Caracterización de aislados de Neofusicoccum parvum asociados al cancro de tallos y ramas en Cannabis sativa L. en Uruguay

The cultivation of cannabis is relatively new in Uruguay, having a momentum and growth from the year 2013 after the enactment of Law No. 19.172, being the first country in the world to regulate the production of cannabis for recreational, medicinal and industrial use. The crops are distributed throughout the country, having a greater influence in the south and south-east, occupying around 456 hectares in the open air and some 90.000 m² of protected cultivation. The objective of the present work was to characterize isolates of Neofussicocum parvum by means of morphological and pathogenicity methods in Cannabis sativa plants of the variety Fenochis. The isolates were planted in two culture media, PDA and AA with sterile pine needles. In PDA medium, the isolates were incubated at 25 ºC in the dark to characterize the colonies and pigment production at 3, 8 and 16 days of incubation. In AA medium with the addition of sterile pine needles, they were incubated at 25 ºC, with a 12-hour photoperiod of near ultraviolet and fluorescent light for 7 weeks in order to favor the formation of structures and characterize the conidia. Subsequently, the inoculation was carried out in the Phytopathology Laboratory of the Faculty of Agronomy (Montevideo) using three (Cluc F, Migues 1 and Migues 14), inoculating a total of 45 plants distributed in three blocks with five repetitions. The symptoms observed consisted of necrosis at the stem level, with generalized wilting and death of the plant with the advance of the disease, where the production of pycnidia could be observed on the affected tissue. Of the plants with symptoms, isolation was carried out from stem pycnidia, coinciding with N. parvum. This work is the first to test the pathogenicity of N. parvum isolates in C. sativa cultivation, confirming the presence of stem and branch blight in Uruguay.