Ginseng Crop Update – May 25, 2023

Posted on May 25, 2023 by Sean Westerveld

It looks like most areas escaped a frost last night, mostly due to a breeze that continued all night that mixed up the air. There is a slight risk again tonight with calmer air, but forecast dewpoints are +1C for Delhi, which would decrease the risk of a severe frost.

There has been a lot of damage reported from last week’s freeze, mostly for gardens that were not protected with row covers. These gardens will be prone to foliar diseases, especially next week when temperatures and humidity increase. Ensure gardens are protected with fungicides for both Alternaria and Botrytis before the warm-up.

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Frost Potential for Ginseng May 25 and 26, 2023

Posted on May 23, 2023 by Sean Westerveld

Here we go again on the risk of frost for the ginseng growing areas. The risk appears to be lower at this time but the forecast dewpoint on Weather Underground for Delhi is -1C. Low temperatures are forecast to be between 1 and 3C, so this event would most likely be a ground frost rather than a solid freeze, but again, forecasts tend to change and often the temperatures can end up slightly cooler forecast. For more info refer to my post from last week: https://onspecialtycrops.ca/2023/05/16/understanding-frost-risks-for-lavender-may-16-2023/

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Understanding Frost Risks for Lavender – May 16, 2023

Posted on May 16, 2023 by Sean Westerveld

I have had several inquiries about the potential for frost damage to lavender from the frost events in the forecast because of previous events that devastated lavender in some areas. Spring frost damage is relatively rare in lavender. I am aware of two major events. The first occurred in May of 2015 in southern areas of the province. That event occurred on May 23 and temperatures recorded in the area at eye level (which forecasted temperatures are based on) were -4C. On the ground, the temperature was several degrees lower because it was a very dry airmass with very low dewpoints. Flower buds were clearly visible at the time. All of the green growth on all plants that were not covered was killed in the event.

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Risk of Frost for Ginseng this Week – Plan Now – May 15, 2023

Posted on May 15, 2023 by Sean Westerveld

Although the weather forecasts generally still show low temperatures above freezing every night this week in the ginseng production area (as of Monday at noon), the risk of frost especially Wednesday night is relatively high. This is because of the following:

  1. Longer range forecasts (beyond 24 hr) are often conservative until the event approaches. It has happened many times that forecasts show lows above freezing and then the forecast lows suddenly drop the day before the event.
  2. Humidity is forecast to be low, and we have not had rain in over a week, allowing the surface of most fields to be dry. Dry air cools much faster than moist air. Weather Underground, the only forecast I can find that includes dewpoint, shows the dewpoint as -4C Thursday morning. That means that dew or frost would not form until it hits that temperature and is often a good indication of how cold it could get on a clear and calm night at the ground level.
  3. All forecasts show clear skies Wednesday night.
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REMINDER – ONHoppenings Lunch and Learn session next Tuesday May 16 @ noon

Posted on May 11, 2023 by Melanie Filotas

Just a reminder that the first ONHoppenings Lunch and Learn session of 2023 is scheduled for next Tuesday, May 16 at noon. OMAFRA specialists Evan Elford and Melanie Filotas are back with two online Zoom discussions for Ontario hop growers for the 2023 growing season.  Each session will feature an initial 30-45 minute presentation from Melanie or Evan, after which we will open it up for participants to ask questions about any topic pertaining to hops.  This month we will focus on pests and disorders to watch out for in 2023. Melanie will be providing an overview of the major pests of hops and their approximate timing during the growing season. Evan will provide an update on nutrient deficiency symptoms in hops based on a recently completed project conducted in Simcoe. Participants will then have the opportunity to ask Melanie or Evan questions about agronomics, pests or any timely issue affecting hops. 

Attendance is free and open to everyone, however you must pre-register to receive the meeting log-in details. Register in advance by clicking on this link: https://us06web.zoom.us/meeting/register/tZEuceGoqjwjG9MZdZHRRcmCbofYoIQEwLqo

Anyone wishing to ask questions in advance can email Melanie (melanie.filotas@ontario.ca) or Evan (evan.elford@ontario.ca) by 8:30 the day of the session OR enter it in the question field during registration, and we will do our best to have an answer for during the session. 

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Ginseng Crop Update – Spring Pests – May 5, 2023

Posted on May 5, 2023 by Sean Westerveld

The prolonged cool period over the past two weeks has delayed ginseng emergence, but plants should emerge rapidly over the next week. There has been at least some precipitation 13 of the last 14 days keeping the soil very moist over that period. A freeze to around -2°C occurred last week in most areas, but dewpoints were high, suggesting that temperatures at the ground level were not any colder. It is unlikely this caused any significant damage unless emerging older plants were exposed due to thin straw cover. Temperatures have been cool since then. In some recent springs, prolonged cold temperatures without a significant frost have caused incomplete development of the tops including distorted leaves and shorter stems, which then led to higher Alternaria problems later in the year. While it has been cool over the past week, it has not been as cool as some previous springs due to a very moist airmass that prevented night temperatures from dropping too much. It is unlikely temperatures were cold enough to cause damage, but this is something to watch out for.

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