Gardening is a belief in the future. You plant, do your best to provide a good environment, cross your fingers, and hope nature will support your view of how the space should look. With living plants as the medium, the process can be tricky. Many plants will flourish in the locations you’ve chosen for them, but others will become diseased and a few may die sooner than expected.
When I look at the river birch in my garden, a heat-resistant cultivar with three beautifully exfoliating trunks, I think, everything is good. After four years, the birch has almost tripled in height and caliper, settling in to the site I selected with gusto. A success. But then I sense a problem elsewhere, something that catches my attention and is not right. The Nellie Stevens hollies that once formed a glossy dark green backdrop appear dull and covered in soot. And is it my imagination, or do the leaves on the American hornbeam look more yellow than green, a bit too chartreuse for this time of year?
What’s wrong with my plants, and just as importantly, how did I miss these problems that most likely have been developing over time?
Somewhere along the way I fell short on observation, a skill essential to gardening. It’s easy to get distracted, especially by plants that reward your efforts by thriving—my birch for example—and grab attention from less optimal developments in the garden. But if your observational radar always is on, you have a good chance of catching problems as they develop.
When you do find a problem, it’s important to slow down and analyze the situation. A plant in trouble does not necessarily require chemical treatment or removal; solutions may be more basic, especially if you’re willing to tolerate some pests and plant damage. Cutting out affected branches helped combat the cottony camellia scale that led to black sooty mold on my hollies. One year later, with improved air circulation and light, most of the leaves are a healthy, vibrant dark green. And the hornbeam’s foliage is no longer a drought-induced yellow after I established a regular and more intensive watering schedule, a reminder that recently planted trees require attention beyond their first year.
Plants are complicated organisms. You may prefer to do your own sleuthing to figure out their ailments, or you may decide you need assistance. Whichever approach you choose, a good place to start is with the research-based resources of your local university extension service. “Extension provides non-formal education and learning activities to people throughout the country — to farmers and other residents of rural communities as well as to people living in urban areas,” according to the National Institute of Food and Agriculture Extension website. Home gardeners are one of the audiences served by extension programs, with relevant resources available through services such as the University of Maryland Extension Home and Garden Information Center.
Turning to extension resources to research a problem or contacting extension experts for advice requires a bit of preparation. The more information you can provide about your plants, the easier it will be to evaluate the problem and find a solution.
- Identify the plant and include the cultivated variety, or cultivar. It’s important to keep a record of what you plant, preferably as you plant. But if you’ve lost track of this information, try to recover it with a plant identification app such as iNaturalist, PictureThis, or Pl@ntNet, or use the “Look Up – Plant” function available through an iPhone camera.
- Record the signs and symptoms that are causing concern. Signs indicate that pests or pathogens are present and include insect frass (droppings), insect egg masses and larvae, powdery mildew, and fungal mycelia (filaments). Symptoms are the plant’s expression that all is not well, such as stunted growth; wilting; yellowed, chewed, or dying leaves; and the development of cankers (areas of dead plant tissue) and galls (areas of swollen plant tissue). Study all parts of the plant (roots, stems, and the upper surfaces and undersides of leaves) and use a hand lens for magnified inspection.
- Assess the plant’s existing cultural, or growing, conditions and determine whether they are appropriate. Does the plant receive the right amount of sunlight and water, is the soil draining properly, does the soil pH match the plant’s needs, is the hardiness zone correct, and is the plant protected from wind if it’s susceptible to winter burn or other wind-induced conditions? All of these factors affect the health of the plant. Also note whether landscape conditions have changed recently (rerouting water flow in your yard, for example, may unintentionally inundate plants or leave them too dry) and if the problem may be mechanical (an injury caused by landscape equipment) or chemical (too much fertilizer applied or herbicides drifting from another area).
- Determine whether one species is affected or multiple species. If multiple species show the same symptoms, the problem may be cultural. If a single species is affected, the cause may be a plant-specific insect or pathogen.
- Document the problem with photos. Be sure to capture the problem with close-ups but also to zoom out and provide context. As you photograph, imagine which visuals an extension staff member will need to diagnose the problem. Take photos of the undersides of leaves and back sides of stems, if those areas are affected, and include pictures that show the plant’s location in the garden and its cultural conditions.
- Consult extension resources to research the problem or contact an extension service for assistance. This list of extension resources in the Mid-Atlantic region will help you get started.
Lawn and Garden, Cooperative Extension, University of Delaware
UD Plant Diagnostic Clinic, Cooperative Extension, University of Delaware
Ask Extension, University of Maryland Extension
Home and Garden Information Center, University of Maryland Extension
Home Gardening Resources, PennState Extension
Plant Disease Clinic, Department of Plant Pathology and Environmental Microbiology, PennState
Lawn & Garden, Virginia Cooperative Extension, Virginia Tech
Plant Disease Clinic, School of Plant and Environmental Sciences, Virginia Tech
And finally, keep observing. When you combine your observations as a home gardener with the knowledge of extension services, you improve the odds that your garden’s future is the one you want it to be.
If You’d Like to Learn More . . .
Beckerman, Janna and Tom Crewel. “Symptoms and Signs for Plant Problem Diagnosis – An Illustrated Glossary.” October 2021. Department of Botany and Plant Pathology, Purdue University. Accessed January 12, 2023. https://www.extension.purdue.edu/extmedia/BP/BP-164-W.pdf
Home & Garden Information Center. Clemson Cooperative Extension. Clemson University, South Carolina. Accessed January 13, 2023. https://hgic.clemson.edu/
IPM – Prevent, Identify, and Manage Plant Problems. University of Maryland Extension. Accessed January 12, 2023. https://extension.umd.edu/resource/ipm-prevent-identify-and-manage-plant-problems
National Plant Diagnostic Network. Accessed January 12, 2023. https://www.npdn.org/
Niemiera, Alex X. “Diagnosing Plant Problems.” Virginia Cooperative Extension Publication 426-714. School of Plant and Environmental Sciences, Virginia Tech. Accessed January 14, 2023. https://www.pubs.ext.vt.edu/426/426-714/426-714.html
Plant Disease and Insect Clinic. NC State Extension. Accessed January 13, 2023. https://pdic.ces.ncsu.edu/
USDA Plant Hardiness Zone Map. Accessed January 15, 2023. https://planthardiness.ars.usda.gov/
What is wrong with my plant? Arkansas Plant Health Clinic. Accessed January 13, 2023. https://www.uaex.uada.edu/yard-garden/plant-health-clinic/
What’s wrong with my plant? Garden, University of Minnesota Extension. Accessed January 13, 2023. https://apps.extension.umn.edu/garden/diagnose/plant/