One of the things I used to do at University of Nevada Cooperative Extension was diagnosing plant problems. When people brought in samples, other Extension staff, volunteers and I would examine them to see what the problem was and what might be causing it. It often surprised people that most plant problems didn’t have a pest involved such as insects or diseases. With more than 85 percent of plant problems, the underlying cause is a non-living or “abiotic” factor, such as 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 as a secondary factor due to the plant’s overall declining health. Healthy plants resist insects and diseases. Stressed plants succumb and might 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 a bit between watering, so that 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 will also go a long way toward maintaining plant health.
If you are doing all these things, then keep your eyes open and observe your plants regularly. Stress often shows up as a slight color change. A normally bright green plant might lose its luster, looking slightly gray-green, or a plant might wilt, telling you that something is wrong with its roots — perhaps too little water; perhaps too much and roots are rotting. Diligent observation will help you detect plant problems early, before a plant is at serious risk. Then, correct identification of the issue, the pest or insect may provide a suitable solution to getting your plant healthy again. Waiting too long might make saving the plant more difficult, and, in some cases, impossible. This is the process of integrated pest management, a total plant health approach to solving the “what’s wrong with my plant” question.