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Roses are susceptible to a number of disease and insect pests. Roses may survive without a basic pest control program, but they may not be very attractive. A pest control program starts with proper site selection, good soil preparation, good drainage, proper spacing, cultivar selection, and plant maintenance. These all foster healthy roses that are better able to withstand the pressure of disease and insects.
When selecting roses, note the resistance to disease of a particular cultivar or named variety within a class. You want to select by cultivar, not by class. All too often, many gardeners assume that shrub roses (the class) are very tolerant or resistant to disease and make their selection based solely on class. In fact, there are a number of cultivars that are very prone to severe disease injury.
Another interesting fact about diseases is that plants can have two types of resistance: phenotypic or genotypic. Phenotypic resistance is when a cultivar is resistant to a disease in one location or part of the country but not in another. Genotypic resistance is due to the presence of genes that are not affected by climate, location, or horticultural practice. That is why, when the term "resistance" is used as a blanket term and assigned to a variety or class, it may or may not apply depending on where you garden.
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