Method comprising the steps of: - collecting a sample of a plant or of a medium in which the plant is growing, - identifying a pathogen in the sample, - identifying signs of a resistance of the pathogen to a control agent, • wherein the identification of the pathogen and the identification of the signs of a resistance is done by means of sequencing of individual nucleic acids or individual peptides in the sample, wherein sequences of nucleotides or sequences of amino acids are ascertained in the sequencing of the individual nucleic acids or individual peptides, wherein the sequences of nucleotides or sequences of amino acids are compared with reference sequences, characterized in that the sequencing is done in two phases, a first phase and a second phase, • wherein, in the first phase, during the sequencing of each nucleic acid or each peptide, the respectively ascertained sequence is compared with at least one pathogen sequence, and ▪ if the ascertained sequence does not match the at least one pathogen sequence, further sequencing of said nucleic acid or said peptide is aborted, • if the ascertained sequence matches a pathogen sequence, a pathogen having the pathogen sequence is ascertained and the ascertained pathogen is used to ascertain at least one resistance marker, and a switch is made to the second phase, • wherein, in the second phase, sequences of the nucleic acids or peptides in the sample are compared with the at least one ascertained resistance marker and/or with a resistance-free sequence, wherein a resistance-free sequence is a succession of nucleotides or a succession of amino acids of a pathogen that does not exhibit signs of a resistance of the pathogen to a control agent. - collecting a sample of a plant or of a medium in which the plant is growing, - identifying a pathogen in the sample, - identifying signs of a resistance of the pathogen to a control agent, • wherein the identification of the pathogen and the identification of the signs of a resistance is done by means of sequencing of individual nucleic acids or individual peptides in the sample, wherein sequences of nucleotides or sequences of amino acids are ascertained in the sequencing of the individual nucleic acids or individual peptides, wherein the sequences of nucleotides or sequences of amino acids are compared with reference sequences, characterized in that the sequencing is done in two phases, a first phase and a second phase, • wherein, in the first phase, during the sequencing of each nucleic acid or each peptide, the respectively ascertained sequence is compared with at least one pathogen sequence, and ▪ if the ascertained sequence does not match the at least one pathogen sequence, further sequencing of said nucleic acid or said peptide is aborted, • if the ascertained sequence matches a pathogen sequence, a pathogen having the pathogen sequence is ascertained and the ascertained pathogen is used to ascertain at least one resistance marker, and a switch is made to the second phase, ▪ if the ascertained sequence does not match the at least one pathogen sequence, further sequencing of said nucleic acid or said peptide is aborted, • if the ascertained sequence matches a pathogen sequence, a pathogen having the pathogen sequence is ascertained and the ascertained pathogen is used to ascertain at least one resistance marker, and a switch is made to the second phase, • wherein, in the second phase, sequences of the nucleic acids or peptides in the sample are compared with the at least one ascertained resistance marker and/or with a resistance-free sequence, wherein a resistance-free sequence is a succession of nucleotides or a succession of amino acids of a pathogen that does not exhibit signs of a resistance of the pathogen to a control agent.