23 Jul Agronomy Update – July 23

The rainfall on Sunday & Monday was most welcome, and hopefully more will come in the near future. While rainfall totals are quite variable across the province, it looks like most of the province got between 15 and 25 mm over the two days.  I noticed that some fields that hadn’t quite filled the rows last week are at full canopy cover today.

I was out in a few fields yesterday checking on trials. On early planted fields, we are in early bulking, while later planted fields are closer to tuber initiation. I haven’t done any set counts yet, but from what I’m seeing so far, tuber number per plant looks to be about average.

In general, the crop looks really healthy. I’m not seeing a lot of insect damage or foliar disease symptoms in the fields I’ve visited, and most folks in my network are reporting similarly. With some further timely rains, we should be on track for a good crop.

Colorado Potato Beetle control:

I’m getting questions about Colorado potato beetle control, as we are starting to get to the end of the window for efficacy of the in-furrow neonic products, and some producers are seeing resistant CPB that need additional levels of control.

A few suggestions regarding CPB control:

• Pay attention to thresholds as well as stages of larvae when scouting.
• If you’re only seeing significant numbers of adults and larvae on the perimeter of the field, consider only spraying the outside edges of the field.
• If spraying multiple times per season, it is recommended to alternate chemistry. So far in PEI, resistance levels to these other chemistries appears to be much less than in other parts of Canada. Foliar CPB options include:
  • Group 5:  Delegate, Success, Entrust
  • Group 6:  Minecto Pro (with Group 28)
  • Group 28:  Coragen, Vayego, Verimark, Harvanta
  • Group 15:  Rimon, Cormoran (targeted for control of young larvae, not adults or older larvae)
  • Group 30:  Cimegra
• Under AIM, we are doing a CPB insecticide efficacy trial at Atlantic Agri-Tech this summer.  We will have results to share with you later this year.
• In previous research by AAFC under the last cluster, we are seeing reduced susceptibility of the Group 5 and Group 28 chemistries in PEI, with more evidence of resistance to the Group 5 products than the Group 28. Almost all samples in 2022 had reduced susceptibility (30-70% mortality) for the in-furrow products (Actara/Titan)

Air Spore Report:

• No late blight spores in PEI or NB.  Maine continues to report LB spores but no foliar disease.  Late blight has been confirmed in Ontario (Dufferin County).
• Early blight and brown spore counts are largely zero across the province, except for a couple individual fields.
• Grey mold spores are also quite low.

Aphid Alert:

• Aphid numbers are trending downward slightly this week (2.9/sample down from 3.7 last week) but are still higher than this time last year.
• The majority of aphids continue to be non-colonizing aphids. No green peach aphids were found last week or so far this week.
• Seed growers should continue to be diligent with oil applications and aphicide applications as needed.

I’ve had a couple of calls regarding what aphicide options there are, to change modes of action and avoid insecticide resistance issues.  Below is a list of some options.  Note that this is not an exhaustive list and is not sorted by efficacy.

Group 1B:        Cygon 480-AG, Lagon 480 E

Group 3:           Decis, Matador, etc.  Note:  Green peach aphids have been shown to be fully resistant to Group 3 (synthetic pyrethroids) in PEI, with lower levels of resistance observed in other species.

Group 4:           Closer, Sivanto Prime   Note:  Group 4 is the same insecticide group (neonicitinoids) that includes Titan and Actara.

Group 15:        Cormoran (with Group 4A)

Group 9:           Sefina

Group 23:        Movento

Group 28:        Exirel, Minecto Duo (with Group 4A)

Group 29:        Beleaf

Additional Pest/Disease Notes: 

• European corn borer egg masses are being detected across the province, with many at blackhead stage or emerging.  Incidence is not uniform across the province or within regions.  Large numbers of moths were trapped the week of July 7-11 in the PEI Dept of Ag Pest Monitoring Program.  Numbers in potato fields appear to be elevated last week
• Volunteer potatoes are very prevalent this year, especially close to woods/hedgerows. Growers should be paying attention to last year’s potato fields and scouting for volunteers, especially those not chewed down by potato beetles. There is a new factsheet on volunteer management on the Agronomy Site.
• I’m getting very few reports of foliar disease.

Weather Station Data:

 The PEI Agri-Watershed Partnership, in collaboration with UPEI and myself, are in the process of getting several of the UPEI weather stations back up and running this growing season.  Some must be repaired after not being serviced for a couple of years, and some work needs to be done to get them all reporting on the PEI Climate App that was designed a few years ago.  In the meantime, individual stations can be accessed on the Agronomy Site under the Weather tab on the header bar. There are also links to the East Prince Agri-Environment Association sites, the PEI Department of Agriculture stations as well as the COCORAHS network.

Please have patience as we get the UPEI stations back up and running. I hope that we’ll have a better platform to share weather station data by the fall, and then we also hope to build some additional tools for producers using this data.

UPEI Sustainable Ag Conference:

UPEI is hosting a Sustainable Agriculture Conference on August 5^th and 6^th in Charlottetown. More on this event is available at https://atlanticsustainableag.ca/. Registration is now open, with a fee of $125.

2025 AAFC Harrington Stakeholder Day

Date: Wednesday, July 30th (Rain Date Thursday, July 31st)

Time: 10:00am to 3:00pm

Location: Harrington Research Farm, 1200 Brackley Point Road, Harrington, PE C1E 1P9

Please sign up with this link https://www.signupgenius.com/go/60B094EA8AE29A2FB6-57336747-2025 or email charlotte.thompson@agr.gc.ca

Have a great rest of the week,

Ryan