An Unwanted Visitor

Yellow leaves in the home landscape during spring are likely a sign of problems. However, it will take some detective work to determine the exact problem and how to correct it.

Look on the leaf’s surface and underside to see if any insects are present. If so, you could be dealing with aphids.

These small, pear-shaped insects use piercing mouthparts to savage plants’ vascular systems and drain them of their life-sustaining fluids. Aphids also transmit viruses, so keep an eye out for them, especially in the spring when female nymphs start to hatch. 

Another potential culprit behind your yellow leaves is scale insects — a diverse group of “piercing-sucking pests.” They’re small and inconspicuous and use hair-like mouthparts to remove and consume plant sap from leaves or branches.

There are several families of scale insects, but you can divide them into two main groups: soft and armored.

Armored-scale insects feed on the contents of cells just under the surface of leaves and bark. Once a female armored scale feeds on a host plant, it will stay immobile on that plant for the rest of its life.

Conversely, female soft scales are mobile during every life stage until they begin to produce eggs. Soft scales feed on plants’ phloem vascular tissue, which transports the soluble organic compounds made during photosynthesis and causes plant damage.

To eliminate these pests, experts recommend treating affected plants with organic horticultural oil sprays. You can also plant flowers to attract other insects — such as ladybugs and lacewings — that feed on aphids and scale.

Leyland Cypress in the landscape

Photo by iStock / Getty Images Plus: dbvirago

Want to add something new to the home landscape? Leyland Cypress trees can produce dense green foliage in a relatively short time.

When left alone, Leyland Cypresses will grow 50 feet tall and form oval or pyramidal outlines; however, they can handle severe pruning, meaning you can shape the trees to create formal hedges. Still, they must receive ample room to mature.

This salt-tolerant species will flourish in various soil types, including the clay soils often found in and around Tallahassee. Just be sure to plant your tree (or trees) in moderately fertile soil with adequate moisture. It’s also worth noting that they’ll need exposure to full sunlight for superior growth, but they’ll tolerate partial shade if necessary.

Also, beware of bagworms — total defoliation can occur within two weeks of infestation. So, check your cypresses regularly and take all proper precautions to keep them healthy.

Earthworms

Earthworms improve gardens by aerating the soil and feeding beneficial wildlife. Photo by iStock / Getty Images Plus: PhotographyFirm

There are several indicators that soil is healthy and productive, but one in particular is not visible from the surface — earthworms. These wet and wiggly creatures live in the top few inches of the soil, and while they may not be pretty to look at, they’re very beneficial.

For one, they eat a variety of organic materials, both dead and alive. For example, pine straws and mulched flowerbeds from last year’s leaves serve as larders and living spaces. Earthworms also consume and convert cellulose remains into the nutrients plants need, and they eat nematodes, fungi and other potential problem microorganisms.

By aerating soil, earthworms make root growth easier and help improve water retention. And, they are a food stock for other ecologically necessary creatures, such as birds, frogs and beetles.

Photo by iStock / Getty Images Plus: davidforeman

Les Harrison is a retired University of Florida/Institute of Food and Agricultural Sciences Wakulla County extension director.