During the gardening season I always get calls or emails asking what's wrong with a plant and what can be sprayed to help make it better. If you're like me, we love our plants and we want to make sure that they continue to grow healthy and happy in our landscape. It's always sad seeing a plant that is slowly fading away for one reason or another and we sit and try to figure out what is going wrong.
Whenever I receive that call or email I always ask for more details. How old is the plant, where is it located, I'll think to what the weather has been like, what might the plant be susceptible to (disease or insects), what are the optimum growing conditions for that plant, soil requirements, light requirements, the works. I make sure to ask what kind of care the plant is given and if the person can provide me photos of the entire plant to get a better idea of the situation. Diagnosing plant problems requires some level of detective work, but for me that's part of the enjoyment of it, putting all the pieces together to figure out what is going on.
In our Master Gardener training program one of the sections we cover is Integrated Pest Management (IPM), which looks at different facets for plant care and pest management. IPM includes cultural, physical, biological and chemical controls – with chemical controls being the last resort. Cultural includes right plant right place, proper pruning and maintenance, sanitation, mulching, and watering – the basic tenants of proper plant care.
Physical includes things such a hand picking insects, physical barriers to keep insects out, and weeding to name a few. After that comes biological which is encouraging predators and parasitoids, natural enemies of unwanted insect pests. Finally, if all else fails we can look to chemical controls for insect, disease, or weed control. Of course before we can use chemicals, it's imperative to diagnosis what the problem is. Can it be corrected through the other three pillars of IPM? Is the problem something that needs treated? Maybe the problem is simply aesthetic and doesn't impact the overall health of the plant and no treatment is necessary or maybe it's a situation where chemical controls will ensure the survival of the plant.
The most important factor is making sure to identify the problem and not resort to spraying something before we know exactly what we are dealing with. Sometimes the answers might be multi-faceted. For example, trees that are under stress from improper planting or the wrong soil conditions can become more susceptible to insect and disease issues – so if we can pro-actively provide the right cultural care we can help to minimize the occurrence of issues. I use the example that if we don't get enough sleep, don't eat right, and don't drink enough water - we can get worn down and it can lead to us getting sick, trees and plants can be the same way. If plants don't have what they need to stay healthy they can become susceptible to diseases and insects.
It should be noted that sometimes no matter how careful or proactive we are there are times that chemical controls have to be implemented – Emerald Ash Borer (EAB) is a great example. Trees that are not treated have a 100% mortality rate – chemical treatment is absolutely necessary to prevent infestation. (Note – research does not recommend treating for EAB until it has been found within 15 miles)
So what's the morale of the story? Right plant right place, proper care, etc. and then if problems arise become a plant detective before spraying and/or contact your local Extension office for assistance in diagnosing what the problem is.