Planting season is just around the corner!  You may have noticed that some varieties will have some letters following the name on the plant labels.  These are showing resistance to common plant problems.  One of our best defenses to these common pest problems in the garden and landscape is plants with natural resistance. By selecting varieties of plant species, or species that are inherently resistant to common pest problems, the use of pesticides needed to keep our plants looking good can be reduced.

When buying seeds or plants, try to choose those with built-in resistance to diseases, insects, and nematodes. Sources for this information include OSU Extension Fact Sheets, seed catalogs, and plant and seed packages. Sometimes it is a choice between an old favorite or a new resistant variety.  If you have not had issues and are willing to monitor and watch, you may want the old favorite for a certain flavor or color.  The resistant varieties do make gardening much easier if you want to avoid certain issues.

During the growing season, stressed plants can lose their resistance to pests, so be sure the crop has the water and nutrients it needs. When shopping for seeds and plants, check the labels for indications of pest resistance. For example, many garden phlox and crapemyrtles are susceptible to powdery mildew fungal disease; however, several varieties are available that are resistant to powdery mildew. When purchasing vegetables, check labels or packaging for abbreviations similar to these, used to designate various types of pest resistance or tolerance:

A-Alternaria stem canker


ALS-angular leaf spot

NCLB-northern corn leaf blight


PM-powdery mildew

CMV-cucumber mosaic virus

SCLB-southern corn leaf blight

DM-downey mildew

St-Stemphylium (gray leaf spot)

F-Fusarium (race 1)

SW-Stewart's wilt

FF-Fusarium (races 1 & 2)

TMV-tobacco mosaic virus



MDM-maize dwarf mosaic

Please do note, these natural resistance traits are genetic, not chemically added.  Watch for labels on ornamentals that may have been pre-treated with chemicals.  Some of these chemicals (the Neonicotinoids) are very harmful to bees and pollinators and should be avoided.