Here’s a good process to troubleshoot plant problems

What's wrong with my plant? Step back 10 big steps and take a hard look at it. Ask yourself a few questions and compare it to others in your neighborhood.

I ask lots of questions when I troubleshoot a yard. Did you fertilize or apply chemicals recently? If so, what did you use and how much? I then slowly put the puzzle together.

Sometimes there are no quick answers to troubles. It might be a combination of many things. Plants can't talk, so I go on visual symptoms. Sometimes I run tests to make more educated guesses.

Many concerns may never be issues. For example, evergreen trees and shrubs are shedding last year's leaves so that is OK. If falling leaves still concern you, are the branch tips green and pliable? In most instances they are.

Let me take you through a thoughtful process to diagnose plant problems.

Compare your questionable plant to normal plants. If your neighbors have healthy plants, find out what they are doing right.

Look at leaves because they are the most visible. Small, pale green leaves indicate a need for nitrogen. Tiny leaves clustered at branch tips suggest a zinc concern, especially in fruit trees. Small cupping leaves indicate a need for more water.

If leaves wilt, expect waterlogged soil. Dig up a handful of soil to smell; a sour smell confirms poor drainage. Poor drainage also brings on root rot. If the root skin sloughs off and is water-soaked, it's root rot. Cut back the water and improve drainage. Check other roots, because it might be bad on one side but good on the other.

If the roots are OK, check the plant crown where roots branch off the trunk. Slit the bark to examine tissues underneath. Brown vascular tissue suggests a disease called crown rot. If the tree is salvageable, pull soil away from the crown and fill with pea-gravel to keep the crown dry.

If you used a pesticide or fertilizer, suspect an overdose, especially if applied recently. Chemical misuse is a common mistake. A gardener lost a beautiful arborvitae for no apparent reason. Hidden behind the bush was a broken water softener salting the ground.

Yellowing leaves with pronounced green veins, especially younger leaves, suggest iron deficiency. As it worsens, expect twig dieback, particularly in fruit trees and eucalyptus.

In pears and eucalyptus, iron problems start by expressing freckled spots (pears black and eucalyptus red) on leaves. Pear leaf edges later blacken along edges, while eucalyptus leaves become small. Twig dieback follows. Use iron chelates such as Kerex. It doesn't lock up with our alkaline soils. Apply it to the soil for longer-lasting results. For temporary relief, spray iron directly on leaves. Use a spurt or two of detergent in the water solution to spread iron uniformly across leaves.

Leaves with brown around the edges send out signals suggesting a need to flush away the soil salts. Browning along leaf edges also results when excessive winds sap trees of moisture. Irrigate deeply every two weeks to prevent further browning. Expect more leaf scorch in sycamores.

This time of year, you'll see bronze-colored pyracantha leaves. They suggest spider mites feasting on the leaves. Thoroughly wash off plants and spray with insecticidal soap. These tiny but mighty pests also sap moisture from Italian cypress, leaving them in a droughty condition.

If you suspect bugs but can't find them, they may be nocturnal insects. Search for them in the evening, and if you find them, spray under the plants for best control.

If you're still having problems, solicit the services of a horticulture consultant. Here are some questions you may be asked:

■ What kind of plant is it? If it's a popular tree, several possibilities come to mind: leaf scorch, iron chlorosis, crown gall, cytospra, leaf miners and exposed roots. No, simply saying a plant with green leaves, a stem and branches does not help. Many callers don't offer much more information than that.

■ What are your watering habits (how often, how long, how deep and how is it applied)?

■ What kind of fertilizer or chemical has been used, how much and when? For example, twisted tomato leaves suggest a misuse of 2,4-D near vines.

Provide a fresh sample showing the problem. Or send pictures by email. Provide clear examples of the overall situation. The more pictures to evaluate, the more accurate the diagnosis will be.

Linn Mills writes a gardening column each Sunday. You can reach him at linn.mills@ springspreserve.org or (702) 822-7754.