Learn what to look for while you shop!
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| Coleus for sale at a local garden center Photo: M. Grabowski, UMN Extension |
Many plant pathogens are able to hitch a ride from one garden to the next by infecting plants before they are sold or shared. This can result in disease problems for years to come as the new pathogen becomes established along with the new plant.
In the worst case scenario invasive pathogens are brought in from outside of Minnesota and escape the garden to cause disease in Minnesota native plants. White pine blister rust, a devastating invasive disease of white pines, was first brought into the USA on infected pine seedlings.
Whether you are looking for tomato transplants, annuals or
perennial flowering plants, or a new tree or shrub, take the time to follow the
simple recommendations below to purchase healthy plants.
Inspect every plant
prior to purchase
Dark wilted stems indicate this periwinkle is infected with a plant pathogen.
Photo: M. Grabowski, UMN Extension
Photo: M. Grabowski, UMN Extension
At the nursery or garden center, carefully inspect every
plant prior to purchase.
- Look at the upper and lower leaf surfaces for spots, discoloration, unusual growth or other signs of disease.
- Examine the stem. Are there any open wounds, excessive sap, discolored or soft mushy areas? These could all indicate a disease problem.
- Examine the roots. They should be firm and light colored with many fibrous root hairs. Dark mushy areas may be infected with a root rotting pathogen.
Implement a strict
‘no pests allowed’ policy
- Choose only healthy looking, vigorously growing plants for your garden.
- Reject any plants showing symptoms of disease.
- Never try to save a sad looking, weak plant. The proper place for these plants is in a compost pile that heats up enough to kill any pathogens.
Reject plants with
sick neighbors
Snap dragon transplants with root rot.
Photo: M. Grabowski, UMN Extension
Photo: M. Grabowski, UMN Extension
Nursery plants are often grown close together, grouped by
plant type or variety. The plants within a group are all pruned, watered and
fertilized at the same time. If one plant in a group is diseased, it is easy
for the plant pathogen to move from one plant to another during these maintenance
practices. If several plants in a group appear
diseased, do not purchase any of the plants within the group.
Choose plants suited
to your site
Read plant labels to look for disease-resistant varieties and
to find out if the plant will thrive in the conditions in your garden.
Photo: M. Grabowski, UMN Extension
to find out if the plant will thrive in the conditions in your garden.
Photo: M. Grabowski, UMN Extension
Read the plant tag carefully. Is this plant hardy in your
area? Will the plant thrive in the conditions of your garden? Plants stressed
by cold, drought, too much sun or shade or other environmental problems often suffer
from disease problems in addition to environmental stress.
Look for disease resistant varieties
Whenever possible purchase plants that are bred to be disease
resistant. Many common disease problems like apple scab on crab apple, powdery
mildew on phlox and Verticillium wilt on tomato can be avoided altogether by
growing disease resistant varieties. Disease resistance is often listed on the
plant label.
Certified disease
free plants
Rose Mosaic Virus
Photo: M. Grabowski, UMN Extension
Photo: M. Grabowski, UMN Extension
Some plants like roses and hostas are screened by some
nurseries to verify that they are free of viruses like Rose Mosaic Virus and
Hosta Virus X. Ask at the nursery if these plants have been screened or
‘indexed’ for virus prior to purchase.
What about dividing
and sharing plants?
Splitting and sharing perennial plants is a tradition as old
as gardening itself and can be a cost effective way to grow your garden while connecting
to friends in the gardening community. If you are receiving plants from a split
perennial, accept plants from someone you know and trust. Volunteer to help dig
and split plants. This will allow you to see the mother plant.
Select vigorously growing plants for division. Examine the plant carefully for any signs or symptoms of disease. Look for spots, discoloration, unusual growth, or rot on all plant parts. Reject plants that have symptoms of a disease. Healthy looking, vigorously growing plants can be split and shared.
Gardeners may choose to take extra precautions by isolating the new plant in an area away from the main garden bed for a year to watch for potential problems. This way, if a disease problem does come up, the plant is easily removed and it is less likely to spread to your other well established perennials.
Select vigorously growing plants for division. Examine the plant carefully for any signs or symptoms of disease. Look for spots, discoloration, unusual growth, or rot on all plant parts. Reject plants that have symptoms of a disease. Healthy looking, vigorously growing plants can be split and shared.
Gardeners may choose to take extra precautions by isolating the new plant in an area away from the main garden bed for a year to watch for potential problems. This way, if a disease problem does come up, the plant is easily removed and it is less likely to spread to your other well established perennials.
