by chemigation, then laying out barrier sheets.