Continual Mowing Can Strengthen Poisonous Weed Rather Than Tame It
A noxious weed that produces toxins harmful to humans and steal nutrients from crops can actually be strengthened by an act aiming to destroy it. Researchers with the Arkansas Agricultural Experiment Station have observed in a series of studies that Solanum elaeagnifolium, also known as silverleaf nightshade, increases its defenses when mowed. The plant was found to grow deeper roots, more spines to defend the flowers from caterpillars, more toxicity in the flowers and more robust seeds with staggered germination times to increase the chances of survival. The studies offer insights into how plants, especially noxious weeds, respond to human disturbance.
The Problem
Solanum elaeagnifolium, also known as silverleaf nightshade, is a common weed in arid areas like Texas, and relatives of the plant are native to Arkansas. The noxious weed produces toxins harmful to humans, making it a desirable target for removal as part of routine property maintenance. The unwanted plant can infest fields and deplete them of valuable nutrients needed for crop growth. Its spine is spiked, and its berries are poisonous.
One common method for removal is by mowing the weed down. However, recent research by scientists with the Arkansas Agricultural Experiment Station shows this may not be the best practice. Those who frequently mow the weed may actually be making it stronger.
The Work
Rupesh Kariyat, associate professor of entomology and plant pathology, worked with graduate students at the University of Texas Rio Grande Valley to develop a study that would monitor mowed, unmowed and frequently mowed silverleaf nightshade fields in and near Edinburg, Texas. They investigated how mowing impacts the plant’s physiology and its interactions with the insects that feed on it.
The Results
Testing revealed that as mowing increased, so did the plant’s ability to avoid destruction from insects. Plants developed more spikes as a defense mechanism, and their flowers became more toxic to caterpillars, making predators less inclined to attack it. The plant’s taproot also grew down further, nearly 5 feet deep. The plants also utilized “staggered” germination to allow some groups of seeds to germinate faster than others, generating long-term survival.
The Value
The study provides insights into the defensive capabilities of plants when pitted against human disturbance. With this new knowledge, property owners may be able to craft more informed, effective management plans for the universal practice of mowing. Having a better understanding of the ecology and biology of plant species and the other species that interact with those plants may also prompt further studies by weed scientists on best management practices.
Read the Research
Continuous Mowing Differentially Affects Floral Defenses in the Noxious and Invasive Weed Solanum elaeagnifolium in its Native Range
Scientific Reports
Volume 14, Article Number 8133 (2024)
https://doi.org/10.1038/s41598-024-58672-w
Local Adaptation to Continuous Mowing Makes the Noxious Weed Solanum elaeagnifolium a Superweed Candidate by Improving Fitness and Defense Traits
Scientific Reports
Volume 11, Article Number 6634 (2021)
https://doi.org/10.1038/s41598-021-85789-z
About the Researcher
Rupesh Kariyat
Associate Professor of Entomology and Plant Pathology
Ph.D. in Plant Biology, The Pennsylvania State University, University Park
M.S. in Agronomy, University of Wyoming, Laramie
B.S. in Agricultural Sciences, Kerala Agricultural University, India
Alejandro Vasquez
Senior Graduate Assistant
Ph.D. (in progress) in Entomology, University of Arkansas, Fayetteville
M.S. in Biology, General, University of Texas Rio Grande Valley
B.S. in Biology, General, University of Texas Rio Grande Valley
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