Environment is usually the key to solving plant problems

July 07, 2009|By ANNETTE IPSAN

It's easy to blame insects and diseases for plant problems. It must be bugs or some foul disease making your plants look unhealthy, right? The truth is that more than half of all problems with plants are caused by their environment.

Too much or too little rain, heat and cold, wind, compacted soil and many other environmental factors cause a host of problems for plants. Some are minor, some major, in their impact.

Let's look at a few recent samples from client visits and calls.

"My tomato leaves are curling," said a distraught client this week, adding her voice to a dozen others with the same complaint. Leaf curl has several causes, but the samples I've seen have all been deep, healthy green without a single insect or disease symptom. What's the cause? Rain, rain and more rain this spring has caused tomato leaves to curl. It doesn't harm the plant or effect harvest. The plant will grow plenty of normal, uncurled leaves once it gets hot and dry and stays that way.


"My Leyland cypress has brown tips," said another visitor who showed me photos and samples of the damage. Several things can cause browning in Leylands, but this was classic winter burn caused by the extreme, persistent, frequent winds this winter. Horticulturalists across the state are reporting random browning in Leyland cypress without any insect or disease symptoms. In some cases, it is causing sporadic brown patches. In other cases, entire trees die. Leyland cypresses hate wind.

Star magnolias are notorious wimps when it comes to the cold. This spring was fairly mild, so I didn't get the normal flurry of calls about sudden browning of blooms. Star magnolias bloom early and often get zapped by a late frost. It doesn't harm the tree, but causes you to miss the lovely show of starry white blossoms.

One client recently e-mailed me a photo of a tree with a shallow, horizontal gash about 8 inches from the ground. I asked him who mows the lawn and he told me his teenage son does. I informed him his tree had a bad case of "teen mower syndrome," and was the unfortunate victim of an adolescent eager to finish his chores. Weed whackers can cause the same problem.

Sometimes environmental conditions trigger insect or disease problems. Shade-loving azaleas planted in the sun get stressed and are fed upon by lacebugs, which cause lots of yellow dots on the leaves with their feeding. Tomatoes watered unevenly get blossom end rot, blackened spots that are evidence of a calcium deficiency. Both problems are treatable.

What lessons can we learn from a brief look at some environmental problems? It's important to put plants where they can thrive, be that in the sun or shade, dry or damp soil, in or out of the wind. Giving plants extra protection from the elements is helpful, too, with practices like mulching or regular, deep watering. Most important is looking at your plants regularly to spot potential problems early so you can figure out a cause (with my help, if needed) and an action plan.

Annette Ipsan is the Extension educator for horticulture and the Master Gardener program in Washington County for the University of Maryland Cooperative Extension. She can be reached weekdays by telephone at 301-791-1604, or by e-mail at

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