Managing Difficult Plant Diseases: Disease control is preventative, not reactive

Apple scab disease on crabapple occurs only on certain crabapple types. Though it does not kill the plant, it may make them unsightly with considerable leaf drop. Photo courtesy James Chatfield


By James Chatfield, Joseph Boggs, and Erik Draper

Since green industry professionals cannot see inoculation and infections occur, they must act proactively with regard to plant diseases. In many cases, this means they need to use fungicide applications to prevent the germinated fungal spore from getting into plant tissue in the first place (though there are systemic fungicides that sometimes help).

A better, more sustainable approach is to employ their knowledge of genetic disease resistance, plant health, and plant stress management to optimal effect. Green industry professionals need to recognize Sargent and Adirondack crabapple have excellent resistance to apple scab, compared to thunderchild and hopa. If they know there is a site with the Verticillium fungus well-established in the soil, which they can know from previous Verticillium wilt diagnoses, then they should not plant highly-susceptible species such as Japanese maples (Acer palmatum).

Selecting the right plant for the right site is the greatest preventive maintenance practice tree professionals can use, not only for infectious disease management, but also for overall plant health. Eastern redbuds planted in open sun on unirrigated sites are more likely to become moisture-stressed and are more likely to have Verticillium wilt problems as well as Botryosphaeria canker disease—the two most common infectious disease problems of Eastern redbuds that cause stem dieback and eventual plant death. Preventing these diseases from the very beginning can occur by not planting redbuds in those sites.

Read the full article: Managing Difficult Plant Diseases

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