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Monday, November 18, 2024
Hurricane Preparation for Greenhouses
Thursday, August 15, 2024
We have officially entered the time of year where hurricanes and tropical storms are active, and pose a threat to Atlantic Canada. It is important to stay informed on the timing, and track, of all monitored storms in order to give yourself as much time as possible to come up with a plan of action and prepare the farm.
Check out Environment Canada's Hurricane Track for updated information on all monitored storms. For those of you who haven't been following yet, Hurricane Ernesto looks to be headed towards us. It is still quite early, and storms often change direction to avoid missing us entirely, but it is worth staying on top of the forecast. Even if we don't get hit with the full brunt of the storm, Beryl showed just how much of an impact that the surrounding weather system can have.
Crops that are most vulnerable to weather extremes can be prioritized in order to save as much of the crop as possible. Things like cucurbits and field tomatoes are prone to splitting after heavy rain, so would fall high on the list of things to harvest before things get going. Consider postponing the seeding of new plantings or cover crops in the days leading up to a significant storm. Wind and pounding rain can cause erosion and flooding, which easily dislodges tender seedlings, or washes away the seed all together.
Preparing Your Greenhouses
Climate change brings both a higher frequency and increased intensity of extreme weather events. It is important to think about how high tunnel structures can best be built and modified to endure the extremes. The information below is a fantastic summary of experiences shared by the growers of the Vermont Vegetable and Berry Growers Association (VVBGA). Individual grower comments and references for more information are provided following the summary.
To access this resource, click here
If there is an option to remove the plastic from a structure, the chance of structural damage can be significantly reduced. While this would expose the crops beneath, and could result in crop damage and loss, the main infrastructure can be saved. It is a difficult decision to make, but ultimately compare the value of the crop to the value of the structure itself when weighing the options. For crops that are close to being done for the season, a slightly earlier end to the season could be less detrimental compared to the loss of a structure.
If removing the plastic isn’t an option, make sure everything is sealed up as much as possible to prevent the wind from tearing things loose. Latch and brace doors and vents, re-enforce end walls, and tie the sides of tunnels down tight. Most structures will have a rating for maximum wind speeds they can withstand. Take into consideration any shelter/exposure provided by the topography of your farm as well as the up to date weather forecast to help make an informed decision.
It is also advised to unplug electrical equipment where possible to prevent a surge once power returns, and ensure that drainage systems are cleared and ready for large volumes of water. Make sure that the area surrounding the greenhouse is clear of items that could be picked up by the wind, and that any weak/old overhanging tree branches have been removed.
If you have a generator, make sure you have plenty of fuel and that it’s in an accessible place. If you don’t have a generator and require power for your watering system, make sure to give the crop a good water before things get going. Its always a good idea to try and have some water set aside in barrels in case of emergency.
The Aftermath
Nova Scotia has been affected by extended power outages caused by storms, major floods and wildfires. Boil orders and potential water contamination caused by drought, floods and fires have also impacted the province. Some consumers, food producers and processors or packers have even been affected by supplier actioned recalls due to the suppliers’ contaminated ingredients purchased to make their products. Due to recent events and inquiries for guidance and assistance on emergency response, Perennia Food and Agriculture Corporation has pulled together reputable links and guidance for the reader to reference should they be affected.
To access this resource, click here.
Besides damage by wind and heavy rains, disease issues can be a big consideration after a storm event. Heavy rain can splash fungal spore or bacteria-containing soils around, facilitating the spread of infection. Crop protectant products may be washed away, leaving the plants vulnerable until they can be sprayed again, if at all.
Wind and rain may cause physical damage to the plants themselves, causing them stress and areas of damage where infection can move in. High winds sweeping up the coast may even carry insects from elsewhere, resulting in a flush of insect pressure that would otherwise be unexpected. It is important to scout your remaining crops as soon as possible after a storm has passed so that there is opportunity to mitigate any pest pressure brought on by or worsened by the weather.
A few diseases of note: downy mildew and late blight are documented across the eastern United States. Diseases are easily blown in from the south through these systems, so keep an eye on these symptoms specifically and look into preventative spray plans where possible. High botrytis pressure typically follows these systems as well, so make sure you have a plan in place as to how you can protect your crop and reduce the impact.
-Talia
August Newsletter
Sunday, August 4, 2024
Upcoming Events/Perennia Updates
- TunnelTalk (virtual Series)
- August 14 - Expert Panel Discusses Greenhouse Structures
- September 4 - Three Ways Around Winter Spinach Production (registration up soon)
- October 9 - Water Quality for Protected Crops (registration up soon)
- Understanding Alternative Nutrient Amendments (Virtual Series)
- August 6 - Let's Discuss Bio-Solids
- OFCAF Field Day Save the Date
- September 18
- OFCAF Split N and Summer Cover Crop Demo Save the Date (Tunnel systems)
- September 25
Weather Updates
Seasonal Considerations: Nutrient Deficiencies
Nitrogen deficiency:
Plant-available nitrogen can easily move through the soil profile if it is not taken up by the plant. Leaching is especially common following large amounts of irrigation/precipitation in a short time. Continuous small amounts of precipitation/irrigation cause the same thing, but to a lesser degree.
Nitrogen deficiency is typically observed as yellowing of the lower leaves of the plant, but can also look like slow/stunted plant growth. Nitrogen is mobile through the plant, so the top parts usually remain green unless we are looking at a severe case of deficiency where everything has now turned yellow.
- If the plant is generally a pale green colour, you might be looking at a magnesium deficiency. Supplementing N and Mg together should clear that up pretty quickly if that is the culprit.
- If the leaves have dark green veins with yellow between them, this is an iron deficiency - nitrogen supplements will not help.
Overuse/careless application of nitrogen is costly, not only on your wallets, but on the environment as well! For those who are supplementing nitrogen through their irrigation lines, make sure to give the plants a good water before running your fertilizer solution through. This way the plants will be sufficiently watered, and you won't accidently be washing your freshly-fertigated solution deep into the soil profile before the plants have a chance to take it up. Short, shallow stints of water are always going to be better than long, deep applications for nutrient delivery to target zones and optimizing the amount taken up.
Magnesium Deficiency:
This can present in a couple of ways on the bottom leaves of the plant:
- Stiff, brittle leaves that are cupping upwards
- Interveinal chlorosis/purpling
Potassium Deficiency:
The most common symptom of potassium deficiencies are:
- Yellow shoulders in tomato fruits
- Uneven ripening
If you are unsure about what your plant needs in season, or want to get to the bottom of some odd discolouration and growth habits, consider a tissue test! We have a good sense of what is present in the soil from our recent soil test, but that doesn't mean that it is plant available! Tissue test results give us a sense of what is actually being taken up by the plant, and we can make decisions based on that result. Things like potassium and magnesium can be out-competed by calcium even though they appear abundant in the soil test, so it never hurts to double check as we try to understand what's happening with the crop..
Additional Resources:
- Perennia's Nutrient Deficiency Guide
- Perennia's Plant Health Lab is always available to give an official diagnosis on the weird and wacky
- NSDA Analytical Lab (Tissue Testing)
Production Tidbits: Winter Cash/Cover Crops
Light becomes the limiting factor for growth around the end of October in Nova Scotia, meaning that unless we are supplementing with artificial lights, we are likely going to see a drop off in the amount of biomass produced per unit time. Maximizing the amount of time our crops have with optimal light will translate to more above-ground biomass produced compared to those that are exposed for shorter amounts of time.
For cash crops, consider the varieties you've worked with from 2023-2024. Did we like the performance? Were some more susceptible to pests, disease, nutrient or temperature stress compared to others? New disease pressures in your summer crops could have an impact on the success of the winter batch, so keep an eye out for more resistant/tolerant varieties to help reduce the impact on your next batch.
For cover crops, lets think about what your goals are - do we want to build organic matter? Generate nitrogen for the next season's cash crop? Do we want something that will survive the winter? Maybe our biggest headache was some disease/pest pressure, and there are some cover crops that are effective at reducing pest populations! This should help guide decisions on what should be planted so we can work on improving production overall.
2) Make sure we source/order our seed early! Nothing worse than putting together our dream winter gardens and not being able to get exactly what we want
3) Planting density! Did we see more fungal disease in recent years? Or too many empty spots in our cover crop seeding? Playing around with planting density is a great way to increase the 'bang for your buck' without having to make drastic changes to your day to day plant production
4) How are we going to irrigate our winter crop? Both cash crops and cover crops require water to get going and growing, so best to come up with a plan beforehand on how best to get water out to winter spaces.
5)PEST CONTROL. Now I wish I had some silver bullet beneficials that are going to keep our plants happy all winter long but that is not the case. Make sure that you have your pest populations under control through your summer season, to help reduce the pressure that comes through on your next batch of plants. It may be easy to let things go as we get closer to ripping plants out for the season, but we are only making our lives harder for the next crop to come by doing so. Your extension specialist would be more than happy to discuss your options with you!
Feature Pest/Disease: Late Blight
Late blight (caused by Phytophthora infestans) is a highly damaging disease of tomatoes and potatoes, which infects leaves, stems, tomato fruits, and potato tubers. In ideal conditions late blight can spread rapidly and result in complete crop loss if untreated. Initial symptoms usually appear as small, light to dark green, water-soaked lesions on the leaves, which turn grey to tan and produce grey spores on the underside of the leaves. Stem and other parts of the plant then become infected and spores can then spread the disease to adjacent plants or be carried on the wind to other fields. Disease development is favoured by cool wet conditions and generally appears later in the season
Late blight is an obligate parasite, meaning that it cannot survive outside of it’s host for extended periods. Because of this late blight generally does not over winter in Nova Scotia or other cold climates regions where the disease and susceptible plants are killed by freezing temperatures. Instead, the disease moves north annually on wind currents and storms from the southern United States where tomatoes are grown year-round. The first late blight infections in Canada and the northeastern United States usually don’t occur until later in the season. However, late blight can overwinter in infected potato tubers that are left in the field or cull piles if they don’t freeze or decompose completely, which can also cause out breaks earlier in the season.
In early July late blight was found in Southern Ontario in potatoes and tomatoes (https://extension.psu.edu/2024-late-blight-status map#:~:text=The%20first%20week%20of%20July,less%20so%20on%20potato%20foliage. ), outbreaks in US and Canada can be tracked here(Home · PlantAid (plant-aid.org)). The map can give an indication of when infection could be likely, but scouting is critical to identify when late blight occurs in a crop so that management can be implemented in a timely manner. There are several organic and conventional controls for late blight, in all cases they need to be used before or during early stages of infections to be effective. Please refer to the PMRA pesticide label search (https://pr-rp.hc-sc.gc.ca/ls-re/index-eng.php) for up-to-date labels. If you suspect you have late blight please contact a Perennia Specialist.
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