Response of tomato (Solanum lycopersicum) varieties to Clavibacter michiganensis subsp. michiganensis infection

<p><em>Clavibacter michiganensis</em> subsp. <em>michiganensis</em> causes bacterial wilt and canker disease of tomato. The objectives of this research were i) to characterize and identify the most aggressive Cmm in Chignahuapan, Puebla, ii) to evaluate the tolerance in two phenological stages of 10 tomato varieties to infection by CP_Cmm1 in the greenhouse and the <em>in vitro</em> sensitivity of the bacteria to bactericides. 12 Cmm isolates were collected from tomato plants and a strain (CP_Cmm-1) with greater aggressiveness was selected according to the time of manifestation of symptoms in plants of var. Reserva. Afterward, the strain was inoculated by cutting with scissors embedded in a suspension with 3 x 108 UFC mL-1 in two phenological stages (at five and 10 true leaves). Symptoms were evaluated for 30 days after inoculation. Additionally, the sensitivity of CP_Cmm-1 to eight commercial bactericides <em>in vitro</em> was evaluated. The results showed that the CP_Cmm-1 strain was identified with 97% similarity with the API20 E system, positive with DAS-ELISA, and by PCR it showed 96.6% identity with <em>Clavibacter michiganensis</em> subsp. <em>michiganensis</em>. The Saher variety showed greater tolerance to infection (* = p?0.05) both in the stage of five and 10 leaves; the varieties Sv4401, Nápoles, and Súper óptimo showed greater susceptibility in the five-leaf stage. The Sv4401 variety was highly susceptible in both stages. Neither variety was resistant to infection by CP_Cmm-1. The use of the Sahel variety and kasugamycin could reduce the damage of this bacteria.</p>