JoAnne Skelly: Not all plant problems involve pests

Leaf scorch on an ash tree caused by water stress.

Leaf scorch on an ash tree caused by water stress.

One of the things University of Nevada Cooperative Extension is known for is diagnosing plant problems. When people bring in samples, we examine them to see what the problem is and what might be causing it. It often surprises people that most plant problems don’t involve a pest such as insects or diseases. With more than 85 percent of plant problems, the underlying cause is non-living or “abiotic” factors, which can include too much or too little water, soil issues, wind, nutrient deficiencies or improper pruning.

However, this is slightly misleading. It sounds as if I’m saying insects and diseases aren’t present on the plant. They actually might be, but often are a secondary factor in the plant’s overall declining health. Healthy plants resist insects and diseases. Stressed plants succumb and may actually invite insect and disease pests with hormonal stress signals.

It is important for a gardener to take good care of plants in the first place to avoid pests later. This includes watering thoroughly when you irrigate to encourage deeper roots that help a plant resist wind, sun and drought stress. It means letting plants dry out between watering so roots don’t rot. It means mulching around your plants to cool the soil, maintain moisture content and keep weeds at bay. Taking care of your plants includes fertilizing with the right amount of nutrients at the appropriate time of year. Proper pruning at the right time of year also will go a long way toward maintaining plant health.

If you are doing all these things, then keep your eyes open and watch your plants. Stress often shows up as a slight color change. A normally bright green plant may lose its luster, looking slightly gray-green. Or a plant may wilt, telling you that something is wrong with its roots — perhaps too little water; perhaps too much and roots are rotting. Observation will help you detect plant problems early, before a plant is at serious risk. Then, with correct identification of the issue, the pest or insect can provide a suitable solution to get your plant healthy again. Waiting too long might make saving the plant more difficult. This is the process of integrated pest management, a total-plant health approach to solving the “What’s wrong with my plant?” question.

From 2:30 to 4:30 p.m. Monday, Native Plants for Garden Pollinators will be the next free “Grow Your Own” class with the University of Nevada Cooperative Extension. Call 775-887-2252 for information.

JoAnne Skelly is the Carson City/Storey County Extension educator for the University of Nevada Cooperative Extension and may be reached at


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