Study On Identification And Comprehensive Control Of Pink Snow Mold In Heilongjiang Province

In recent years, with the expanding of winter wheat planting areas in Heilongjiang province,some plant diseases happened, causing serious losses to production, in which snow mold was one ofthe important diseases endangering winter wheat production. In the early spring, in regions wherewinter wheat has just turned green and the grounds were still covered with much snow, the winterwheat were often infected by snow mold resulting in the wheat seedlings withering instrips andpieces, which directly affect the production.Snow mold was infected by various pathogens with low temperature tolerance, harming wheatseedlings and it was a kind of disease leading to seedling rotting. There are no comprehensive studyabout the distribution and extent of the damage, species and biological characteristics of thispathogen, methods of resistance identification, resistance of germplasm resources and effectivemeasures to control the snow mold in Heilongjiang province. So we proceeded a systeminvestigation for the distribution, species and extent of damage caused by snow mold inHeilongjiang province, and then conducted an study for its biological characteristics, resistance ofgermplasm resources and control by fungicides, etc, which had a great significance for the effectivecontrol of snow mold and popularization of winter wheat in Heilongjiang province.（1）Diseased winter wheat plants were collected from nine districts of Heilongjiang provincein April2011and2012, The pathogen of winter wheat snow mold in Heilongjiang province wasidentified through morphological characteristics and pathogenicity. The results showed that winterwheat snow mold in Heilongjiang province was pink snow mold, caused by Gerlachia nivalis (Ces.ex Sacc.)W.Gams et E.Mull. It was the first report that this disease was found in Heilongjiangprovince since planting “Dongmai1” in2007.（2）Biological characteristics of Gerlachia nivalis were studied. The results showed that theoptimum temperature for mycelial growth was20-25℃, the suitable pH was around7. Alternatedlight conditions benefit to mycelial growth, and the best carbon and nitrogen source was starch andbeef exteact, respectively. Lethal temperature of the pathogen is at50℃for10min. The optimumconditions for spore reproduction was15℃at pH=7, the suitable carbon and nitrogen source aremaltose and sodium nitrate, respectively. Lacking of nitrogen and carbon influence more severelyon the pathogen growth than lacking of magnesium, ferrum, kalium and phosphor.（3）Identification technology for the resistance of winter cereal to Gerlachia nivalis at seedling stage was studied. The optimal identification method of winter cereals resistance toGerlachia nivalis was that the seedling leaves were sprayed by105spore·mL-1at one-leaf age.（4）Use the identification method, the resistance of8germplasm resources of winter cerealwas identified with9strains of Gerlachia nivalis. The results showed that for the8winter cerealmaterials, the resistance of “Dongmai1”was the strongest, immune to strain Gn-rh2and resistant tothe other8strains; the resistance of377was the weakest. The virulence of9strains also existdifferences, the virulence of strain Gn-rh4was the strongest and the virulence of strains Gn-rh2isthe weakest.“Dongmai1”,377,607and608were selected as candidate differential hosts forpathogenicity differentiation of Gerlachia nivalis.（5）For the13kinds of fungicides to Gerlachia nivalis,70%hymexazol wattable powder(WP) showed the best effect and the effective concentration (EC50) was2.88mg·L-1,the inhibitingrate of spores germination was65.4%; Following was12.5%myclobutanil EC with EC50of4.62mg·L-1; with the EC50of2614.00mg·L-1,50%carbendazim WP showed the lowest inhibitioneffect to Gerlachia nivalis. In the pot experiment,50%procymidone wattable powder for60mg·L-1showed the best effect to Gerlachia nivalis, the relative control effect was95.7%; following were50%procymidone WP for20mg·L-1and12.5%myclobutanil EC for10mg·L-1.（6）The advantage fungi groups carried at the surface of winter wheat seeds from10areas ofHeilongjiang province in2011were mainly the Alternaria and Penicillium genus. Gerlachia nivaliswere not found from the external and internal of seeds, which accounted for the little possibility thatwinter wheat seeds in the ten regions carried Gerlachia nivalis in2011.