Preemergence Infection of Potato Sprouts by Phytophthora infestans in the Highland Tropics of Ecuador. uri icon

abstract

  • Experiments were conducted to determine whether preemergence infection of potato sprouts by Phytophthora infestans occurs in the highland tropics of Ecuador. In three separate experiments in the field, P infestans was identified on the preemerged sprouts of 49, 5, and 43% of tubers, respectively, which had been removed from soil prior to emergence. Tubers had been planted within 10 in of approximately 300-m(2) plots with mature potato plants severely infected with late blight. Infection potential of potato sprouts also was evaluated in the greenhouse by applying 10-ml sporangial suspensions (50 and 250 sporangia/ml) daily for 10 days to the soil surface of pots planted with sprouted seed potato tubers. The daily inoculation rate of 50 sporangia/ml (15.9 x 10(3) sporangia/m(2)) resulted in sprout infection in 100% of inoculated pots and roughly corresponded to the sporangial deposition accumulated over 24 h in the field. Deposition had been measured at I in from a severely infected potato plot. Our study demonstrated the potential for preemergence infection of potato sprouts by P. infestans in the highlands of Ecuador, where year-round aerial inoculum is present. Preemergence infection is consistent with high levels of disease sometimes seen in recently emerged potato fields. These experiments indicate a need to reconsider disease management approaches.

publication date

  • 2008
  • 2008