Agronomy Update – May 12

Hi everyone.  Another wet morning after a couple of good drying days.  Thankfully, the forecast looks a bit more promising later this week for the next while.  I there are quite a few folks that would like to be further along with grain planting so far, but hopefully that will come along quickly.

I can tell you that soil temperatures are still generally cool.  The soil temperature probes that I have installed in Central PEI are reading 7.2C this morning.  They were reading 5C on Monday.  Cold nights take half a day to recover from in terms of soil temps.  With a little higher nighttime temps the rest of this week, that should help warm the soil up a bit.

In my travels this so far this week, I see lots of folks are cutting seed and getting ready for planting.  Just a reminder to ensure you’re keeping that seed dry after cutting, getting lots of air through your seed to prevent soft rot.  And treat that seed carefully….that means no big drops, lowering the boom into the truck, being careful when loading your planters.  Bruised seed will have not only higher risk of infection but also lower yield potential.

Also…cleaning and disinfection around seed cutting and seed transportation is incredibly important!  This should be top of mind for all producers.  Talk to us if you need resources/information on this topic.


Decisions on Pesticide Re-evaluations

PMRA has been releasing a number of decisions on pesticide produce re-evaluations in recent weeks.  The Coles notes on a few of important to potato producers:


  • Both Clothiandin (Titan) and Thiamethoxam (Actara) will continue to be registered for potatoes.
  • Titan will continue to be allowed as a seed-piece treatment, but in-furrow application will be discontinued.  There are also some changes in application rates for most crops.
  • Actara will also continue to be registered, but soil drench application on potatoes has been discontinued.


Lambda-cyhalothrin (Matador/Silencer)

  • Continued registration has been granted for potatoes and a number of other crops.  Cancelled for mustard seed, all feed uses, and some oilseeds.
  • Some new risk-mitigation measures have been added to the label


Pymetrozine (Endevor/Fullfil)

  • PMRA has decided to cancel all outdoor use of this chemistry.
  • Phase out process is 3 years, so still able to legally use for this season


Bifenthrin (Capture)

  • PMRA has granted the one year Emergency Use Authorization for Capture for 2021 for wireworm control.
  • This application was done by Lorraine and Sebastian with the PEIDAL…thanks so much for their assistance with this.


New episode of SpudChat

New episodes of SpudChat are available for download on Wednesdays.  This week, I talk with Sebastian Ibarra, IPM specialist with the PEI Dept of Ag, to talk about integrated pest management and some of the programs that are available to assist PEI producers.  Whether you are doing crop scouting, spore trapping, pest/disease decision tools, or on-farm trials…there may be a program to help you.

SpudChat is now available on almost all podcast platforms…finalizing getting it added to Apple Podcasts, but it should be available everywhere else.  I’ve also added a Podcast link to the top menu of the PEI Potato Agronomy website where you can listen to podcast episodes whenever you want.


Some thoughts on nutrient management

  • Sulfur (S) is a macronutrient that often gets overlooked.  Did you know that a 300 cwt yield of potatoes will remove approximately 10 lbs/acre of sulfur?  Most recommendations that I’ve consulted call for 15-20 lbs/acre of sulfur for potatoes.

    We used to get a lot of “free sulfur” from pollution/acid rain.  With cleaner air quality, that free sulfur is no longer coming.  Also, sulfur can leach from soil (like nitrogen), particularly in sandy soils like we have in PEI.  So work with your agronomist/nutrient management planner to ensure your fertility plan has enough sulfur.  Sources of sulfur include K-Mag (21% S), gypsum (calcium sulfate hydride), ammonium sulphate (AS, 24% S), and manures/compost.

  • Another leachable micronutrient is boron (B), which is often low in a lot of PEI soils.  Many growers are already addressing boron in both their dry fertilizers and some foliar applications.  Most fertilizer applicators are now providing coating products that contain both boron and zinc (Zn), ensuring a more even distribution of these micronutrients through the soil profile.
  • In some soil testing I recently completed, I came up with a few fields that were quite low in manganese (Mn).  These were long-term rotation fields that had a lot of hay crops removed over the years but not much fertilizer or manure put back on.  Often, these “old pasture fields” are high in organic matter but low in a lot of micronutrients…something to consider if you’re taking on ground like this.

    Manganese (different from Magnesium (Mg)) is an essential nutrient in the synthesis of chlorophyll and in cell wall construction, as well as a number of other functions.  There are both dry (manganese sulfate) and liquid manganese products available, but check your soil tests to see what your levels before changing your fertility program.


Final Thoughts:

  • Morgan and I are almost finished soil sampling ahead of this year’s trials.  Thanks again to so many farmers who collaborate with us on trials…without your involvement, we wouldn’t have much of an AIM program!
  • Still looking for growers who are interested in looking at seed size profile or whole vs. cut seed field trials this spring.  Give me a call if you’d like to discuss further.
  • Make sure you are only travelling on fields that are fit for traffic. I’ve seen a number of fields from the road in the last few days where lime or fertilizer was applied to a field under wet conditions, causing ruts.  While this looks like a mess…the real damage is happening 12-18 inches down, where compaction is forming in a place where it’s harder to break it up.  I know everyone is busy and has lots to do…but try and stay off wet fields as much as possible.
  • Morgan and I have been doing a lot of penetrometer testing for compaction as part of our soil sampling process.  Overall…compaction levels are high.  I’ve noticed that a bunch of fields coming into potatoes this year are particularly tight at 9-12 inches, routinely reaching 300-400 psi.  I think a big reason for this in some fields is that the fall of 2018 was so wet and a lot of spuds were harvested in wet field conditions…this likely put a lot of compaction in fields.
  • We have some good resources on compaction and subsoiling on the Agronomy website, and we are doing two different AIM projects on compaction.  I think that it is restricting yields more than we know, because it restricts root growth and access to water considerably.  If you would like to borrow a penetrometer to test some of your own fields, we have an extra one that we can lend out to growers.  Or, Morgan and I can come out and show you how it works and check a few fields with you.

Have a great rest of the week, and good luck to everyone as they are ready to plant.  Stay safe!