BRESSAN, W.

FIGUEIREDO, J. E. F.

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Seed treatment with Streptomyces spp. strains inhibit Colletotrichum Sublineolum insorghum seed.BRESSAN, Wellington - FIGUEIREDO, José Edson FontesEmbrapa Milho e Sorgo, Microbiology Department, Rod. MG 424, Km 65, 3570 I-970,Sete Lagoas, MG, Brazil. E-mail: bressanéàcnpms.cmbrapa.br.The effectiveness of Streptomyces spp. strains to control Colletotrichum sublineolum (Ces.)G. W. Wils. (syn. C. sublineolum Henn. In Kab. and Bubák) races and isolates were evaluatedin vitro and on sorghum seeds. The ability of Streptomyces spp. strains to produce chitinasewas tested by qualitative method followed by quantification.The present study included nine.physiologic races (31 A, 15A, 3 IB, 30B, 15B, 13B, 31C, 30C, 29E), four isolates (51, 57, 126,148) of C. sublineolum and four strains of Streptomyces spp. (DA UFPE I 1470, DAUFPE14632, CMS 2A, CMS 4A). The effectiveness of Streplomyces spp. strains to control C.sublineolum races and isolates, in vitro, was evaluated by recording the diameters (mm) of thezone of mycelial inhibition. Variation in the inhibition pattern of four Streptomyces spp. strainswas observed with respect to different races and isolates of C. sublineolum. The strainDAUFPE 1J 470 was the most effective in inhibiting ali the C. sublineolum races and isolates(54 to 60 mm inhibition zone) followed by the strain DAUFPE 14632 (18 to 55 mm inhibitionzone). The strain DAUFPE 11470 could reduce the fungal incidence in sorghum seed by 88.5to 99. I% for the most virulent race and least virulent isolate. No control was achieved byisolates CMS 4A and CMS 2A. Ali four Streptomyces spp. strains produced chitinase enzyme,but the activity was highest in the DAUFPE 11470. The results indicate that Streptomycesspp. strains have potential as biological control agents against C. sublineolum races andisolates in sorghum seeds and the chitinase activity may be involved in the biocontrol processoHowever the biocontrol effectiveness depends on the strains to be used as biological controlagent and the physiological race and isolate of C. sublineolum.Keywords: Biocontrol, Antracnose, Chitinase, Actinomycete

Seed treatment with Streptomyces spp. strains inhibit Colletotrichum Sublineolum in sorghum seed.

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