Agronomy Update – Aug 2nd

Hi everyone,

Spotty rainfall last night.  Some areas got very little, others got a full inch.  Largest total in Kings County from what I’ve seen, who needed rain the most.  Forecast is variable for the next 7 days…hopefully a bit more rainfall is coming.

The crop is still looking quite good, and early bulking is in full force in most fields.  I was with growers digging a few tops today that are already finding 8-10 oz tubers.  Some seed is going to be killed soon as it has already reached the optimum size profile. Seed growers will need to keep a close eye on size profile over the next week.

 

Spore Trapping:

  • No late blight spores were detected in PEI this week.  Late blight spores were detected at one site in NB last week but has not been detected since.  No foliar late blight has been confirmed east of Ontario.
  • Grey mold (Bortrytis) spores were very high in about half of the Spornado samples this week, without a clear pattern across the province.  As these spore traps collect spores continually through the week, it is quite possible that these numbers will be higher than for Airspore, which only collects at a point in time 3x per week.  Grey mold spores have started to increase now in some areas that canopies are mostly at row closure.  Variability across the province is likely due to variety effect, fungicide programs, and weather patterns.
  • Grey mold is most worrisome when we start getting daytime temperatures consistently below 23 C (with cooler nights) and lots of free moisture.  If the forecast looks cooler and wet later in August, switching up your fungicide program to include chlorothanonil (Bravo/Echo) or a product like Miravis Duo or Scala would be advised.

 

AIRSPORE July 29th July 31st
Region Early Blight Brown Spot Grey Mold Early Blight Brown Spot Grey Mold
West Prince 19 11 18 0 0 9
East Prince 117 0 59 423 11 96
Queens 0 0 43 98 7 110
Kings 6 0 362 95 0 560

 

  • Early blight increased mid-week this week compared with earlier in the week, likely due to dry and warm conditions.  There is significant early blight pressure in some fields/varieties but most growers have it well under control.  I have observed some brown spot symptoms, but pressure is generally low, and spore counts have also bee low.
  • Grey mold counts look to be a little higher Wed than Mon this week.  As stated above, we should watch for a change to cooler, wetter conditions for grey mold growth.  Dakota Russet is a variety that has a particular susceptibility to grey mold, so Dakota growers should likely ensure that Bravo is in their late season fungicide program a couple of times.
  • If you have observed early blight or brown spot in any fields and would like to submit a sample for resistance testing, please contact me!  You can either drop off samples at the office, or we can arrange to collect samples.

 

Pest/Disease Update:

  • Most growers are reporting the Colorado potato beetles continue to be seen, but foliar sprays are in generally proving quite effective.  I was in one field today where a 2nd generation of adult beetles are chowing down on foliage but larvae were effectively killed by a foliar spray.  Keep a close eye on fields!
  • As we start to lose flowers on a lot of fields, be on the lookout for white mold (Sclerotinia).  Grower experience indicates that Mountain Gems are a bit more susceptible to white mold than other varieties.
  • A few growers are reporting significant corn borer damage from egg masses detected in early July, but this is very spotty across the province.  I was in a field today where some corn borer damage was originally thought to be blackleg symptoms but on further inspection, we easily found entry holes and larvae in the stalks.  We will watch to see if there is a 2nd generation this season.
  • Tarnished plant bugs and leafhoppers are also being reported by scouts and growers.  These insects may be present but may not cause much damage.  Consult with your agronomy team to assess whether the number of insects observed reaches the threshold for application.

 

Aphid Alert:

Region Week ending Number of traps Potato Aphid Buckthorn Aphid Greenpeach Aphid Other Aphid Tarnished Plant Bug Bird Cherry-Oat Aphid Total Average pert trap
CENTRAL PRINCE 3-Aug-24 5 0 0 0 5 0 0 5 1.0
CENTRAL QUEENS 3-Aug-24 8 0 0 0 0 0 0 0 0.0
EAST KINGS 3-Aug-24 2 0 0 0 0 0 0 0 0.0
SE QUEENS/KINGS 3-Aug-24 2 0 0 0 0 0 0 0 0.0
WEST PRINCE 3-Aug-24 12 0 0 0 21 0 0 21 1.8
Total 29 0 0 0 26 0 0 26 0.9

 

No aphids were counted this week in Queens and Kings Counties, and aphid numbers in Prince County are down significantly from the week before.  All of the aphids trapped were “other aphids”, non-colonizing aphids.  Still no green peach aphids detected.  The aphids numbers continue to be higher in West Prince than the rest of the province; that being said, some of the traps being used up west are bowl traps that may have the ability to catch more aphids, so this should be factored into our comparisons.

There will not be a full agronomy update next week as I’ll be travelling out of province, but if there are any late blight or other pest updates that need to be communicated, I will be sure to send something along.

Have a great end of the week,

Ryan