Although summer doesn’t officially start until next week, it’s without a doubt summer-like weather. Temperatures are in the upper 80s, and rain is getting spotty. I strongly recommend irrigating young trees, shrubs, and perennials, as well as annual flowers and vegetables. Lawns that were seeded this spring should also be irrigated, to get them through the summer heat.
Proper irrigation is essential for healthy plants. My recommendation has always been to apply about 1 inch of water per week, all in one day. This allows the water to penetrate deeply into the soil, which encourages deeper rooting of your plants. Watering lightly every day merely wets the dust, encouraging shallow roots and unhealthy plants.
If you have an automatic sprinkler system on a timer, you need to do some experimenting to figure out how long to run the system. Yes, I’m sure the folks who sold you the system gave you some recommendations, but I’ve found that while they may be good at plumbing, they are generally not horticulturists, and do not understand plant needs.
To figure out how to apply 1 inch of water, get some cheap rain gauges, vegetable tins, or similar cans with straight sides. Spread them out throughout the area to be irrigated. Turn on the sprinkler system, and let it run for 15 minutes. When the sprinkler shuts off, measure how much water was applied. Let’s say, for example, that after 15 minutes, you discover that your rain gauges hold 1/4 inch of water. That means, to get 1 full inch, you will need to run your system for 1 hour (60 minutes). And that is ALL you need to do for that week (unless we are a couple of months into a drought and it’s been 95 degrees).
If you are watering a bed, one-half gallon of water per square foot provides the equivalent of 1 inch of irrigation. This is crucial to know if you are hand-watering, because nearly everyone I’ve ever seen who hand-waters is not applying anywhere near enough moisture. Use your hose and nozzle as you would if you were actually watering, and time how long it takes to fill up a one-gallon bucket. Let’s say, for example, that with your water pressure, hose, and spray nozzle, it takes 1 minute to fill the one-gallon bucket. That would mean you need to hold this hose over each square foot for 30 seconds to apply the needed half-gallon of water. If you have a modest sized garden bed that is ten feet long and 3 feet wide, that means you need to stand there for at least 15 minutes to adequately water this garden bed! Hand-watering is very inefficient and time-consuming!
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More Heat-Related Concerns
I have seen numerous trees and shrubs around the tri-state that leafed out this spring, and then suddenly wilted and died. Often, only a branch or two of the plant does this. So far, the vast majority of plants I’ve examined showing this symptom did not have an infectious disease causing this, although there were a couple of pears and crabapples that had fire blight.
From what I’ve seen, there are several possible causes. One scenario is cold-injury, especially from the sudden drop in temperature to the low 30s we saw back in March, and again in April. Most plants lost tiny, delicate leaves that had just budded out, but have since put on new leaves that are normal. However, some cold-sensitive plants, like crape myrtle, lost large pieces of the plant due to cold. They have mostly resprouted from the base by now.
Many of the plants I’ve seen with the dieback have had other problems. Several plants had injury to their trunks, especially “mower blight” and “weed whacker disease”. Others have had obvious signs of trunk-girdling roots, which are strangling the plants. These conditions restrict the amount of water that can come up from the roots to the rest of the plant. There was just enough moisture making it upwards for the buds to open and the leaves to begin growing. However, as soon as we started hitting the 80 degree weather in May, the leaves were losing water faster than they could be resupplied, and so they wilted and died.
I’ve had some people question me on this. “Look, I can still bend the twig, so it must be alive still, right?” Well, not necessarily. It takes time for a twig to dry out and become brittle. A better way to check is to scratch the bark on a twig with your fingernail. If the underlying tissue is green, it’s a live. However, if the underlying tissue is yellow or brown, it is dying/dead.
Branches that are dead or leafless by mid-June are not going to recover. They should be pruned off now, for cosmetic purposes. If you want to wait, it won’t hurt anything, but that depends on how the plant looks to your eye. Right now, with the summer rolling in, removing dead branches is the only major pruning I will be doing from now until winter.
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Pests Being Seen
Azalea Lace Bug is on practically every azalea I’ve seen in the past month. You won’t likely see the actual pest, which lives on the undersides of the leaves. However, the damage it causes is unmistakable. Look for tiny white speckles on the leaves…this is caused by both the larva and adult sucking out the contents of individual leaf cells. You will also notice tiny, shiny black dots on the undersides of the leaves – this is the insect’s fecal matter (poop). Easiest way to control them is with a soil application of imidacloprid (such as Bayer Tree and Shrub Insect Control). Since the blooms have faded weeks ago, there is no danger to bees. Check the label before buying, because the size of the plants determines how much product you need. Read and follow all label directions!
Bagworms are hatching out now. While they can be on almost any plant, they prefer small-needled evergreens, such as junipers. Spray them now with Bt (a natural bacterial product that only kills caterpillars; sold as Dipel and a few other trade names). Bt works great on newly hatched bagworms; if you wait until July when they are bigger, it won’t work as well, and you’ll need to use more conventional insecticides.
Japanese beetles should be emerging from he soil now. Although I’ll be honest, I haven’t seen any yet, personally. Soil applied systemic insecticides, such as imidacloprid, are the best control, as they poison the beetles for up to 3 months. Foliar-applied sprays need to be reapplied every 7 to 10 days. The problem with insecticides is that the beetle must feed on the plant in order to be poisoned, so you will still see beetles on your plants, and you’ll see holes eaten into your leaves. Do not reapply insecticides more often than the label recommends, because you are wasting money, harming the environment, and not going to kill the beetles any deader than they already are.
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What Can Caplan’s Do For You Now?
Diagnostics: Lots of insect and disease organisms are taking off now. You need to know what is causing your plant’s problems before you can start treating for them. Especially since many problems are caused by physical or cultural reasons, and spraying won’t do you any good at all. Before you spend money on spraying, injecting, or feeding your plants, be sure that it will do you some good!
Tree Risk Assessments: Storms can cause even healthy-looking trees to fail. Protect your family, your home, and your liability by having trees inspected before they fail. It may not be necessary to cut down every tree on your property…but you also don’t want to leave a potentially dangerous tree standing. I am the only Tree Risk Assessment Qualified arborist in southwestern Indiana.
Plant Selection: I have always promoted “planting the right tree in the right place.” All too often, homeowners (and professional landscapers) plant trees and shrubs that won’t survive to their full lifespan. Maybe the plant is too big for the area it was planted in. Maybe the soil is not adequate for the plant you want. If you are planning on landscaping your property, I can examine your site and make recommendations. Or, if you’ve been given a landscape design by a professional, I can review it to make sure that there will be no long-term problems. My fee is small, compared to the cost of planting, and then replanting, your landscape.