Climate change may reduce yields of crops like corn and soybeans, but it can also give some plants an edge.
That’s one of the takeaways of a recent study of tall goldenrod, a common wildflower that runs rampant in fields across its native range in North America and other parts of the world where it has been introduced.
Many goldenrod plants are pocked by tumorlike growths, called galls, that form when insects trick the plant into building a nursery for their larvae. New research suggests that climate change can offset some of the harmful effects of these insect squatters — effects that would otherwise help keep goldenrod plants in check.
The findings were published April 4in the journal Oecologia.
You may have spotted tall goldenrod especially in late summer, when it carpets fields and roadsides with thick stands of feathery yellow blooms.
What you might not notice are the insect inhabitants hiding within. Goldenrod is host to dozens of insects, many of which use the plant to feed and protect their young.
The researchers studied one of them, a tiny fly called the goldenrod bunch gall midge. Females lay their eggs in leaf buds, which stops the plant from growing normally and triggers it to make a dense cluster of leaves around the egg. The insect hatches and lives within this botanical fortress, chomping away at the plant until it eventually emerges to continue its life cycle.
“It basically triggers the plant to make a tumor around its growing babies,” said first author Emily Parker , who conducted the research as an undergraduate at Michigan State University.
Parker and a team led by professor Phoebe Zarnetske of MSU’s Ecology, Evolution and Behavior program wanted to know how goldenrod and its insect guests might fare as weather patterns continue to shift.
While previous studies have looked at how plants are impacted by individual stresses such heat or herbivory, what happens in nature when multiple stresses coincide is less clear.
“You can’t just look at species individually to understand how they will respond to climate change,” Zarnetske said. “You need to keep in mind the climate responses of their friends and enemies too.”
So the researchers conducted an experiment at the Kellogg Biological Station Long-Term Ecological Research Site in southwestern Michigan.
Over two years, they simulated possible future climate in the Michigan grassland. They covered some plots with a plexiglass roof to block rain from reaching the plants and mimic summertime drought. And they used open-topped chambers with clear plastic walls as mini greenhouses, to trap heat and warm the air around the goldenrod.
Their results show that goldenrod plants aren’t impervious to their hungry houseguests.
“Galling insects pull nutrients away from the plant and reduce its reproductive output,” said senior author Zarnetske, who is also a professor in MSU’s Integrative Biology department.
But while galling insects can be hard on goldenrod, the findings revealed that warming can help level the playing field, and even give infested plants an advantage over their unaffected counterparts.
Under ambient conditions, for example, gall-infested goldenrod stems produced seeds that were 0.2 grams punier than unaffected plants, and they were 24% less likely to make seeds at all. But these relative disadvantages vanished with warming, and with warming and drought combined.
Galls can also cause stunted growth, they found. Under ambient conditions, stems with galls were roughly seven centimeters shorter than gall-free plants. But warming boosted their height until they outgrew their non-galled counterparts.
Climate change could benefit gall-infested plants in other ways too: Under ambient conditions, plants with and without galls both grew to be equally hefty. But under warmed conditions, galled plants grew 16% heftier than those without galls, and the combined effect of warming and drought boosted their biomass above the rest by 39%.
“Warming appears to offset the negative effects of galling,” said co-author Kara Dobson , who conducted the work as a Ph.D. student in Zarnetske’s Spatial and Community Ecology Lab (SpaCE Lab)
For their part, the gall-making insects appeared to be unaffected.
Zarnetske said the results aren’t entirely surprising. Previous work by her team shows that warming can stimulate plant growth in goldenrod and other species , due to longer growing seasons and increased enzyme activity.
Tall goldenrod is an opportunist: once it gains a foothold it can spread quickly by way of seeds and underground stems that can sprout new shoots. It also produces chemicals that hinder the growth of nearby plants.
It’s these abilities that often let goldenrod carpet fields and meadows, where it chokes out other species.
“Goldenrod takes over landscapes,” Dobson said. “If you see it, it's everywhere, basically.”
Seasonal allergy sufferers can rest assured, she added. Although goldenrods are frequently blamed for hay fever, the culprit for your itchy eyes and runny nose is another plant called ragweed.
At some point, the combination of changing weather patterns, hungry insects and other stressors “could become too much even for dominant species” like goldenrod, Zarnetske added.
But for now, the results suggest this aggressive plant species may continue to muscle out other plants in a warmer world.
“Which may mean goldenrod can go even crazier,” Parker said.
This research was supported by the National Science Foundation (DEB 2224712, DGE 184-8739, DGE 1828149), the Kellogg Biological Station, Michigan State University and MSU’s AgBioResearch.
CITATION: "Climate warming and drought modify galling effects on tall goldenrod," Emily G. Parker, Kara C. Dobson, Moriah L. Young, Mark D. Hammond, Phoebe L. Zarnetske. Oecologia, April 4, 2026. DOI: 10.1007/s00442-026-05889-3
Oecologia
Experimental study
Not applicable
Climate warming and drought modify galling effects on tall goldenrod
4-Apr-2026