Agronomy Update – Sept 14th

Hello everyone,

I’m sure that we’re all nervously watching the updates with relation to Hurricane Lee as it makes its way northward.  I don’t know about you, but I still have some hurricane-PTSD after Fiona.  Thankfully, the current forecast seems to indicate that the impacts of Lee should be much less than either Dorian or Fiona for both wind and rain.  Nonetheless…most growers are telling me that we don’t need another drop of rain…so it’s a waiting game to see how much moisture Lee leaves us with.


Anticipating Tuber Quality Issues:

I’ve already seen indications that we are in for a more challenging storage season.  For most of the Island, the 2023 growing season has already been the wettest on record and we still have a few weeks to go.  Across the Island, we’re already seeing enlarged lenticels and symptoms of water soak and soft rot.  Given conditions, I expect that we’ll also see more cases of pink rot and Pythium leak than normal as well.

More than anything, it is important to minimize taking problematic potatoes into long-term storage.  Some things to consider:

  • Any areas of fields were water has been observed between the rows for more than 24 hours should be flagged off and dug last, if at all. Potatoes from these areas should never be put into long-term storage.  Be generous with where you place your flags…start with where you see water lying and then move another 10-15 metres out from there.
  • All sprayer track rows should also be dug last. I’ve seen water laying in some sprayer tracks constantly for the last month.  These rows are bound to have a high proportion of tubers with water soak and soft rot.  Also, these rows tend to have the highest percentage of greening and off-type tubers.  Definitely dig these rows last (if at all) and either find a way to send them out ASAP or put into short-term storage.
  • Applying phosphorus acid products (Confine/Phostrol/Rampart) going into storage can help prevent the spread of pink rot, but there is no evidence it does anything for Pythium leak and it won’t help soft rot disease (which is bacterial).
  • Nola Olsen of the University of Idaho has generously provided a copy of a recent presentation that she did on early season storage management, complete with her recorded audio.  I have recorded her presentation as a video and uploaded to YouTube.  It is about 40 min long and touches on a number of important topics, including:
    • Monitoring tuber pulp temperatures at harvest
    • Eliminating excess heat from storages after harvest
    • Minimizing shrink while also properly aiding wound healing/curing
    • Dealing with excess moisture from soft-rot diseases.

It is worth your time to watch this presentation by Dr. Olsen before you start storing potatoes this fall.  Dr. Olsen one of the key North American experts when it comes to potato storage.


Pest/Disease Update:

Late Blight:

  • All Spornado sites are negative this week (Sept 12)
  • Last Airspore samples were last Friday, Sept 8th.  Also negative


Grey Mold:

  • Bortrytis spore counts from both Airspore late last week and Spornado this week are very high.
  • Spornado – positive at all sites, ranging from 230 to 36,600 spores per trap.
  • Lots of inoculum around.  If you still have potatoes that need to be protected, now would be a good time for Bravo or Echo.



  • Green Peach Aphid number spiked in West Prince last week with an average of 43 per trap across 15 traps.  Interestingly, GPA numbers were only 2.4/trap in Central PEI and 0.2 per trap in Eastern PEI last week.  Other aphids numbers were 7.5 in the west and less than 1 per trap in the central and east.
  • I don’t have full data from this week yet; however, GPA numbers that I do have access to (in the West) are similar to last week.
  • If you have seed that is not yet killed, I would highly recommend that it be killed as soon as you can. Particularly since with heavy rains forecast for this weekend, you may not be able to get into the fields to spray right away.


Have a safe weekend, and hopefully we don’t get as much rain and wind as forecast!