Cancro dos ramos do cafeeiro (CRC) : variabilidade de genótipos resistentes e eficácia de fungicidas
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Data
2024-04-26
Autores
Rocha, Matheus Ricardo da
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Universidade Federal do Espírito Santo
Resumo
Brazil is the world's largest producer and exporter of coffee (Coffea spp.) and the second largest exporter of conilon coffee. However, fungal diseases such as stem canker of coffee trees (SCC), caused by Fusarium spp., have the potential for damage up to 100% in susceptible C. canephora genotypes. The disease is currently being managed without specific control methods, such as resistant genotypes and fungicides. In this sense, the objective was to characterize the resistance of clones and the effectiveness of fungicides for the control of SCC, caused by F. solani. For the resistance experiments, seedlings of 36 C. canephora clones, 20 from the robusta varietal group and 16 from the conilon varietal group, were inoculated with F. solani using the Mycelial Inoculation in Wounded Stems (IMC) method, transferring discs of mycelium and spores of the pathogen, grown on potato-dextrose-agar (PDA) for 10 days, for longitudinal sections in the stem of each sampling unit. The quantified disease data over time were subjected to analysis of variance, Scott-Knott mean tests and bootstrapping with the aid of R software, grouping clones according to resistance. For the variable internal lesion length (cm) and according to the Scott Knott tests, the clones Imbigudinho, Bamburral, Bicudo, P2, AD1, A1, AP and Peneirão were grouped among the most resistant of the conilon varietal group, while G20, L33, VR4, R22, R40 and 7 were the most resistant clones of the robusta varietal group. For F. solani mycelial growth inhibition and chemical control experiments, ten fungicides (Met+Flu, Dif+Pid, Cyc, Tia, Tia+Flu+Met, TioMet+Flu, Pid, TioMet, Pro+Nap and Flu) were tested in preventing mycelial growth F. solani in increasing doses between 0.0001-10000 µg.mL-1 in PDA culture medium. The EC50, effective concentration to inhibit 50% of the pathogen, estimated according to the log-logistic model LL2.3 in the R software, was between 0.06-5.77 µg.mL-1 in our results, and only the fungicide Flu was considered inefficient, with EC50 greater than 50 µg.mL-1 . At greenhouse, four doses of nine fungicides were sprayed preventively before inoculation, inoculated with F. solani by the IMC method on C. canephora seedlings with three pairs of leaves (clone LB1). Based on Kaplan-Meier curves estimates in the R software and log-rank tests, fungicide application tested for reducing symptoms and dry branches. The fungicides Pro+Nap, TioMet, Dif+Pid, TioMet+Flu, and Cyc were the most efficient, with no plant drought occurring at the highest doses under study, with a probability of plant survival of up to 100% throughout the entire experiment. The results obtained in this study will be essential to establish more efficient integrated management of SCC, an important disease expanding in C. canephora producing regions in Brazil
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C. canephora , Controle químico , Fusarium spp. , Fusarium solani , Resistência