The Study Of Isothiazolinones Applied In Controlling Gray Mould And Sclerotinia On Cucumber

The compounds with higher inhibitory activity to B. cinerea and S. sclerotiorum was establishedthrough testing the biological activity of6isothiazolinone compounds and their packed mixedformulations BIT, OIT, MIT, CMIT/MIT, CMIT, DCMIT to Botrytis cinerea and Sclerotiniasclerotiorum. The synergistic action of the mixture of CMIT with MIT(3:1)was found throughevaluating the co-fungitoxicity by Wadley formula. CMIT/MIT14AS was developed throughoptimizing the formulation of CMIT/MIT. The efficacy of CMIT/MIT14AS in controlling sclerotiniaand gray mould on cucumber was established through the field trials and the application techques ofCMIT/MIT14AS in controlling cucumber sclerotinia and gray mould were clarified. The major resultsof research are listed as follows:1Inhibition of isothiazolinone compounds to Botrytis cinerea and Sclerotinia sclerotiorumThe bioassay results in vitro and vivo indicate that,6isothiazolinone compounds from strongerinhibitory activity to weaker inhibitory activity to mycelial growth of B. cinerea were DCMIT>CMIT> CMIT/MIT> OIT> BIT> MIT;6isothiazolinone compounds from stronger inhibitory activityto weaker inhibitory activity to mycelial growth of S. sclerotiorum were OIT> DCMIT> CMIT/MIT>CMIT>BIT>MIT;6isothiazolinone compounds from higher inhibitory activity to lower inhibitoryactivity to conidial germination of B. cinerea were OIT> DCMIT> CMIT> CMIT/MIT> BIT> MIT;6isothiazolinone compounds from higher control effect to lower control effect to gray mould oncucumber cotyledons were CMIT/MIT> DCMIT> CMIT> BIT> MIT> OIT; in potted cucumberseedlings soaking root test,6isothiazolinone compounds from the higher control effect to lower controleffect to sclerotinia on cucumber in vivo were DCMIT> CMIT> CMIT/MIT> BIT> MIT.2The synergistic action of the mixture of CMIT with MIT(3:1)The co-fungitoxicity of the mixture of CMIT with MIT(3:1)was evaluated with Wadley formula, theresults indicate that the mixture of CMIT with MIT(3:1)showed synergistic effect in inhibition tomycelial growth of B. cinerea and S. sclerotiorum in vitro, and in controlling gray mould andsclerotinia on cucumber. The synergistic ratio (SR) of the mixture of CMIT with MIT(3:1)was0.63ininhibition to conidial germination of B. cinerea and showed additive effect.3Optimization of the formulation of CMIT/MITThe optimum formula of CMIT/MIT AS was established through study of the appropriateformulation of the mixture of CMIT/MIT (3:1) and optimization of the formulation. In the optimumformula, OP-10was selected as a surfactant, xanthan gum was selected as a tackifier, a small amount ofS408was added as an assistant of surfactants. The pH of the prepared CMIT/MITAS is2.98, foamingcharacteristics was4mL(in standard hard water diluted85times), dilution stability (in standard hardwater diluted200times), storage stability at low temperature and elevated temperature are qualified.4Control effect of CMIT/MIT AS to gray mould and sclerotinia on cucumber in the fieldsThe results of the field efficacy trials showed that CMIT/MIT AS gave good control to gray mould and sclerotinia on cucumber. To cucumber gray mould, controlling efficacy of78.9%～91.4%wasgiven by spray of CMIT/MIT AS at the rate of47.25~94.5g a.i./hm~2, significantly higher than thatgiven by the spray controlling efficacy of pyrimethanil40SC at the rate of562.6g a.i./hm~2(78.9%～91.4%), the controlling efficacy of CMIT/MIT AS at the highest rate of94.5g a.i./hm~2(90.3%~91.4%)was not significantly different from that given by boscalid50WG(90.2%~90.5%).To cucumber sclerotinia, controlling efficacy of51.0%～75.4%was given by spray of CMIT/MIT AS atthe rate of47.25~94.5g a.i./hm~2, the controlling efficacy of CMIT/MIT AS at the highest rate of94.5g a.i./hm~2(73.3%~75.6%) are not significantly different from that given by iprodione50WP(73.3%~75.6%).