Antagonismo bacteriano como control biologico de pudricion humeda en plantas de papa (Solanum tuberosum L.).

Bacterial soft rots occur most commonly on vegetables that have fleshy storage tissues. They are found all over the world and cause serious diseases of crops in the field, in transit, and especially in storage, resulting in greater total loss of produce than any other bacterial disease. Microbial antagonism was studied as possible tool to control soft rot of potato tubers (Solanum tuberosum L.), disease caused mainly by E. carotovora group of bacteria. To evaluate the antagonistic capacity of the bacterial isolates used, two completely randomized field blocks were established with 4 treatments and 3 repetitions. The field test were conducted in the localities of Fresia and Remehue (Xth Region, Southern Chile), using cv. Kennebec. A rich organic soil (peat) and a bacterial suspension were used as cell carries to transport the antagonistic isolates. Induction of soft rot on potato tubers was conducted after harvest. Two methodologies and different testing dates were established. First, potato tubers were immersed in water inside plastic bugs, then, each tuber was individually wrapped with moist paper towel and covered with alusa plat. Potato tubers weight differences determined before (initial weight) the rot induction and the remaining tuber tissue (final weight) were established as percentage for each one of the treatments. The use in field test of antagonistic isolates of E. carotovora did not significantly affect potato tubers yield. On the other hand, soft rot incidence on potato tubers was greater in Remehue than in the locality of Fresia. The effect of the isolates used as biocontrol agents on soft rot bacteria carried by daughter tubers was not significantly reduced and it could be due to a non diminution of the disease in the harvested tubers. An increasing amount of storage time of the potato tubers resulted in a larger amount of soft rot. Also, the evolution of rot by immersing potato tubers in water, yielded a greater amount of tissue, less than in the process of wrapping tubers with moist towel and "alusa plat".