Have you been wondering why the leaves in College Park this autumn are looking a little less, well, autumnal than in previous years?

There’s a reason for that: The warming planet is messing with the natural processes that normally cause leaves to take on red and orange colors around this time of year. 

Trees aren’t the only types of plants climate change is affecting in Maryland. But at the University of Maryland, researchers are contributing to efforts to alleviate the effects that rising sea levels, global warming and an increase in severe storms are having on the state’s vegetation.

According to John Erwin, chair of the plant science and landscape architecture department, the mean temperature in Maryland has increased 1.8 degrees Fahrenheit since 1895. While that may not sound like much, Erwin said a one degree increase during only the daytime has been shown to decrease crop yield by 2.5 to 16 percent.

The effect of global warming on crop growth is one of the focuses of Erwin’s research lab. Erwin’s lab studies both the molecular underpinnings of how global warming affects crop growth and whether certain varieties of plants do better at surviving extreme heat events.

“This is an extremely wet year in Maryland. And it’s been getting wetter and it’s been getting hotter,” he said.

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Erwin’s lab has shown that exposing a plant to 95 degree Fahrenheit conditions for just two hours decreases its rate of photosynthesis for at least three days. His lab has also found this decrease is associated with changes in the levels of a certain kind of plant hormone. The lab is also currently examining other genetic changes related to the decrease.

Additionally, Erwin’s lab has found that some varieties of tomatoes are better at responding to these heat challenges, making them potentially better for farmers in this area to grow. 

Climate change has also increased the rate at which some infectious diseases affect plants in the state. 

At the university’s Plant Diagnostic Laboratory, researchers receive samples of diseased plants from all over the state and figure out what caused the plants to become sick. For instance, Karen Rane, the lab’s director, said a specific fungus recently caused farmers in St. Mary’s County to lose their pumpkin crops ahead of Halloween. 

According to Rane, excessive or repeated rainfall promotes the spread of this fungal infection. Although farmers can apply pesticides to kill the fungus and protect their plants, farmers were not able to apply enough pesticide fast enough to prevent the spread of this infection.

“These extremes, they’re hard to plan for, and the scientists tell us that we see more and more of those as climate change progresses,” Rane said.

Rising sea levels are also affecting the Eastern Shore farming community by causing more saltwater to mix with freshwater supplies, worsening the soil quality. The major crops of the Eastern Shore have historically been corn, soybeans, winter wheat and rye. However, all of these crops have lower yields when the soil becomes saltier, according to Kate Tully, a professor in the plant science and landscape architecture department.

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“On the Eastern Shore of Maryland, it’s just sort of this perfect storm — literally —  you’ve got  big storms that come through and then bring high tides and storm surges,” Tully said.

Tully’s research, funded in part by the U.S. Agriculture Department, aims to help develop trajectories for when farming areas might be affected by saltwater and to develop interventions — identifying financially-feasible crops that are more resistant to salty soil, for instance — to help farmers succeed despite the changing environment. 

Tully said malting barley, used by breweries for beer, and sorghum, a grain used as feed for the chicken industry that contributes significantly to the Eastern Shore’s economy, are two crops her lab is currently studying as potential replacements.

Tully said her research has piqued the interest of the state government and investors that provide loans to farms in the area. On Monday, Gov. Larry Hogan announced a new initiative that will provide funding to state farmers who were financially affected by the COVID-19 pandemic.

Tully said the area her research explores also hits on an effect of the changing climate that may be more tangible and easier to grasp than others.

“I think, in many cases, climate change is a little bit nebulous and it’s hard to put your finger on,” she said, “And it’s like ‘Look, you can’t grow anything here.’”