As the growing season gets really rolling, growers will start to see signs of issues that are starting to develop. I have discussed some of the generally symptoms and signs that are might raise flags (See Hort Morsels Blog – Early Warning Signs). However, here are some pests and diseases that you might have already encountered, or that I have run across in my recent travels across the province, or that you should be watching for right away. This is not an exhaustive list, of course, but it is enough to get you started. Where possible, I have linked to a more detailed bit of information on this website (more to come).
Why do symptoms appear?
Shifts and changes in localized conditions in the fields can potentially trigger the appearance of plant health symptoms, either through the stress overcoming the plant’s resistance to the pest, or by creating conditions that favour the development of the pest.
Common early season insect pests
There are several pests that munch, chew and tunnel their way through the annual plants in our lives. In some cases, it is challenging to say definitively that one pest is the sole culprit, but it bears consideration.
Cabbage (and other root) maggots
I cannot think of a year in my career (to this point) where I did not have at least one (or a dozen) questions about controlling root maggots of some sort. The respective species are the bane of all Cole crops, and can do some major damage on bulb vegetables.
Learn more about them – Cabbage Maggots
Photo by: Mary Ann Hansen, Virginia Polytechnic Institute and State University, Bugwood.org
Flea Beetles
There are different types of flea beetles out there, but we tend to notice the one that affects cruciferous plants, since we grow so many of them. They wreak havoc on the seedlings and smaller plants but will feed on larger plants to great effect. They leap away when they are disturbed, which can result in an upsetting rattling and shaking of plants as you move near them.
Learn more about them – Crucifer Flea Beetles
Photo by: Robert Spencer
Cutworms
Cutworms tend to appear a bit earlier in the season, performing destructive magic tricks, making seedlings disappear from the garden. There are a few different types, but they are universally committed to the letter C when disturbed and they lurk under the soil surface, waiting for dark.
Learn a bit more about them – Cutworms
Photo by: Robert Spencer
Tarnished Plant Bugs
As strawberries come into full season, with both blooms and blossoms present, it is challenging to control these pests, however you will see the product of their labour throughout the season, as waves arrive from other crops. You scout for the nymphs in the blossoms, from the time that they open, throughout the season.
Here is a bit more about these critters (Tarnished Plant Bugs) and a video that discusses everything from identification to scouting (Horticulture Tips: Tarnished Plant Bug)
Photo by: Robert Spencer
Spider Mites
As the temperatures climb, and as canopies fill out, you might notice the signs of spider mites. They are particularly prevalent in hot, dry conditions, or in protected areas. I most often see them in things like raspberries and strawberries, but they are not picky and will show up in other areas. Watch for a general fading of colour in the foliage, the presence of webbing and a dusty appearance on the underside of leaves. A close look will show “moving sand”, which is actually the mites moving.
Photo by: Robert Spencer
Aphids
There are many, many different types of aphids that will make an appearance throughout the growing season. While consistent in shape, general features, and demeanor and habits, they differ in colour and specific features (if you look closely). Their impact can also vary, with some being serious vectors (carriers) of viruses.
Learn a bit more about different types and try your hand at ID – Aphid species
If videos are more to your taste, here is a video with some of the same sort of information – Horticulture Tips – Aphids
Photo by: Robert Spencer
Common early season diseases (or ones that I saw recently)
There are several diseases that show up and sicken our plants. Some of them like to gang up and hang out with their friends.
Seedling rots / Damping off
This is the “teenage gang” of the disease world. If conditions are cool/cold and wet, you will often find Pythium, Rhizoctonia and Fusarium making a nuisance of themselves. You will find that plants will gradually decline in vigour and health, and then collapse or droop. A tug on the plant reveals an absence of roots.
Photo by: Robert Spencer
Fireblight
Fireblight is an unwelcome and destructive visitor, often arriving on the wings (or body parts) of the pollinators that visit the flowers. Abundant moisture and moderate temperatures favour this bacterial disease.
Learn more about it – Fireblight
Photo by: Robert Spencer
Saskatoon berry / Juniper Rust
I noticed a little bit of this out in the orchards this past couple of weeks, or it was reported to me. It can be quite dramatic in appearance, with bright orange blazes of colour and weird horns and swellings on leaves and fruit.
Learn more about it – Saskatoon berry / Juniper Rust
If videos with calm, level narration are your thing, check out Horticulture Tips – Saskatoon Juniper Rust
Photo by: Robert Spencer
Common Leaf Spot (of strawberry)
This disease of strawberry can be confused with other diseases that it resembles (loosely), but the cool, overly wet conditions that have been present in most of Alberta for the past several weeks favour this disease. It is characterized by small purplish lesions with a lighter centre. The symptoms can vary a bit between cultivars.
Photo by: Robert Spencer
Botrytis Grey Mould
Botrytis is that weird cousin that shows up basically everywhere. It has an extremely wide host range and causes rots and disease in most fruits and vegetables. The common denominator is the grey mould (made up of a gazillion spores) and a watery rot that progresses across the tissues. At first, it often shows up in older, overripe fruit, but it can develop on green, immature product if conditions are suitable. The moisture that we have experienced recently is perfect for this pathogen.
Photo by: Robert Spencer
Powdery Mildew
When you get stagnant air and somewhat higher levels of humidity, you often will see powdery mildew appear. We more often see it appear as the season progresses, but in some specific areas (e.g. high tunnels), we might see it sooner. Despite their extremely common name and common appearance, powdery mildews are highly specific to their host crop. We often see powdery mildew in peas and cucurbits (cucumbers, squash, etc.), but it will also appear in strawberries and other crops.
Learn more about it in this handy video – Horticulture Tips – Powdery Mildew
Photo by: Robert Spencer