Bulletin number 2, 6/11/20

Welcome to the second spore trapping report for 2020. All spore traps have now been deployed around the state, with the exception of the American Falls spore trap. Download the spore trapping potato data here and the sugar beet spore trapping data here. Both excel spread sheets require a password to open then. Email us to request access to the data.


  • No spores of Phytophthora infestans (late blight), Alternaria solani (early blight) or Sclerotinia sclerotium (white mold) were detected this week.
  • This week we have seen several critical humidity periods (CHP), weather stations where we had two CHPs on consecutive days include Glenns Ferry, Kimberly, Rupert, Aberdeen and Ashton. This occurred on the 7th and 8th of June. However, the other model we use for forecasting late blight (MPM) suggests the risk remains low this week, especially considering that crops in the Aberdeen and Ashton area are just starting to emerge or have just emerged.
  • With relatively cooler and windy conditions in these areas and crops not yet at row closure, we do not recommend changes to spray programs but please remain vigilant in those areas where we had two consecutive CHPs.

Sugar beet

Spores of Erysiphe betae (sugar beet powdery mildew) were detected this week at the west Treasure Valley site (one day), Parma (two days) and Glenns Ferry (2 days). No spores were detected in Kimberly. We have increased our scouting for sugar beet powdery mildew at Parma. Typically we see the first visual symptoms on leaves 2-3 weeks after the first detection in the spore trap.