Invitation to Perennia's Annual General Meeting

Tuesday, June 15, 2021



Join us Thursday, June 24th at 2:00 PM (AST) for Perennia’s 2020/2021 Virtual Annual General Meeting. Click  here to register!

Creating a Balance : Vegetative vs Generative Growth

Monday, June 14, 2021

Part 2 - It's All in Your Water

There are many factors that play a role in managing vegetative and generative growth, and it is important to consider a well-rounded approach when attempting to swing the scales. Keeping a balanced growing environment is important for a highly productive plant and changing one thing and nothing else will end up causing more harm than good.

In part 1 of this mini-series, we addressed the need for vegetative growth to have a high yielding crop. Vegetative action is required early in the crop cycle so the plants can establish themselves. By creating this strong base, the plant will be able to support a highly productive generative state later on.

The generative growth phase focuses on managing plant productivity. It is achieved through strategic stress induction in your plants. These minor stresses are going to push the plant to divert resources to reproductive organs (fruits), while ensuring that all other plant processes can be maintained. The key word here is minor – pushing the plant too far is not going to have the response you are looking for.

How Do I Manipulate the Plant?

A few of the major contributing factors to vegetative and generative growth are listed here below. We will address the impact that each factor has on crop steering.

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

Water Availability

Watering frequency, duration and timing plays a role in pushing the plant towards a more vegetative or generative state.

In vegetative action, water is readily available for the plant when it needs it. The plant does not have to work hard to uptake water and will readily create new above- and below-ground biomass. As roots and leaves are being produced, the plant is preparing for full-blown production. Higher water content in the substrate is achieved through small, frequent irrigation events throughout the day.

Once it is time to switch to generative growth, these watering events become longer and more infrequent. As water becomes less available, less energy is put towards the production of root and shoot material, and more will be diverted to fruit production. The plant will now have to actively seek water compared to it being readily available in the vegetative stage.

Figure 1. Depicted here is the general irrigation strategy for substrate-grown greenhouse crops (ex. Tomato). Water content (WC) is depicted in green. While the timing and frequency of watering for generative and vegetative phases will vary, the general concept applies. As the day ramps up, you slowly increase the amount of water you deliver to the crop. After you achieve first run-off, you can start hitting the crop with water at regular intervals (determined, in part, by the weather that day). As the end of the day approaches, irrigation stops all together. Photo credit: Greenhouse Canada, June 2010 (https://www.greenhousecanada.com/september-2010-2418/)

While the daytime irrigation strategy is important in crop steering, you must also consider what is happening through the night. The length of the dry-down period of your growing media will help to tip the scales towards vegetative or generative tendencies. A short dry-down period (usually achieved by scheduling the last irrigation event of the day 1-2 hours before sunset) encourages vegetative growth. A longer dry-down period (which would have the last irrigation event happening earlier in the day) will encourage generative tendencies.

EC Measurement

The electrical conductivity (EC) of your fertilizer solution is important to consider when encouraging vegetative or generative action. EC is an indication of the salt content in the solution and will therefore impact water availability to the plant. A higher EC value means a higher salt content, and the harder the plant must work to take up water. As the plant works harder to take up water, less resources will be sent to vegetative growth (leaves, roots) and more will be sent to the generative tissue.

Here is a rough guideline of where your target EC should be, based on the crop stage:

Plant Stage

Target EC

Germination (vegetative)

0 - 1

Plant raising (vegetative)

2.5 – 3

Harvesting (generative)

2.75 – 3.5*

Full harvest (generative)

2.75 – 4*

*Should be watering with an EC of around 3, but you will see a higher substrate EC as the salts accumulate in the grow media

Understanding how your watering habits sway the crop in one direction or the other is a good starting point. Irrigation is something that all protected producers have control over, and it is important to see that watering plays a huge role in plant phenology and overall production capacity.

Creating a system that encourages maximum production capacity is in everyone’s best interest, and it is extremely important that all factors are addressed when trying to push for a more generative crop. Adjusting the watering and EC alone are not going to be enough to hit the target yield. All plant processes are intertwined and should be carefully considered whenever adjustments are made.

Stay tuned for our next post on vegetative vs generative growth, which looks at the role of temperature and humidity in crop steering.


Posted by: Talia Plaskett

Pilot Program for Nation-Wide Monitoring of European Corn Borer

Thursday, June 10, 2021

 European Corn Borer (ECB; Ostrinia nubilalis) has been an important pest of corn in eastern Canada for nearly a century now. It is becoming apparent that ECB is a generalist feeder, and has a wide range of hosts (ex. Hops, tomatoes, peppers, etc.).

The symptoms of ECB infestation will vary depending on the crop. The classic symptoms of corn see larvae migrating their way down the ear, chewing and burrowing as they go, rendering it unsaleable. In vine crops (pepper, tomato, eggplant), larvae can enter the stem and cause wilting or death. They are also attracted to the fruit, and will reduce your marketable yield.  For more information on the life stages of ECB, the impact it has on a handful of crops, monitoring and management, check out our factsheet!


Figure 1. An image of a ECB larvae that is taking refuge within the stem of a cannabis plant in Nova Scotia. Photo credit: Alex Gillis

With a recent confirmation of ECB resistance to Cry1F Bt corn in Nova Scotia, there is an increased need to monitor pest distribution across Canada. The Surveillance Working Group of the Canadian Plant Health Council has developed a harmonized monitoring protocol for ECB. This can be used to report the sightings of eggs, larvae, or any crop damage observed across Canada. It is encouraged that you try the harmonized monitoring protocol and report the data from your production using the free Survey123 app (available for both desktop and mobile devices):

  • Early to Mid-Season ECB Survey (Before July) - https://arcg.is/0qCCHH
  • Later Season ECB Survey (July to Pre-Harvest) - https://arcg.is/fSODf

You can log your information without creating a profile, otherwise a hard copy version is also available. 

Why should you care?

Real-time reporting may help estimate the risk of outbreaks in your region, and target the ideal window for scouting and management. At the end of the growing season, maps illustrating the results of the monitoring program will be made available on the 'Great Lakes and Maritimes Pest Monitoring Network', and the 'Prairie Pest Monitoring Network' websites, among others. 

Please feel free to contact Tracey Baute (OMAFRA), Meghan Vankosky (AAFC-Saskatchewan), John Gavloski (Manitoba Agriculture and Resource Development), James Tansey (Saskatchewan Ministry of Agriculture) or Brigitte Duval (MAPAQ) if you have questions about this pilot project.

Creating a Balance: Vegetative vs Generative Growth

Friday, May 28, 2021

Part 1 - Setting the stage 

Most greenhouse vegetable producers will have come across vegetative versus generative growth in their vine crops (tomato, pepper, cucumber). Over the next few weeks, we will be exploring the differences between the two types of growth, what they look like, and how we can manipulate the plants to encourage one form of growth over the other. This information will be focused on tomato production, but it is important to note that the same concepts apply to other crops.

Vegetative growth is characterized by:

  • Thick stems
  • Lots of leaves and suckers
    •  Leaves are long and can be twisted/curled
  • Dense growing tip
    • High density of leaves
  • Small fruit
  • Elongated fruit truss

The plant is putting most of its energy towards the production of plant material. While leaves are important for photosynthesis, tipping the balance towards a more vegetative state does not leave enough energy being diverted towards fruit production. The size and quality of the fruit coming off a vegetative plant will be significantly less than what you would want.




Figure 1. An image of an overly vegetative tomato plant. Notice the thickness of the stem, the high density of plant material, and the curling of the leaves. Photo credit: Government of Alberta, Tomato plant propagation in commercial greenhouse tomato production (https://www.alberta.ca/tomato-plant-propagation-in-commercial-greenhouse-tomato-production.aspx)


Generative growth is characterized by:

  •       Thin stems
  •       Fewer leaves, typically shorter in length
  •       Good sized fruit
  •       Slight purple tinge to the growing tip

These features indicate that the plant is putting most of its resources towards fruit production. While we want to see generative growth, it is possible to tip the balance too far. A plant that is overly generative, will not have the leaf resources available to power plant growth. Overly thin stems with few leaves will not be able to support a high fruit load, and the resulting fruit will not be of market quality.


 


Figure 2. A tomato plant that is growing generatively. Notice that the stem is significantly thinner here compared to Figure 1. The leaves are much less densely packed, and the leaves are not curling excessively. Photo credit: Talia Plaskett, Perennia.

Production of greenhouse crops requires both types of growth for optimum production. The act of rooting after transplant is considered vegetative. You want to encourage the plant to establish a good strong base in the growing media, so that it can support the plant through the growing season, and push for high yields. After a certain point, you want to start pushing the plants to a more generative state. This will encourage more fruit, and of a higher quality as well.

How do I know where I stand?

Designate one or more areas within the greenhouse as being your primary monitoring spot. This area should be representative of the growing conditions in that space – many growers will choose the centre of the tunnel/greenhouse, and pair this with the location where they are collecting information on drain EC/pH and slab weight. Each production space should be considered its own entity, as temperature, humidity, air circulation etc. will vary between bays despite our best efforts.

Within this monitoring block, a series of measurements should be taken weekly. Things like stem width (measured below the youngest flower cluster with an open flower), internode length, leaf length, weekly growth, and number of leaves/clusters will let you know how the crop is doing. Keeping this information on record will help you get an idea of how your interventions paid off, and generally how the crop is doing. These measurements can also be used to forecast future yields and therefore what will be available for retail.

Weighing the Options on Ground Cover

Tuesday, May 25, 2021

 There are many benefits to incorporating ground cover into your growing space. This woven or plastic material can drastically reduce weed pressure, presence of mud in the grow space, and protect your produce from soil particles. It acts as a barrier to pests and disease lingering on the surface of the ground and will impact the climate in your growing space.

Ground cover comes in different colours and source materials. Check out our new fact sheet (https://www.perennia.ca/wp-content/uploads/2021/03/Fact-Sheet-Ground-Cover-final.pdf) to explore the options available and decide which will be best suited for your space!



Posted by: Talia Plaskett

Things are Heating Up!

Wednesday, May 19, 2021

Thanks to our friends at AAFC, we have the capability to compare our current weather data to that of the past! This helps us understand where we are in the grand scheme of things, and assists in the planning and execution of outdoor planting and field trials. 


Based on the weather measured from March 1st to May 17th 2021, we are right on track with what was observed in 2006 and 2017 for number of days above 5°C. As we amp it up to base 10 degree days, we see we are tracking similar to 2006, 2009, 2014 and 2018.




Despite a relatively dry winter/early spring, we have managed to catch up to the 10 year average the last few weeks! The red line on the graph tracks the cumulative precipitation of 2021, compared to that captured in previous years. Note that 2020 was tracking relatively similar to what we observed earlier this year. Hopefully things continue to progress on the wetter side of things and ease the stress surrounding hot dry growing seasons!


It is important to note that these values were collected at the Kentville Research Station - microclimates DO exist throughout the valley, as well as across province, so this is merely a guideline! For more site-specific information, consider installing your own weather monitoring station!


Posted by: Talia Plaskett

Let's Put Our Irrigation to Work!

Tuesday, May 11, 2021

 As we wrapped up this winter’s Getting into the Weeds seminar series, we want to thank you for attending our sessions 

As the season quickly moves along, we wanted to remind you to reference the irrigation information we shared with you over the winter.  You learned about everything from the water-soil relationship to the basics of setting up an irrigation system and how irrigation can influence crop disease development. 

 

So as you are setting out that irrigation pipe or considering your irrigation plan for this year, go back and check out these helpful videos available at Perennia’s YouTube channel. You can also reach out to one of our many crop specialists for advice on your water management.  

 

Have a great season!