JoAnne Skelly: Diagnosing plant problems

Sometimes the cure for a dry spot in the lawn is as simple as the application of a little water.

Sometimes the cure for a dry spot in the lawn is as simple as the application of a little water.

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Figuring out the answer to “What’s wrong with my plant?” takes a plant detective.
First, identify the plant.
Then, collect data about irrigation practices, maintenance, soil type, fertilization, exposure to light or wind, and the age of the plant. Ask yourself lots of questions. “When did I first notice the problem?” “Is the plant happy with the regularity and quantity of water?” If a drip system is used, “How many emitters are there per plant, what gallon amount per hour and how long do I run the drip each time?” “Have I verified that the emitters are still working?” “Have I increased the number of emitters per plant as it grew?” To find out about potential soil problems, examine the drainage. Plants don’t like soggy feet.
Since biological plant problems are usually limited to one specific kind of plant, see if other kinds of plants are suffering similarly, or just this one plant or groups of this plant. If trees and/or other plants are suffering that are in or near a lawn, “Did I use weed killer/fertilizer combination products?” The weed killer can hurt and even kill trees, shrubs and flowers.
Or, “Did I apply insecticides in a sprayer that had previously been used for herbicides?” That could injure a wide variety of plants. Maybe an outside cause is involved. “Is there bird or animal damage to the trunk or stems?” “Have I damaged a trunk with a lawnmower or weedeater?” “Has there been construction in the area or a gas leak?”
With lawns, “Do I know how many inches of water per week I am applying” If not, do the ‘can’ test to measure the amount applied, the evenness of coverage and to see if the sprinklers are working efficiently.
“Am I watering often and deeply enough at a cool, non-windy time of day?” Be sure to increase the amount of water applied as the temperatures heat up. “Could I be mowing too short?” Mowing longer is better during the heat. “When, how often and with what do I fertilize?” If there are dead or brown spots in a lawn, “Is my female dog using the area?” Her urine kills the grass.
Most plant problems are cultural rather than biological in origin. We have almost no plant disease issues here. Problems are usually caused by inefficient watering, improper pruning, poor maintenance or improper pesticide application. Being aware that it’s usually us causing the problem rather than nature can help resolve a plant issue more easily.
JoAnne Skelly is Associate Professor & Extension Educator Emerita at University of Nevada Cooperative Extension. Reach her at skellyj@unr.edu