Abstract

SAMANIEGO GAXIOLA, José Alfredo; FONTES PUEBLA, Ana Aurora; TARANGO RIVERO, Socorro Héctor  and  PEDROZA SANDOVAL, Aurelio. Behavior of the Cotton Root Rot (Phymatotrichopsis omnivora) in a Pecan Plant Nursery. Rev. mex. fitopatol [online]. 2014, vol.32, n.1, pp.26-37. ISSN 2007-8080.

Fourteen plots were established in soil with the presence of Phymatotrichopsis omnivora. The objectives were to determine in dead pecans by the fungus in 2013: I) tree death rate versus; ii) epidemiological models for disease development; iii) disease incidence versus population per plot and trees' size; iv) stem diameter versus growth of the principal bud, according to the Julian days in which the tree died; v) mortality of the trees established in plots or bags with soil previously dried versus the ones established in undried soil. Ninety three pecan trees died in 98 days when it rained 5.8mm, but with 58mm, 85 trees died in 48 d. The monomolecular model predominated, which suggests that the inoculum in dead pecan trees did not increased enough to spread the disease into healthy pecan trees during that year. The number of trees per plot versus the mortality had a determination coefficient of 0.905. The disease killed pecan trees trees regardless their size. Bud's size varied greatly for the same stem's diameter, which suggests that, the attack of the fungus to the roots was previous to bud initation. Only the pecan trees established in the undried soil did not die.

Keywords : Phytopathogenic fungi; soil; control.