咯菌腈对四种牡丹叶片病原真菌的抑制活性

Inhibitory Activity of Fludioxonil to Four Pathogenic Fungi of Peony Leaves

【目的】探究咯菌腈对牡丹黑斑病菌(Alternaria suffruticosae)、黄斑病菌(Phyllosticta commonsii)、腔孢叶斑病菌(Hainesia lythri)和叶霉病菌(Cladosporium paeoniae)菌丝生长、孢子萌发、芽管伸长及产孢的抑制活性,分析咯菌腈在牡丹病害化学防治上的应用前景。【方法】采用菌丝生长速率法测定咯菌腈对菌丝生长的抑制活性,采用涂布平板法测定咯菌腈对孢子萌发、产孢时间及产孢量、芽管伸长及芽管和孢子形态的影响。【结果】咯菌腈对腔孢叶斑病菌菌丝生长的抑制作用最强,EC_(50)为0.01μg·mL^(-1),其次为黑斑病菌和黄斑病菌,分别为0.07和0.35μg·mL^(-1);咯菌腈对4种病菌的孢子萌发均有较强的抑制作用,对腔孢叶斑病菌的抑制作用最强,其EC_(50)为1.26μg·mL^(-1),对其他3种病菌孢子萌发的EC_(50)在3.27—3.45μg·mL^(-1);0.1μg·mL^(-1)咯菌腈对4种病菌分生孢子芽管伸长的抑制率在40%—70%,表明咯菌腈对4种病菌分生孢子芽管伸长均有明显的抑制作用,浓度越大抑制作用越强,各浓度间差异显著,其中对腔孢叶斑病菌芽管伸长抑制的EC_(50)为0.04μg·mL^(-1),抑制作用最强,对其他3种病菌芽管伸长的EC_(50)在0.08—0.22μg·mL^(-1);咯菌腈对黑斑病菌和黄斑病菌分生孢子和芽管的致畸作用强烈,可导致孢子及芽管膨大、过度分枝,而对叶霉病菌和腔孢叶斑病菌致畸作用较弱,芽管及孢子形态基本正常;咯菌腈可推迟黑斑病菌、黄斑病菌及叶霉病菌的产孢时间,对黑斑病菌产孢量的抑制作用最强,EC_(50)为0.05μg·mL^(-1),对叶霉病菌次之,EC_(50)为0.38μg·mL^(-1),但对腔孢叶斑病菌产孢有促进作用。【结论】咯菌腈对牡丹黑斑病菌及腔孢叶斑病菌的菌丝生长、孢子萌发及芽管伸长均有很强的抑制作用,但对腔孢叶斑产孢具有一定的促进作用;对叶霉病菌和黄斑病菌孢子萌发及芽管伸长、黄斑病菌菌丝生长及叶霉病菌产孢的抑制作用强烈;由于咯菌腈内吸活性较弱,无法抑制已侵入牡丹叶片的病原真菌的生长,故建议作为保护剂在病害发生前施用。

[Objective]The objective of this study is to make clear the activity of fludioxonil on mycelial growth, conidia germination, germ tube elongation and sporulation of four peony foliar pathogenic fungi, including Alternaria suffruticosae, Phyllosticta commonsii, Hainesia lythri and Cladosporium paeoniae, and to analyze whether fludioxonil could be used in the chemical control of peony disease. [Method]The inhibitory activity of fludioxonil against mycelial growth was measured through a mycelial linear growth test and the efficacy of fludioxonil on conidial germination, germ tube elongation and sporulation was determined on the PSA or KDA amended with fludioxonil at various concentrations. [Result]Fludioxonil had a strongest inhibition on mycelial growth of H. lythri with the EC_（50） of 0.01 μg·mL^（-1）, followed by 0.07 μg·mL^（-1） of A. suffruticosae and 0.35 μg·mL^（-1） of P. commonsii. Fludioxonil could strongly inhibit the conidia germination of four peony pathogenic fungi and the inhibitory activity on H. lythri was the strongest, with the EC_（50） of 1.26 μg·mL^（-1）. The EC_（50） to other three fungi ranged from 3.27 to 3.45 μg·mL^（-1）. Fludioxonil could also strongly inhibit the germ tube elongation of four fungi, and the suppression ratio of 0.1 μg·mL^（-1） fludioxonil reached 40% to 70%. The germ tube of H. lythri was the most sensitive to fludioxonil, and the EC_（50） was 0.04 μg·mL^（-1）. The EC_（50） of fludioxonil to other three fungi＇s germ tube elongation varied from 0.08 to 0.22 μg·mL^（-1）. Fludioxonil could cause the abnormality of conidia and the germ tube of A. suffruticosae and P. commonsii, including expanding of spore and germ tube and excessively branching of germ tube. However, the effect of fludioxonil on that of H. lythri and C. paeoniae was unconspicuous. Fludioxonil could delay sporulation of A. suffruticosae, P. commonsii and C. paeoniae. The EC_（50） of A. suffruticosae sporulation was 0.05 μg·mL^（-1）, followed by the 0.38 μg·mL^（-1） of C. paeoniae, whereas fludioxonil could promote the sporulation of H. lythri. [Conclusion]Fludioxonil had a strong inhibitory activity on the mycelial growth, conidia germination and germ tube elongation of A. suffruticosae and H. lythri, but could promote the sporulation of H. lythri. Fludioxonil could also inhibit powerfully conidia germination and germ tube elongation of P. commonsii and C. paeoniae, mycelial growth of P. commonsii and sporulation of C. paeoniae. Fludioxonil should be used preferentially as a curative fungicide to avoid the pathogenic fungi infection, as it could not be absorbed by the plant tissue and inhibit the fungi that had penetrated and parasitized the plant.