Pesticide injury in the landscape
Editor’s note: This article is from the archives of the MSU Crop Advisory Team Alerts. Check the label of any pesticide referenced to ensure your use is included.
MSU Diagnostic Services worked on several pesticide injury complaints in the landscape in 2005. Pesticides can injure desirable landscape plants by drift, volatilization, carryover, tank contamination, misapplication or simply the accidental or intentional spill or exposure to a pesticide.
All plant samples submitted to our multi-disciplinary plant health and pest diagnostic facility are visually inspected for pesticide injury. If warranted, samples can be tested for the presence of pesticides using appropriate analytical instruments and techniques. This article will briefly explain some of the injury symptoms we observed and our diagnosis of the problem.
Picloram (Tordon) injury on yew (view images)
Distorted, malformed new growth was observed on yew branches soon after an herbicide application in a nearby planting bed. Tordon was applied to honeysuckle stumps and sprouts in this bed. Unfortunately, Tordon has the ability to leach through the soil profile to injure neighboring plants.
Flumioxazin (Valor) plus glyphosate injury on maple (view images)
Foliage from several landscape plants contained similar necrotic spots and wilting. The pattern of injury on the property suggested herbicide drift from a neighboring soybean field treated with a burndown of Valor plus glyphosate. Flumioxazin was detected at 0.18 ppm on the foliage.
2,4-D injury on oak (view images)
The newer growth of an oak tree contained twisted, cupped and bubbled leaves. This injury was noticed soon after an herbicide application in a nearby lawn. The pattern of injury suggested herbicide drift or volatilization of a broadleaf herbicide used in the lawn. 2,4-D was detected in the tissue.
Natural gas leak in a lawn (view images)
A homeowner had a circular-shaped problem spot in her lawn for approximately 6 months. There were no plant pathogens or insect-related problems found associated with the turf sample submitted to the lab. However, we were able to detect high levels of polyaromatic hydrocarbons in the soil due to a leak in a buried natural gas line.
Intentional fuel spill in the landscape (view images)
A homeowner noticed significant damage to his landscape over a span of a few months. He noticed dead, irregular-shaped areas in the lawn; needles of a spruce tree that quickly browned and quickly dropped; maple leaves that wilted and quickly dropped; death of two red bud trees; and several other plants in the landscape with obvious injury symptoms. After much investigation, polyaromatic hydrocarbons were detected at extreme levels in soil collected from the problem spots. This diagnostic result, along with patterns of injury in the landscape and a videotape of the homeowner’s neighbor discarding cups of liquid in these areas suggest an intentional exposure of some type of fuel.
Pendimethalin injury of new grass seedlings (view images)
A homeowner complained that she could not get grass seed established in areas where new top soil was spread. She believed the top soil purchased from a local landscape supplier contained some type of contaminant. Soil submitted to the lab in a plastic bag contained a subtle yellow tint. The homeowner claimed she had spread a regular fertilizer before seeding the grass mixture. We suspected, however, that she mistakenly or unknowingly applied a fertilizer containing a “crabgrass preventer.” Pendimethalin was detected in the soil, which is a very common herbicide used in products sold as “crabgrass preventors.” Pendimethalin is safe on established grasses but can injure or kill seedling grasses.