Inspection Percentage Of Petals Infested About Forecasting Rapeseed Stem Rot,Mycoflora Analysis On Rape Flower And Selection Of Antagonistic Fungi To Sclerotinia Sclerotiorum

From 2001 to 2002, investigation was carried out on mycoflora of rape petals in ya'an, Sichuan province .1908 isolates were obtained from newly opened petals and senescent petals which were collected from early February to late March at emerging bloom ^ full bloom and fall bloom by interval sowing time. Beside Sclerotinia Sclerotiorum, there were other fungi, such as Aureubasidium spp.,Fusarium spp.,AHernaria spp.,Botrytis spp.,Periconia spp.,Aspergillus spp.,Nigrospora spp.,Peniccillium spp.,Trichoderma spp.,Epicoccum spp.. The dominant mycoflora were Aureubasidium spp , Fusarium spp .and Alternaria spp., Followed by them were Botrytis spp., Periconia spp. and Aspergillus spp. The average isolation frequency ofNigrospora spp.,Peniccillium spp. was lower. Expect for Trichoderma spp. and Epicoccum spp., their isolation frequency were 19.84%, 19.83%, 13.09%, 9.92%, 5.41%, 1.52% and 1.28%, respectively. Result showed these fungi have different colonization abilities on rape petals.Inspection on MDI of rape demonstrated that MPPI (Mean Percentage of Petals Infested) was connected with MDI(Mean Disease Infested).In forecasting rape stem rot ,MPPI on senescent petals in full bloom have more precise than in other stages. In addition, the earlier sowing time and the longer bloom stage was, the higher isolation frequency of Sclerotinia Sclerotiorum was . The bloom stage lasted for 50 days in the first sowing time, when isolation frequency of Sclerotinia Sclerotiorum was 15.95%, but in other two sowing time the isolation frequency were 14.40% and 10.00% respectively, which were lower than in the first sowing time. However, it was found that the differenceof isolation frequency of Sclerotinia Sclerotiorum among three sowing time and stages was not statistically significant.160 isolates were selected from identified fungi from rape to test their antagonistic effect to S. Sclerotiorum by the methods of dual culture, cellophane disk method and enclosed chamber test .The properties for a antagonist, which have been suggested as necessary for S. Sclerotiorum , including hyphal interaction , direct parasitism, strong competitive ability and antibiotic production were observed in vitro. Among them, 10 isolates were selected (A4, F6, Au2, Asl, Bl, Pe7, Au6, As2, F3, Pe5), antagonism and activity of which were strong.