Irrigation for Pest Control
I have been getting a lot of questions lately on summer plant health issues. Often, after a few descriptions of the problem I have an important question: How are you watering? In some cases the plant is wilting and it is clearly not getting enough water into the tissues, but in others the damage looks like it is insect or disease that is causing the problems. But if you go a bit deeper you may find that the obvious pest damage is actually only a symptom of a deeper problem.
How Much Water is Enough Water?First things first, before you can discuss problems that may be caused by improper watering, it helps to know what good watering looks like. Good soil will be evenly damp. Not soaking wet, but also not noticeably dry. If you stick a long screwdriver into it you will be able to push it down quite far and you will feel that the soil is slick and lubricated. If the soil is dry that screwdriver will feel like it is scraping and grinding. That is, if it gets into the soil at all. After only a few stabs into the ground you will be able to tell exactly where the water is in your soil. I should also note that most perennials and trees need the water deeper in the soil rather than in the top two inches. So as long as your plants are not newly sprouted or transplanted you should be all right if the top two inches go dry.
It is What's Happening Underground that Makes Things Hard!By under or overwatering a plant you cause many of the same symptoms. This surprises some people, but there is a very good reason for this. I think it is obvious to most that under watering will cause a dry and wilted looking plant with patches of crispy leaves. But when we talk about over watering it helps to think about the roots sitting in a puddle of water that never drains. As the plant sits there, the surplus water causes fungus to grow on the roots and damages them so that they cannot take up as much water. The longer the roots stand in the water the more they get damaged until the plant starts to wilt and dry up on top. Since the top is what we see the most often, many people only think the plant is dry because there is not enough water.
How Does this Help me With Pest Control?When a plant is stressed and weakened because it is missing a vital nutrient it becomes a target for any pest or disease wanting a free meal. Water is the most vital soil-based nutrient that a plant needs on a day-to-day basis. So if the watering for a plant is not right it can weaken a plant very quickly; and the opportunistic pests are already waiting for the opportunity to attack. It is that simple. Remember, most plants have a wide range of what they like for water, so as long as you are somewhere in that zone you will have a lot fewer pest problems.