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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