Cover crop videos

Thursday, September 16, 2021

Perennia's Sonny Murray and Rosalie Gillis-Madden
discussing cover crops.

Did you plant a cover crop this summer?  Curious about how it will perform through the fall and into the winter?  Check out Perennia’s Cover Crop video series!  
To highlight a couple of the hits:

Status report on Cucurbit Downy Mildew

Thursday, September 2, 2021

As of Wednesday, September 1st, cucurbit downy mildew has been found in Annapolis, Kings, and Hants Counties.  While all Cucurbits are susceptible to downy mildew, there are different Clades which affect different subsets of the Cucurbit Family.  Clade I predominantly infects watermelon, pumpkin, squash, and zucchini.  Clade II predominantly infects cucumbers and cantaloupes.  So far, we have only found downy mildew in cucumber fields, suggesting that we have Clade II. 

There is a great Cucurbit Downy Mildew Diagnostic Key, which might help you determine if you have downy in your field

Downy mildew spores blow in on storm systems from the United States, so it is possible that Thursday's storm will bring in Clade I, so growers should be aware.  Downy mildew cannot overwinter in Nova Scotia unless the infection spreads to greenhouses.  Please reach out to Rosalie Gillis-Madden, Perennia’s Vegetable Specialist by email or cell (902-670-9655) if you want support around managing this disease. This late in the season, growers of squash and pumpkins might choose not to put on a protectant spray.  

  • Growers who do not yet have downy in their fields and are hoping to continue picking their cucumbers and cantaloupes are advised to put on a protectant spray (i.e. Zampro or Torrent for conventional growers, Serenade Opti or copper for organic growers)  
  • If you have downy mildew in your cucumber or melon fieldand you wish to keep picking, an application of Orondis Ultra is advised (copper for organic growers).  Conventional growers should rotate to a different FRAC group and spray again 7 days after the first spray as advised by the pesticide label (suggested Torrent as a second application for conventional growers, and another copper spray for organic growers.)  Please also call Rosalie so we can document the spread of this disease. 
  • If you are hoping to keep picking zucchini and watermelons for a few more weeks, a protectant spray is advised as downy mildew spores from Clade I might blow in on Thursday’s storm (i.e. Zampro or Torrent for conventional growers, Serenade Opti or copper for organic growers).  You should rotate to a different FRAC group and spray again 7 days after the first spray as advised by the pesticide label.
  • If you find downy in your squash, pumpkins, watermelons, or zucchini, please contact Rosalie right away.   

Please note that powdery mildew sprays ARE NOT effective against downy mildew.  Downy mildew can very quickly breed fungicide resistance so rotating FRAC groups and following the label closely is key to management.  

If you are currently picking crop, please pay close attention to the PHI listed on the fungicide label.  

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Updates on Cucurbit downy mildew

Tuesday, August 31, 2021

Monday, August 30th, 2021 downy mildew was found in King's County.  Please read the original blog post here.  Downy mildew that infects Cucurbits is specific to Cucurbits - it won't infect onions, grapes, hops, lettuce, spinach, basil, etc.

There is a great Cucurbit Downy Mildew Diagnostic Key, which might help you determine if you have downy in your field.  Please do not hesitate to reach out if you need support in identification and you are a registered farm in Nova Scotia.

So far, downy mildew has only been confirmed here on cucumbers.  The Nova Scotia Vegetable Blog will be updated if that changes.  There are two different host-specific clades of downy mildew.  Clade I mostly infects watermelon, pumpkin, squash, and zucchini.  Clade II mostly infects cucumbers and cantaloupe.  It is possible that we currently only have Clade I in Nova Scotia.  However, there is a storm system blowing in on Thursday/Friday that will certainly bring downy conducive conditions (i.e. prolonged leaf wetness), and perhaps more infections spores of either Clade I or Clade II.  

Cucumber and melon growers should apply protective fungicides as outlined in yesterday's blog post.  Pumpkin, squash, zucchini, and watermelon growers can take a gamble - either apply a protectant as previously mentioned; do nothing and hope there isn't downy that will infect the pumpkin/squash subset; or harvest early.  For growers that do not have established drive rows in their winter squash and pumpkins - especially if they are close to harvest - it may be worth the risk to wait see and thereby avoiding driving over crop to make a fungicide application.  Harvesting early is a good option if the crop is mature and you have curing facilities, especially in light of the forecasted precipitation coming our way on Thursday/Friday.  Downy mildew does not affect fruit, however in the case of cantaloupes, the fruit will be less sweet.  

Cucurbit downy mildew!!!

Monday, August 30, 2021

Fig 1. Heavily infected cucumbers.
ALERT!  Downy mildew has been found in Cucurbit fields throughout Kings County!  

We are lucky here in Nova Scotia, we do not usually get downy mildew in our Cucurbit fields.  This disease is catastrophic - it can take out a field in a matter of days (Fig. 1).  It affects all Cucurbits: melons, watermelons, cucumbers, pumpkins, and squash.  It can very quickly breed fungicide resistance so rotating FRAC groups and following the label closely is key to management.  

Fig. 2. Downy mildew
sporulating on the
underside of a cucumber
leaf.  Sporangia can vary in
colour from light grey to
deep purple with a downy
Monday's cool, drizzly weather has been perfect downy breeding conditions.  Abundant sporangia are produced if humidity is at 100% for 6 hours with temperature between 15-20˚C (Fig. 2). These sporangia are wind blown or splashed onto susceptible host tissue and germinate if leaves are wet for at least 2 hours at 20-25˚C.  Spores can also be carried on your tools, clothes and hands so DO NOT move from infected fields to healthy fields. Spores do not last indefinitely on non-host surfaces, for example exposing spores to sunlight for 4.5 hours kills 63% of the spores.  Spores can survive where there is moisture, for example on wet clothes or farm equipment, but needs living plant tissue to survive for any length of time.  It does not overwinter in our region.  This infection likely blew in from the Southern US.  

Fig. 3a. Early downy infection on
cucumber, leaf surface.

Pale green or yellow spots can be seen on the upper leaf surface as an early sign of infection.  These spots later turn brown and spread.  The spots are typically bound by leaf veins giving it a bit of an angular appearance, especially in cucumbers.  As the lesions spread, the whole leaf will turn brown and look like it's been zapped by frost.  

If downy mildew develops in fields nearby, but not in yours, use weekly rotations of Manzate + Zampro (FRAC group 40, 45) or Manzate +Torrent 400 SC (FRAC Group 21).  If downy mildew is present in your field, apply Phostrol (FRAC Group 33) or Orondis Ultra (FRAC Group 49, 40).  

For organic growers, if you have downy, use copper.  If you don’t have it, Serenade Opti (44), Serifel (BM02– cucumber only) with a liberal dose of prayer.

Fig 3b.  Underside of cucumber leaf.

For all pesticides, be sure to read the label carefully, and follow exactly.  If the label differs from what you read here, always follow the label.  Up-to-date labels can be found here.  

Do you know about Perennia's Pest Management Guides?  Every year we update pest management options for the major crops in Nova Scotia.  A complete listing can be found here (click on Vegetable Crops for the drop down menu).

Fig. 4a. Older lesions of downy
mildew on cucumber leaf surface

Fig 4b. Advanced downy mildew
infection, underside of cucumber leaf.

Fig 5. For contrast, this is powdery
mildew on squash. Powdery mildew
sprays are NOT effective against
downy mildew.


Creating a Balance - Vegetative vs Generative Growth

Wednesday, August 4, 2021

Part 3 - Tampering with Temperature

So far, we have explored the differences between vegetative and generative growth, and the role that water availability and EC play in steering the crop in either direction. Now it is time to explore the impact that temperature and humidity have on these two types of growth.

  • Water availability
  • EC
  • Day/Night temperatures
  • Vapour Pressure Deficit (VPD)
  •  Pruning
  •  Fruit load

Day/Night temps

While we are accustomed to focusing on the temperatures through the day, it is also important to consider the greenhouse temperature at night. With a high night temperature, you are going to see higher rates of respiration, which results in a decreased fruit weight. Allowing the space to cool down over the night is a good strategy to maximize yield. Be careful here though, because too low of a night temperature will result in poor fruit quality.

Not only does a cooler night temperature (compared to the daytime temperature) reduce respiration in your fruit, but it also encourages generative tendencies in the plant. Holding your temperature steady over 24 hours puts the plant into a more vegetative growth pattern.

A good strategy for transitioning from you night temperature to your day temperature, is to allow the space to heat up 1-1.5 hours before sunrise. This is important in maintaining the shelf life of your crop once it has been harvested. Without this warm-up period, you will likely end up with condensation in the production space, which can lead to a variety of issues.

Like irrigation, these highs and lows should be modified on cloudy days – reducing that temperature gap when there is less sunlight will prevent the crop from becoming overly stressed.

Vapour Pressure Deficit (VPD)

Vapour pressure deficit (measured in kPa) compares the amount of moisture in the ambient air, to the amount of moisture in the air surrounding the plant. It is a driving force for transpiration and determines how quickly or slowly the moisture moves out of the plant.

High VPD

  •      low moisture content in the ambient air
  •       big difference in moisture content between the air and the plant
  •      water is rapidly pulled from the plant leaves, putting pressure on the roots to transport more water


  •        high moisture content in the ambient air
  •         small difference in moisture content between the air and the plant
  •         water is not pulled from the plant as quickly
  •        more vegetative plant

How do I know where I stand?

The chart posted below can be used to help visualize the energy relationships of moist air. Based on your VPD reading and the temperature of the grow space, you can determine what the ideal humidity is (and vice versa). By maintaining a VPD in the target zone (shown in green in the chart below), you can rest assured that the air-water relations have been optimized within the plant and prevent encouragement towards vegetative production. Once you start steering towards the red zones on either side, an adjustment should be made to get back into the target zone. Fluctuation in temperature or humidity is okay if the appropriate adjustments are made to keep the system in balance.

Figure 1.  The above chart serves as a guideline for creating an ideal greenhouse environment. Taking regular VPD measurements, in addition to temperature and humidity, will help to keep the system in check. Table was sourced from

Posted by: Talia Plaskett

Garlic harvesting time

Friday, July 30, 2021

Hard neck garlic harvest in Nova Scotia typically happens the first week of August, although with how hot this summer has been (Table 1), some varieties are a bit ahead of schedule.

Table 1. Degree day accumulations as of July 26, 2021.  All data are taken from the Kentville weather station, based on a start date of March 1, and calculated using the single sine method.

Fig. 1. This garlic from mid-July, isn't quite ready to
harvest. Note how the wrapper leaves aren't yet snug
around the cloves.
I have blogged about garlic harvest timing in the past, and if you haven't come across it before, I strongly recommend giving it a read!  The number of green leaves left is a good tell, but if your garlic is super healthy, or super sick, it might not be the best barometer (Fig. 1).  You can find the blog post by typing "garlic" into the search bar on the right of the NS Vegetable Blog, or for direct access, click here.  

By mid-August my car usually smells of garlic from all the samples of unhappy garlic I've collected from growers.  This is often the result of poor post-harvest management.  August in Nova Scotia, when growers are trying to cure their garlic, is often a muggy month, providing poor drying conditions. 

Fig. 2. Relative humidity and temperature.
You NEED good air circulation and ideally low relative humidity (less than 70%) in your curing space otherwise you run the risk of disease running rampant.  If your garlic is taking more than three weeks to cure, it is likely your relative humidity is too high.  There are cheap sensors available from Canadian Tire or Amazon to measure relative humidity and temperature.  If you are serious about growing garlic, I strongly recommend you get one.  Some of the nicer sensors even upload it to a web portal (Fig. 2) so you can check on it from the comfort of the couch. Move the sensor around your drying space to see if you can find any "dead" space with low air movement and higher relative humidity.  Those are the areas where disease is most likely to rear its ugly head.  It is best to try and move some fans to around to get rid of this dead space.

Fig. 3. Unhappy garlic - Penicillium (blue) and
Rhizopus stolonifer (white and black fungus). 

Did you know you could submit samples to 
Perennia's Plant Health Lab?  This service
is often free for registered farms.  Reach out to
 Rosalie Gillis-Madden, 
if you have a vegetable
sample you want to submit to the Plant Health Lab.

It shouldn't need to be said that diseased garlic should not be used for seed.  Advanced growers with smaller plantings sometimes earmark particularly healthy plants in the field before harvest as candidates for seed stock.    To read more about garlic storage, post-harvest diseases, and planting stock considerations, check out Perennia's factsheet.

Fig. 4. Garlic storage, post-harvest
diseases, and planting stock considerations
fact sheet.

Agriculture Weather Station Assistance Program Launched for Nova Scotia

Monday, July 12, 2021

The Nova Scotia Department of Agriculture and Perennia have launched the Weather Station Assistance Program.   

The objective of the Farm Weather Station Program is two-fold: to encourage producers to install weather stations and adopt new technology tools; and fully utilize the data to make proactive management decisions to mitigate the impacts of climate change and adverse weather conditions. 

Funding is open to eligible applicants at 30-70 percent subsidy levels. 

DEADLINES: This program is open until July 30, 2021 



This program is administered by the Nova Scotia Department of Agriculture and is funded under the federal-provincial Canadian Agricultural Partnership Program. 

Perennia will be working with applied applicants to implement the program, including providing the weather station and coordinating the installation. As of the launch of the program, Perennia is completing the competitive bidding process to select the weather station supported under the Program. 

As soon as the model is selected, information will be shared at and via other channels.