Agronomy Updates – July 4th

Hi everyone. A few updates for this week. Glad to see the sun again, and hopefully some warmer, drier weather for a bit!

Tracking Emergence

Despite the cool, wet weekend weather, a lot of potatoes are poking through the ground across the province, and a number of fields are progressing quickly. This makes it a good time for you or your crop scouts to assess your fields for emergence.

Emergence isn’t something to be best assessed by driving by the field on the road or laneway…it requires a quick visit into the field, do some counting, and dig up any unemerged seed pieces to assess why they didn’t emerge. Poor emergence can be down to multiple reasons (set rot, black leg, blind sets, seed piece size, improper seed placement), so it’s important to understand what caused poor emergence rates or possibly slowed down emergence of certain seed pieces.

At the bi-weekly fieldworkers meeting yesterday, there were some isolated reports of seed piece decay, particularly in some early planted varieties, but not widespread concerns. To do a quick emergence count of your own, pick at least 5 random spots in your field (throw a baseball or frisbee!) and count 20 hills where there are either viable plants or a missing plant. Where there are obvious misses, dig for a seed piece to see whether it’s a planter skip or compromised seed piece.

Time to Think About Fungicides!

With rapid emergence comes rapid plant growth…and a need for protective fungicides for late blight. Conditions have been ideal for sporulation of late blight in the last week, with a late blight decision support tool that I have been testing showing five straight days of 100% infection potential, if there was late blight spores around. Hopefully it is early for late blight to be around, but a few things to keep in mind:

1. Don’t wait too long to get your first protectant fungicides on. Pay attention to how fast your plants are growing and the windows you have for safely applying crop protectants.

2. If you aren’t doing so already, strongly consider using band-spraying to apply protective fungicides before row closure. This reduces the amount of fungicide used and reduces the amount of fungicide which is sprayed directly on the soil. Products like chlorothalonil (Bravo/Echo) and mancozeb (Dithane/Manzate) bind strongly to soil particles and then can travel with soil to rivers and streams in heavy rainfall events. Keep soil on your field, but also work to keep fungicides off of the soil where possible.

3. Scout your fields regularly, and don’t be afraid to send in samples if you come across something that you can’t easily identify. Last year, most samples that were tested for early blight (Alternaria solani) came back as brown spot (Alternaria alternata), which don’t always respond to the same fungicides. Know what you are dealing with so you can then choose the right products for maximum effect.

4. As I’ve mentioned before, keep an eye on volunteers! They can be a reservoir for late blight, early blight, and PVY if not eliminated. If levels of volunteers are very high in certain areas, consider tillage or mowing to control those volunteers. We are also past the deadline to cover or remove cull piles, so ensure that your cull piles are dealt with immediately!

Spud Smart Webinar: Sugar End Disorder

Spud Smart is hosting a free webinar on Tuesday, July 16th at 2 pm Atlantic Time on the topic of Sugar End Disorder and Stem-End Chip Defect Stress Factors and Management. You can register here for the webinar. If you’re not able to log on that day, Spud Smart has been making these webinars available to watch on their website after the fact.

As always, reach out if you have questions. Enjoy the sun!