When we notice a plant problem, the instinct is to grab a pesticide spray.
That’s not the answer; it’s critical to find out first what the problem actually is.
Diagnosing what’s wrong can be overwhelming; however, there’s help for you. For a plant disease, killing it is difficult or impossible.
Understanding how plant diseases develop and how to prevent them is the better approach to control.
The disease triangle. For any plant to be infected with a disease, three things are necessary: a susceptible plant, the contagious disease pathogen, and the right environment. Plant disease can be minimized, prevented, or managed by disrupting one factor of the triangle.
The environment can be the most difficult to control since weather plays a part: from abnormal rain to extended periods of high humidity. Our spring weather was abnormally wet; therefore, we should be on the lookout for disease issues this summer. Leaf spots, fruit blemishes, wilt, stunted or disfigured growth; an unusual color can all be symptoms of a disease issue.
Disease prevention. Plant more disease-resistant varieties or use different, less problematic plants such as natives which exhibit more natural disease resistance. Provide the right growing environment and add plenty of organic matter to soil such as compost.
Reduce the spread of disease pathogens by keeping areas clean of plant debris. Keep tools and garden gloves clean to not spread disease bacteria to other plants. Avoid crowding plants to improve air flow. Add mulch around the base of plants to prevent soil splashing, a common way for soil-borne diseases to infect the lower leaves of a plant.
If using a fungicide, understand that they are limited to no curative properties. They are only preventative; use them before or when symptoms first occur. Once the disease has progressed, fungicide will not help. Always read product labels and use them only as directed. While most fungicides are not toxic to pollinators, minimize exposure by spraying in the evening when pollinators are not active.
Know your plant’s normal appearance so it will be easier to notice when something is wrong. It’s critical to correctly diagnose the problem.
There are several phone apps to help you such as Plantix, Agrio, PictureThis, PlantSnap, and Plant Disease Diagnosis; fees may apply. Don’t just depend on an app; there’s also the Cornell Plant Disease Diagnostic Clinic website at https://plantclinic.cornell.edu/factsheets/.
Cornell Cooperative Extension Oneida County answers home and garden questions which can be emailed to homeandgarden@cornell.edu or call 315-736-3394, press 1 and ext. 333. Leave your question, name, and phone number. Questions are answered on weekdays, from 8am to 4pm. Also, visit our website at http://cceoneida.com/ or phone 315-736-3394, press 1 and then ext. 100.
This article originally appeared on Observer-Dispatch: Understanding plant disease
Reporting by Utica Observer Dispatch / Observer-Dispatch
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