Margaret Lauterbach

Too much moisture can wreak havoc with plants

Into the garden with Margaret Lauterbach

Idaho Statesman gardening columnist Margaret Lauterbach spends time in her early spring garden, reflecting on why we love gardening so much.
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Idaho Statesman gardening columnist Margaret Lauterbach spends time in her early spring garden, reflecting on why we love gardening so much.

We’ve had a wetter than usual spring that may ultimately be harmful to many different parts of our landscape. Splashing water distributes fungi (funguses if you prefer) that may result in blight on tomatoes, peppers and other Solanaceous plants, black spot on roses, or even needle drop on spruce trees. If the weather turns suddenly hot and dry, and the heat lasts, it may put a stop to the spread of those diseases and reduce the hatch of some insects such as grasshoppers whose eggs could be destroyed by dry weather. That would not stop the rapid snowmelt in the mountains, however.

Your best defense against those diseases is mulch that prevents water splashing from soil to leaves. Shredded leaves from last fall’s cleanup or your own grass clippings that are free of pesticides work fine. Or use bark chips or soil aid. If you’re new to this area, soil aid is composted sawdust, less available as lumber mills shut down.

If you have spruce trees in your yard, especially Colorado blue spruce or Englemann spruce, start checking the needles for signs of disease. Debbie Cook, certified arborist with Boise city Parks and Recreation’s Community Forestry division, said the prevalent spruce disease is Rhizosphaera needle cast, and that the disease doesn’t show up on the new sections of needles, but that of last year’s needles, just behind the new (outer) needles. Further toward the trunk may be bare, due to old needles having dropped, a natural occurrence.

This fungal disease is spread by splashing water onto lower branches from last year’s needle drop, telling you that one way of preventing it is to remove old needles from under the tree or installing a non-splashable mulch. Healthy needles should be uniformly dark green or blue-green. If there is discoloration of any kind such as yellow, purple or brown, use a hand lens of at least 10X magnification to examine the needles. If there are black dots on the needles, the tree may need treatment. If you’re unsure, contact an arborist. The disease may be controlled by use of appropriate fungicide, applied when needles are 1/2 to 1 1/2 inches long. A second application should be applied three to four weeks later. Many trees recover completely, especially after two years of treatment.

The disease can kill young spruce trees, but probably not mature trees. Untreated, branches will lose needles a few years in a row, and then you’ll wish it died since it’s dropped its beauty.

Keep your tree healthy by keeping the root area free of weeds and lawn grasses that could stress the tree, and add a thick layer of wood chips around that area to retain soil moisture and deter weeds, and retrain lawn sprinklers so that they do not wet the tree’s needles.

A moist spring may also mean emergence of peach leaf curl on peach, nectarine, apricot, cherry and almond trees. There’s nothing to do about that extensive puckering now, but make note of it so you can treat it in fall and January. Also, watch out for evidence of coryneum blight, or shothole fungus on trees bearing stone fruit. Symptoms include small round spots on leaves, usually red-purple or tan, that eventually die and fall out of the leaves leaving the shothole effect. This is a common, but tough, disease. You can fight it with judicious pruning and fall applications of appropriate fungicides.

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Always remember, gardening is your own project. You can make it fun in different ways, such as sowing seeds, for instance, in the shape of a face or a dog. Or you can plant a honeymoon plot, lettuce in a container, lettuce alone. Now a new serio-comic project has been found: jockey shorts soil test. Amusing idea, but it works.

As many of you know, folklore says the soil is warm enough to plant if a bare-bottomed gardener can sit comfortably for 5 or ten minutes on garden soil. Now esteemed institutions such as the University of Guelph (Canada) and Clemson university (South Carolina) have conducted soil tests using men’s cotton jockey shorts, known as “tighty whities.” To determine the level of microbial activity in your soil, bury a pair of clean 100 percent cotton jockey shorts (not treated with bleach, so new is probably best), leaving the waistband exposed so you can find them again.

Leave them in the soil for at least three weeks, preferably two months, then pull out the shorts to see how much has been consumed by carbon-seeking microbes. If they’re intact, your soil is not healthy. You need to work in a lot more organic matter to nourish existing microbes and to encourage a larger population of them. The better health of your soil, the better your garden grows. The more deterioration of shorts fabric you see, the healthier your soil.

Send garden questions to or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.