Pests and Diseases Cause Worldwide Damage to Crops

Pests and Pathogens Place Global Burden on Major Food Crops

By Pam Kan-Rice, UC Agriculture & Natural Resources

Scientists survey crop health experts in 67 countries and find large crop losses caused by pests and diseases

Farmers know they lose crops to pests and plant diseases, but scientists have found that on a global scale, pathogens and pests are reducing crop yields for five major food crops by 10 percent to 40 percent, according to a report by a UC Agriculture and Natural Resources scientist and other members of the International Society for Plant Pathology. Wheat, rice, maize, soybean, and potato yields are reduced by pathogens and animal pests, including insects, scientists found in a global survey of crop health experts.

At a global scale, pathogens and pests are causing wheat losses of 10 percent to 28 percent, rice losses of 25 percent to 41 percent, maize losses of 20 percent to 41 percent, potato losses of 8 percent to 21 percent, and soybean losses of 11 percent to 32 percent, according to the study, published in the journal Nature, Ecology & Evolution.

Viruses and viroids, bacteria, fungi and oomycetes, nematodes, arthropods, molluscs, vertebrates, and parasitic plants are among the factors working against farmers.

Food loss

“We are losing a significant amount of food on a global scale to pests and diseases at a time when we must increase food production to feed a growing population,” said co-author Neil McRoberts, co-leader of UC ANR’s Sustainable Food Systems Strategic Initiative and Agricultural Experiment Station researcher and professor in the Department of Plant Pathology at UC Davis.

While plant diseases and pests are widely considered an important cause of crop losses, and sometimes a threat to the food supply, precise figures on these crop losses are difficult to produce.

“One reason is because pathogens and pests have co-evolved with crops over millennia in the human-made agricultural systems,” write the authors on the study’s website, globalcrophealth.org.  “As a result, their effects in agriculture are very hard to disentangle from the complex web of interactions within cropping systems. Also, the sheer number and diversity of plant diseases and pests makes quantification of losses on an individual pathogen or pest basis, for each of the many cultivated crops, a daunting task.”

“We conducted a global survey of crop protection experts on the impacts of pests and plant diseases on the yields of five of the world’s most important carbohydrate staple crops and are reporting the results,” McRoberts said. “This is a major achievement and a real step forward in being able to accurately assess the impact of pests and plant diseases on crop production.”

The researchers surveyed several thousand crop health experts on five major food crops – wheat, rice, maize, soybean, and potato – in 67 countries.

“We chose these five crops since together they provide about 50 percent of the global human calorie intake,” the authors wrote on the website.

The 67 countries grow 84 percent of the global production of wheat, rice, maize, soybean and potato.

Top pests and diseases

The study identified 137 individual pathogens and pests that attack the crops, with very large variation in the amount of crop loss they caused.

For wheat, leaf rust, Fusarium head blight/scab, tritici blotch, stripe rust, spot blotch, tan spot, aphids, and powdery mildew caused losses higher than 1 percent globally.

In rice, sheath blight, stem borers, blast, brown spot, bacterial blight, leaf folder, and brown plant hopper did the most damage.

In maize, Fusarium and Gibberella stalk rots, fall armyworm, northern leaf blight, Fusarium and Gibberella ear rots, anthracnose stalk rot and southern rust caused the most loss globally.

In potatoes, late blight, brown rot, early blight, and cyst nematode did the most harm.

In soybeans, cyst nematode, white mold, soybean rust, Cercospora leaf blight, brown spot, charcoal rot, and root knot nematodes caused global losses higher than 1 percent.

Food-security “hotspots”

The study estimates the losses to individual plant diseases and pests for these crops globally, as well as in several global food-security “hotspots.” These hotspots are critical sources in the global food system: Northwest Europe, the plains of the U.S. Midwest and Southern Canada, Southern Brazil and Argentina, the Indo-Gangetic Plains of South Asia, the plains of China, Southeast Asia, and sub-Saharan Africa.

“Our results highlight differences in impacts among crop pathogens and pests and among food security hotspots,” McRoberts said. “But we also show that the highest losses appear associated with food-deficit regions with fast-growing populations, and frequently with emerging or re-emerging pests and diseases.”

“For chronic pathogens and pests, we need to redouble our efforts to deliver more efficient and sustainable management tools, such as resistant varieties,” McRoberts said. “For emerging or re-emerging pathogens and pests, urgent action is needed to contain them and generate longer term solutions.”

The website globalcrophealth.org features maps showing how many people responded to the survey across different regions of the world.

In addition to McRoberts, the research team included lead author Serge Savary, chair of the ISPP Committee on Crop Loss; epidemiologists Paul Esker at Pennsylvania State University and Sarah Pethybridge at Cornell University; Laetitia Willocquet at the French National Institute for Agricultural Research in Toulouse, France; and Andy Nelson at the University of Twente in The Netherlands. 

UC Agriculture and Natural Resources researchers and educators draw on local expertise to conduct agricultural, environmental, economic, youth development and nutrition research that helps California thrive. Learn more at ucanr.edu.

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Healthy Soils Initiative Looks at Cover Crops

Cover Crops Between Annual Veg Crops Studied

 By Patrick Cavanaugh, Editor

Research is under way to determine if using cover crops between two annual vegetable crops will improve the soil for future crops. It’s all part of the California Department of Food and Ag Healthy Soils Program—a statewide project.

Amber Vinchesi is a UCANR Vegetable Crops Farm Advisor in Colusa, Sutter and Yuba counties. She works mainly with processing tomatoes but also with growers farming vegetables for seed as well as fresh market vegetables such as honeydew and cantaloupe melons.

Vinchesi is collaborating with California’s Healthy Soils Initiative, a partnership of state agencies and departments led by the CDFA Healthy Soils Project. It’s a combination of innovative farm and land management practices that may contribute to building adequate soil organic matter that may increase carbon sequestration and reduce overall greenhouse gases.

“We have three sites, and the site that I’m working on is focused on winter cover crops between crops such as wheat, tomato or corn, to improve soil health,” said Vinchesi, who is being assisted by her colleague Sarah Light, the agronomy advisor in Sutter, Yuba, and Colusa counties

Other Healthy Soil sites are located in the Delta area, and overseen by Michelle Leinfelder-Miles, UCANR Delta Crops Resource Management Advisor in San Joaquin County. Brenna Aegerter, a UCANR Vegetable Crops Farm Advisor also in San Joaquin County, is working with Leinfelder-Miles. Additionally, Scott Stoddard a UCANR Vegetable Crops Farm Advisor in Merced County has a site.

The cover crop will be vetch, a legume.

“We hope that it will put nitrogen and biomass into the soil,” Vinchesi said. “We’re not sure what the results will be, but we hope it will help with aggregate stability, water infiltration, and even reduce weed density.”

She noted that the trial, which is in the first year of a three-year project, will include two different seeding rates, a high and low rate, and then an untreated control where there’s no cover crop.

“And we’ll do soil testing to see how things change in the soil over time,” she explained.

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Ag Day 2015: A beautiful day to be a farmer

California’s agricultural community gathered yesterday on the west steps of the State Capitol to show, see and share the bounty of our state’s farmers and ranchers. It was a perfect day for such a celebration (although to be perfectly honest, the farmers would have preferred rain). In keeping with the United Nations’ declaration of 2015 as the International Year of Soils, the theme for Ag Day this year was “Breaking New Ground.”

Special thanks to the California Department of Food and Agriculture’s partners in organizing Ag Day, the California Women for Agriculture and the California Foundation for Agriculture in the Classroom.  Thanks also go to our emcee, Kitty O’Neal of KFBK Newsradio, as well as event sponsors the California Egg Farmers, the California Alpaca Breeders Association, the California Farm Bureau Federation, California Grown, the California State Board of Equalization, the California Strawberry Commission, the Farmer Veteran Coalition, Got Milk?, John Deere, the Kubota Tractor Company-California, and the University of California Division of Agriculture and Natural Resources.

 

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UC leads a long tradition of environmental stewardship in California

By  Brook Gamble, Community Education Specialist, UC ANR California Naturalist Program, Hopland Research & Extension Center

Featured Photo:  Jeannette Warnert

 

Stewardship: \ˈstü-ərd-ˌship: the activity or job of protecting and being responsible for something.

In 1862 the Morrill Act was passed to support and maintain colleges of agriculture and mechanical arts, including a later provision that included the donation of public land. As one of the first land grant Universities, the University of California was well positioned to manage agricultural extension across the state as part of the Smith Lever Act of 1915. Today, many people think of California agriculture as strawberries, broccoli and rice; but it is livestock and forestry that dominated California working landscapes in those early days.

Farmer seeks assistance from UCCE farm advisor on the running board of a historic UC Cooperative Extension vehicle.
Farmer seeks assistance from UCCE farm advisor on the running board of a historic UC Cooperative Extension vehicle.

Research and extension efforts to improve forestry practices and range production throughout California have evolved over time. Research questions gradually changed over the last 100 years from a “how can we economically produce more” perspective to how can rangeland management practices improve ecosystem composition and function? How can extension programs be employed to educate stakeholders and help land managers implement change? How can we conserve working landscapes for biodiversity conservation in a period of rapid development? How can we assess and monitor management effectiveness?

This year, the University of California Division of Agriculture and Natural Resources celebrates 100 years of UC Cooperative Extension serving as a research and outreach partner in communities throughout California. For an interesting read on this rich history and the evolution of UC rangeland management perspectives, see M. George, and W. J. Clawson’s The History of UC RangelandExtension, Research, and Teaching: A Perspective (2014). Additionally, UC ANR California Rangelands Website includes a free Annual Rangeland E-book; current project descriptions, publications, and online learning modules: http://californiarangeland.ucdavis.edu/.

Maintaining and improving environmental quality on public and private land requires an informed strategy that encourages stewardship by land owners and community members. In present times, we face the challenges of managing land in the face of growing population, drought, invasive species, and climate change, just to name a few forces of global change. Out of necessity, our broader perspective on land management has shifted to one of “ecosystem stewardship” which is defined as a strategy to respond to and shape social-ecological systems under conditions of uncertainty and change to sustain the supply and opportunities for use of ecosystem services to support human well-being (Chapin et al. 2010). The stewardship framework focuses on the dynamics of ecological change and assesses management options that may influence the path or rate of that change.

Using an ecosystem stewardship framework, the UC ANR’s California Naturalist Program is building astatewide network of environmental stewards. The program is designed to introduce the public, teachers, interpreters, docents, green collar workers, natural resource managers, and budding scientists to the wonders of our unique ecology and engage these individuals in the stewardship of California’s natural communities.

Tejon Ranch Conservancy California Naturalists help with a pipe capping project to keep small animals and birds from getting trapped (Photo: Scot Pipkin)
Tejon Ranch Conservancy California Naturalists help with a
pipe capping project to keep small animals and birds from
getting trapped (Photo: Scot Pipkin)

The California Naturalist Program uses a science curriculum which includeschapters in forest, woodland, and range resources and management, geology, climate, water, wildlife, and plants. Experiential learning and service projects instill a deep appreciation for the natural communities of the state and serve to engage people in natural resource conservation.

Land management is the focus of many of the partnering organizations that offer the California Naturalist Program. For example, land conservancies and preserves are involved including, Tejon Ranch Conservancy, at 270,000 acres the largest contiguous private ranch in California; Pepperwood Preserve, a private rangeland preserve dedicated to conservation science in the Northern SF Bay Area; UC Berkeley’s Sagehen Creek Field Station, a forested research station in the Sierra; UC Hopland Research & Extension Center, a rangeland research and education facility in California’s north coast region; and the Sierra Foothill Conservancy, a non-profit land trust in the Western Sierra Nevada including Fresno, Madera, eastern Merced, and Mariposa counties. Land trusts are increasingly responsible for conserving working landscapes and open space across the state and often rely on a trained volunteer corps to steward these valuable landscapes. UC ANR is pleased to advance training opportunities for those actively managing these lands.

California Naturalists trained at these locations and more are involved in ecosystem stewardship, rangeland management, watershed restoration, and helping outdoor education programs that benefit the environment and people of all ages. Naturalists have donated over 13,000 hours of in state service in the last three years. These types of stewardship opportunities are essential for the active adaptive management that both public and private lands need to ensure resilience and continue to provide ecosystem services that we all rely on. These trained environmental stewards are an important part of this growing community of practice who not only steward land but also pass on critical knowledge about California’s natural and managed ecosystems.

With Special Thanks to Brook Gamble.

 

UC Berkeley’s Sagehen Creek Field Station

 

California Naturalists examine watershed maps

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