两种有机硫熏蒸剂处理连作土壤对三七根腐病复合症的防治效果

Control efficacy of soil fumigation by Dazomet and K-Vapam on root rot complex in Panax notoginseng continuous cropping field

测试了有机硫熏蒸剂大扫灭（Dazomet）对三七（Panax notoginseng Wall．）根围几种主要病原生物：线虫、细菌和真菌的最低灭生浓度（MBC值）分别为≥7．8、≥31．2和≥125μg／mL。4种主要病原真菌：立枯病丝核菌（Rhizoctoni solani）、根腐病菌毁坏柱孢霉（Cylindrocarpon destructant）、镰孢霉（Fusarium spp.）和黑斑病交链孢（Altervaaria tenus）的MBC值分别为≥31．2、≥62．5、≥125和≥125μg／mL。钾-威百（K-Vapam）对线虫、细菌和病原真菌的灭生活性与Dazomet相当。连作三七田播种前和移苗前用98％大扫灭粉粒剂20～40dm^2和35％钾-威百液剂30～50mL／m^2进行耕作层土壤熏蒸处理，对三七出苗和成苗率无显著影响；杂草和线虫发生量比对照分别减少90％～95％。播前处理比对照苗病发生率降低45．0％～82，5％，移苗前处理苗病发生率降低35．0％～50．0％。适当充足的土壤含水量、适时彻底的土壤毒气排除对提高药效和避免残毒对后茬药害至关重要。

The minimum biocidal concentration （MBC） of two organic sulfur fumigants for rhizospheric pathogen of P. notoginseng was investigated. The results showed that the MBC of Dazomet for nematodes, bacteria and fungi were ≥7.8, ≥31.2 and ≥125μg/mL, respectively, and those for fungi Rhizoctoni solani, Cylindrocarpon destructant, Fusarium spp. and Alternaria tenus were ≥31.2, ≥62.5, ≥125 and ≥125μg/mL respectively. K-Vapam showed the same biocidal activity as Daz, omet. Soil fumigation by 20-40 g/m^2 98% Dazomet granule and 30～50 mL/m^2 35% K-Vapam liquid before sowing and （or） transplanting did not significantly influence the seedling emergence and establishment of P. notoginseng, but reduced the population densities of weeds and nematodes by 90% ～ 95 %. The pre-sowing treatment reduced the incidence of diseased seedlings by 45.0% ～ 82.5%, and the pre-transplanting treatment reduced the incidence of diseased seedlings by 35.0%～50.0%. Adequate soil moisture content and timely thoroughly discharging the toxic gas in fumigated soil are important to improve the effect of fumigation and avoid the damage to afterreap crop caused by residual toxicant.