Problems in the garden

Abnormalities in your plant's growth are typically caused by diseases, disorders, weeds or insects. Disorders are abnormalities usually caused by environmental factors such as nutrient availability or temperature. Examples include chlorosis or frost cracking. Diseases are abnormalities caused by microorganisms or other pathogens invading your plant. Examples include black knot or grey mould (botrytis). You will find insects and weeds on their own pages since they're relatively easy to tell apart. As many non-professionals will not know whether their problem is a disease or a disorder, we've placed all of these types of issues on the same page.

It's important to remember that all outdoor plants will be exposed to multiple diseases, disorders and insects, but most of the time only some plants will be damaged by them. Which plants get damaged? Typically it's the plants that are already stressed by not having enough light or consistent water.

Check the tabs here for useful diagnostic questions and support documents. See below for specific advice on the most frequent issues in our growing area, then check out the rest of the Gardenline Online website for the typical issues that face most gardeners on the Canadian Prairies and Northern Canada. All of our advice is pesticide free.

If you want to keep your growing issues lower, make sure the basic needs of the plant are met so your plant can defend itself from common problems. Most plants need the upper range of sun on their growing tag (ie. if it says full to partial sun, it probably is most healthy and resilient in full sun). In our climate, mulch is likely a good choice for most situations. Of course, while this is solid basic advice, it won't help prevent every problem you may encounter.

Plant Diagnostics

There are many issues that a plant can have. You will find insects and weeds on their own pages since they're relatively easy to tell apart. As many non-professionals will not know whether their problem is a disease or a disorder, we've placed all of these types of issues together. What is the difference? Disorders occur when plants grow in unhealthy or unexpected ways and are usually due to the growing environment or to chance. Diseases are usually caused by an environmental pathogen. A good example is blossom end rot in tomatoes. The browning on the end of the tomato fruit is caused, fundamentally, by inconsistent water. This is a disorder. The tomato would have been healthy had water been available consistently and, if the gardener waters consistently, future tomatoes will be healthy. However, once a plant has blossom end rot, this lesion may become infected with local pathogens and "rot", which is considered a plant disease. While unlikely in this case, it's possible that this pathogen could spread to other plants in the garden. This is an example of a plant disease.

Please note that we also have online, on demand workshops to teach home gardeners about the plant diagnostic process as well as classes on diseases, disorders, insects and weeds.

So, you have a plant with a problem and want to know how to fix it.
Diagnostics is not easy, in fact, it can be downright frustrating. Diagnostics usually involves asking a lot of questions to find the cause of the problem you're seeing on your plant.
 
There are three possible causes of plant problems: living factors like insects and diseases, and non-living factors like disorders which cause plants to become stressed. Insects and diseases seldom attack healthy plants. Stressed plants more likely to get insects and diseases. Insects or diseases are easier to spot and are often wrongly blamed for the entire problem.
 
When you see an obvious problem like an insect or disease, it’s important to look beyond the obvious symptoms. All plants have different needs, so start with knowing the name of the plant and understanding its basic needs for light, air, water, space and soil. Is this the right plant for the right place? Are there other factors like weather, pollution, herbicide or chemical damage, improper pruning, physical damage, improper planting, site not suitable to plant needs, too much fertilizer, soil compaction, salinity, drought or flooding that may be contributing to plant stress?  Very often correcting a disease or insect problem also involves correcting the underlying cause.

Now that you're ready to begin the diagnostic process, here are some questions to get you started on your investigation.

Basics

  • What kind of plant is it?
  • How old is it?
  • Has it always been healthy?
  • Are there other examples of this plant nearby? How are they doing?

Abiotic (non-living) considerations:

  • Where do you live?
  • What was last winter like?
  • What is your soil like?
  • Is road salt or sidewalk salt an issue?
  • Do you water it?
  • Was there any flooding in the area? Are there any sloughs nearby?
  • What is around or near the tree/shrub?
    • Sidewalk, driveway, road, house
    • Garden, grass
    • Anything damage the bark?
      • Lawnmower, trimmer
      • Animals: rabbits, mice, deer
      • Ropes, ties, hammocks, swings

Leaf related:

  • Examine leaves in several regions including new leaves at the end of the branches as well as older leaves more interior to the plant. Depending on the plant, not all leaves on the same plant will be shaped or coloured identically even on healthy plants. Your initial examination is looking for leaves that are obviously different from a healthy leaf.
  • Are the leaves an unusual colour? Note that it is normal for most plants to "drop" leaves that are no longer productive, typically older leaves that are now shaded by new growth. Some plants, such as Schubert chokecherries normally start out green and mature into a black colour. Here, we are looking for abnormal colouring such as:
    • a speckling of colour across the leaf
    • white lines along the leaf
    • black spots, tips, or regions
    • browning (often associated with leaf dryness)
    • overall bleaching of the leaf to a yellow or white
    • the leaf veins look significantly darker than the rest of the leaf
  • Is there any wrinkling, rolling, pinching or cupping?
  • Are there holes in the leaves? Are they more rips, punctures, or missing pieces? Do they have jagged or smooth edges?

Planting related:

  • When was it planted? What time of year?
  • Container-grown, balled and burlapped, or seeded into place?
  • How big was the plant when it was planted? What condition was it in?
  • What did the roots look like?
  • Describe how you planted it? How big was the hole?
  • Did you amend the soil?
  • Did you add any mycorrhizae or fertilizer?
  • How often/how much was it watered after planting?
  • Was the tree staked? If so, for how long?
  • Where is the trunk flare located in relation to the soil level?
  • Is the plant mulched?

Other useful websites

Need more help? The tabs in this section sort our recommendations for reliable websites. These are all outside of the University of Saskatchewan, but are from reputable organizations.

Kansas State University Turfgrass Problem Solver - not all issues listed are relevant here but the majority are

Current issues and solutions on Facebook

Our Gardening at the U of S Facebook page post multiple times a week on topics that are important, right now, to your garden. If you are having an issue with an insect, disease, or plant odds are good other people are too. In addition to timely information, we also keep you up to date on new research, coming events, upcoming courses, and hort job opportunities. Check us out to see if we have something posted to help you!

Gardenline

Gardenline is a free help service offered by the Plant Sciences department at USask from May to September. We specialize in educating home gardeners about all aspects of home gardening (especially growing food) on the Canadian prairies and far north. Click on the "Need Help? Find it fast." tab to access Gardenline.