Commentary by Carrie Madren
Crowning summer cookouts, ears of local corn are hot weather staples. Roasted on a grill, splashed with butter and sprinkled in salt and pepper—and in Chesapeake Country, Old Bay, of course—corn makes barbecues complete.
This essential summer side dish may be in danger, however, if global warming continues to incrementally warm our Mid-Atlantic region. Corn, which prefers growing at about 50 to 86 degrees Fahrenheit, will feel the effects from hotter temperatures and more destructive storms, pests, weeds, diseases and ozone pollution.
The range of predicted warming is wide: climate change models predict a U.S. warming of anywhere from two to 10 degrees in the next 100 years. Worldwide, the 10 warmest years on record have fallen within the last 12 years. More sweltering 90-plus-degree days could force a change in the way farmers grow corn, according to a report by Environment Maryland called Hotter Fields, Lower Yields.
In mid-summer, growers hope for cooler weather because of a roughly two-week window when pollination occurs. If temperatures are searing, that can hinder kernel development, making the corn less tasty and robust. Currently, Pennsylvania summers are ideal for growing sweet corn, and these days, Pennsylvania only experiences five to 10 August days when the temperature exceeds 90 degrees, according to a report by the Union of Concerned Scientists. But by 2100, under the higher-emissions scenario, most of August (as well as July) in Pennsylvania is projected to exceed 90 degrees. Further south, days would be even warmer.
Among climate change's curses is drought. Increased drought will mean more irrigation, especially where sandy soils (such as in Maryland's Eastern Shore) fail to hold water, says Robert Kratochvil, associate professor and extension specialist at the University of Maryland. But, increase irrigation too much and water tables can run low, creating water shortages.
Entomologists predict that warmer temperatures will expand insect ranges, and increase reproduction rates and overwintering success. As weed and pest ranges move north, farmers will have to apply more pesticides more frequently to keep corn yields up - meaning a higher financial and environmental cost.
One sweet corn disease that farmer's fear is Stewart's wilt, a disease transmitted by the corn flea beetle. Cold winters typically kill off populations of the beetles, but warmer winters may bring increasing severity of Stewart's wilt. Farmers can choose to plant disease resistant varieties of corn, but these varieties may be different in taste, texture and appearance than our favorite summertime staple. Another pest, corn earworm, may also be able to overwinter in a larger, more northern range.
According to the New York Agricultural Extension's review of several studies, New York conditions currently require zero to five insecticide applications against lepidopteron insect pests to produce marketable sweet corn; Maryland and Delaware conditions require four to eight insecticide applications; for comparison, Florida conditions require 15 to 32 applications.
If growing conditions worsen, it could cost farmers - and us corn lovers - millions. Climate changes since 1981 have already cost corn growers worldwide about $1.2 billion per year, according Environment Maryland's report, which estimates that global warming will cost corn growers in the United States at least another $1.4 billion per year as temperatures continue to climb. In Virginia, that cost is projected at $5 million. Maryland, fares worse with an estimated $6.2 million loss, and Pennsylvania stands to lose about twice as much at $13 million - about New York's estimated loss of $12 million.
Fickle weather has always challenged farmers, but climate change may mean growers must find new ways to adapt and adjust by investing in irrigation, using no-till practices (which help lock in moisture, and help sequester more carbon) and employing other techniques. Increasingly, if summer temperatures regularly soar, farmers will buy varieties of corn selectively bred for drought and pest intolerance, according to Kratochvil. Farmers who make the best use of the basics of integrated pest management such as field monitoring, pest forecasting, recordkeeping and choosing economically and environmentally sound control measures will be the most successful in dealing with climate change's wrath, according to the New York Agricultural Extension.
No one knows how high average temperatures will rise in the next century, but the Intergovernmental Panel on Climate Change forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century; a 2009 report by the United Nations Environment Program predicts a 6.3-degree Fahrenheit rise in the same time frame.
A temperature increase of even four or five degrees would have a significant effect on the way corn is grown and where it's grown, says Wade Thomason, assistant professor of grain crops in the extension service at Virginia Tech. Such an effect could mean a shift in crops, among other agricultural adjustments.
For now, farmers are focusing on short-term survival, planting and tending to each year's crops in the midst of unknown annual variables such as market and weather. In the meantime, scientists and researchers are sounding loud alarms in response to climate change. As temperatures incrementally rise, the future of our corn-on-the-cob and the farmers who raise it depends on our collective actions.
If our lawmakers take climate change seriously and force energy conservation and development of technologies that cut carbon and greenhouse gases, then our warming may be a blip; keep on spewing greenhouse gases, and farmers of the next generation may have to adapt and adjust - at a higher cost.
Carrie Madren writes about environmental issues, Chesapeake life, and sustainable living. She lives in Olney, Maryland. Distributed by Bay Journal News Service.