One of the things that I’ve spent much of my working career doing is to sort out different problems that occur in different crops. When I moved to Alberta almost 20 years ago, I started working a lot with fruit crops. Since this is the Canadian Prairies, that meant that it was a fairly short list of fruit. The main fruit crop (in terms of total area) is Saskatoon berries.

Much of the time, sorting out issues and problems is often done more as a post-mortem assessment. This is because the symptoms and signs of the problems are often noticed or caught a bit late to do anything other than learn from them and prepare for the future. Most of the disease management strategies for crops are best applied preventatively, meaning that you have to anticipate their arrival by paying attention to the weather, or making some assumptions based on past experiences. For most pests, they have times when they are most active and most vulnerable to being controlled effectively.

For Saskatoon berries, for a long time, there weren’t very many registered pesticides available. Now, there are a range of options. Some of them have application times that are linked to specific bud and bloom development stages, which correspond to the activity of certain pests. Others are applied when disease or pest presence is detected, depending on how the crop is developing.

Years ago, I wanted to know what it meant when the crop was at “green tip stage” versus when it was at “white tip stage”, since that mattered in terms of when certain pests were appearing and when certain pesticides were applied. So, one spring, I asked my neighbour if I could come into his backyard every day or so and take a closeup picture of the developing buds of his Saskatoon berry bush. Over the course of a month or more, I took pictures from when the buds were still dormant, through the buds opening into the flowering stages, to when they reached some of the immature fruit stages.

It is important to note that the speed that plants move through these stages can vary year to year, with location, climatic conditions, and varieties having an effect. The pest occurrences that are listed with each stage can also vary for the same reasons.

Products like dormant horticultural/mineral oil sprays are often applied now to control things like Saskatoon bud moth. You have to be careful with what you use after oils, since some products will negatively interact with them up to a month afterwards.

This is a stage where you could still target the overwintering pests that are exposed.

This is the stage when you would be targeting early pests that feed on the buds (such as Tarnished Plant Bug adults and Saskatoon bud moths). This is usually the first insecticide application stage.

At this stage, you could still target those early bud-feeding pests.

You could still target early bud-feeders, but it is getting late, so damage might already be done.

This is usually when most of the first fungicide applications that will protect the flowers and fruit occur, since this corresponds to when some of the diseases start to be active. You might also see some of the leaf-rolling insects start to show up, so some insecticides are registered for this time.

At this stage, you could apply some of the early, pre-flowering treatments to control some of the insect pests, or some of the preventative fungicide treatments. This is also the early edge of some of the suppression treatments for diseases like fireblight or controls for powdery mildew.

This is when the insecticides targeting the insects that attack flowers and flowering parts are applied. They are applied early, to try and avoid any active pollinators. At this stage, you would also be applying the biological controls that compete with the fireblight pathogen.

At this stage, you might be applying the last of the biological protectants or starting to think about putting on fruit protective fungicides. This is also when most of the main fungicides go on to protect the early fruit for a period of time.

This is the stage when the last of the main insecticides are being applied, targeting the adults of things like Apple curculio, as they become most active and before they can lay their eggs inside the fruit. You might also be protecting plants from powdery mildew, or other diseases. This is typically when most of the longer lasting fungicides are applied, as they have longer pre-harvest intervals (e.g., 38 days)

At this stage, you will be considering sprays for various diseases, geared to protecting the new fruit. Any products applied will have shorter pre-harvest intervals but may have longer re-entry intervals for hand harvesting.

At this stage, if the weather conditions are such that the disease risk is high, some short pre-harvest interval fungicides might be applied to protect the fruit.

At this point, or just after harvest, you might also be applying products to the soil that will suppress root feeding insects (e.g., Woolly Elm Aphids)

There are also products that can applied at different points, based on trapping and monitoring activities, or disease surveillance.