University of California, Division of Agricultural and Natural Resources Archives - Page 7 of 15

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.

California Ag Today2021-05-12T11:05:06-07:00February 11th, 2019|

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.

California Ag Today2021-05-12T11:05:06-07:00January 29th, 2019|

Tomato Spotted Wilt Virus Fights Back

New Strain Creates Challenges

By Mikenzi Meyers, Associate Editor

A new strain of the Tomato Spotted Wilt Virus has created a challenge among vegetable growers, making integrated pest management, or IPM, increasingly critical. Bob Gilbertson, plant pathologist at UC Davis, has insight and advice as to how farmers should tackle this new strain.

“The first thing is to know what’s out in your field. And there’s a good diagnostic test for curly top, spotted wilt, alfalfa mosaic, and other viruses,” Gilbertson said.

Bob Gilbertson

After the virus is confirmed, he encourages growers to explore their options of treatment. Prior to the new spotted wilt virus strain, growers could turn to the SW-5 resistance gene to cure their field. Unfortunately, Gilbertson explained, the new strain actually breaks that resistance, which is where IPM becomes even more important.

In the future, Gilbertson hopes to find additional resistance genes to break the new strain. Until that time comes, he wants to use good IPM to manage it.

Gilbertson further added, “Increased sanitation, removing overwintering hosts, weeds, and bridge crops like lettuce, and then timing the applications of thrips management better, to slow down the appearance of adult thrips that carry the virus,” are all examples of good IPM.

California Ag Today2021-05-12T11:01:50-07:00January 18th, 2019|

Jeff Mitchell: Conservation No-Till Is One Option For Water Conservation

Jeff Mitchell Has Devoted Career to Conservation No-Till

By Patrick Cavanaugh, Editor

Jeff Mitchell is a Cropping Systems Specialist at UC Davis, based at the Kearney Agricultural Research and Extension Center in Parlier. He has devoted 19 years to improving nitrogen and water use efficiencies in food, feed, fuel and fiber in no-till cropping systems.

Mitchell’s passion helped found Conservation Agriculture Systems Innovation Center (CASI) in 1998. CASI operates under the auspices of the University of California Division of Agriculture & Natural Resources.

His no-till research focuses on soil quality management and potential roles of cover crops and compost in intensive row crop production systems, and the use of cover crop mulches as a means of conserving soil water, suppressing weeds and increasing organic matter in no-till production systems.

He often cites a book called Plowman’s Folly by Edward H. Faulkner, published following the ruinous Dust Bowl. Faulkner dropped an agricultural bombshell when he blamed the then universally used moldboard plow for disastrous pillage of the soil.

This book is the 11th all-time cited, read, or acknowledged a piece of work related to the soil in the history of scientific literature.

“When it was written in 1943, it caused great arguments. The government got involved with the USDA trying to defend the science of the day,” Mitchell said.

The reason the book was so controversial is that it proved that there had been no scientific reason for plowing.

“He was getting in people’s faces by saying, ‘This might not be the way to do it,’ ” Mitchell said. “Faulkner’s stance was embroiling people.”

Mitchell’s work centers on conservation, no-till production of vegetable and cotton crops. The idea is to plant in the crops’ residue, which builds up a rather thick layer of mulch on the bed—leading to reduced water and nitrogen, as well as minimizing weeds.

Mitchell cited several growers in the Midwest and in California that are successfully practicing conservation no-till agriculture. And there is much more recent attention on soils with the Healthy Soils Program (HSP)—stemming from the California Healthy Soils Initiative, a collaboration of state agencies and departments to promote the development of healthy soils on California’s farmlands and ranch lands.

Jeff Mitchell describing the no-till soil that he has been working with for 19 years.

The HSP has two components: the HSP Incentives Program and the HSP Demonstration Projects. The HSP Incentives Program provides financial assistance for the implementation of conservation management that improves soil health, sequester carbon and reduce greenhouse gas (GHG) emissions. The HSP Demonstration Projects showcase California farmers’ and ranchers’ implementation of HSP practices.

“The principles that we are pursuing are allowing growers to keep excellent yields and maybe increase sometimes, cut out some inputs like fertilizers to save money, and to do it with less—less disturbance and fewer operations,” Mitchell explained. “None of this is new. It was 90 years ago when the Natural Resources Conservation Service established the principles of good soil management

Healthy soil holds more water (by binding it to organic matter), and loses less water to runoff and evaporation.
Organic matter builds as tillage declines and plants and residue cover the soil. Organic matter holds 18 to 20 times its weight in water and recycles nutrients for plants to use.
One percent of organic matter in the top six inches of soil would hold approximately 27,000 gallons of water per acre!
Most farmers can increase their soil organic matter in three to 10 years if they are motivated about adopting conservation practices to achieve this goal.

“In 2013, a group of 30 farmers came up with a similar kind of a list,” Mitchell said. “They brainstormed on what would be good soil management, and they came up [with] feed the soil organic matter, reduced disturbance, increased diversity—the same as the NRCS list.”

Mitchell cited a newspaper article published in 1931. “People were finding benefits of cover crops in San Joaquin Valley farming systems. Now with the Healthy Soils Initiative, farmers are trying these techniques and evaluating it. There’s a lot of activity that is going on at many different sites in the state.”

Mitchell’s work at the West Side Research and Extension Center in Five Points on the conservation no-till approach has been with scientific protocol and replicated over 19 years.

“Initially, we would have several systems. In the no-till system, rotations of cotton, transplanted tomato, and a forage crops would grow back to back in a no-till system,” he explained. “Each crop would be planted in the residue of the previous crop. Over the years, the no-till plots have grey residue from last year plantings.”

A cover crop has been planted in a no-till field of cotton that followed tomatoes.

“Cover crops can also be part of the no-till system, which over the last 18 years have added 34 tons of biomass, which includes 13 tons of carbon per acre to the system, which is a good thing,” Mitchell said. “It adds fuel to the soil biology, but it’s not perfect.”

“My supposition would be that growing cover crops is more completed than people think. I have been at meetings where growers say: ‘are you kidding, I’m not going to grow cover crops because I do not have the water,’” Mitchell noted.

He said he understands the situation in not having enough water. But he explained, “In the winter time, yes there will be evaporation from the soil service every day. Radiation is beating down, and there will be evaporation.”

Evaporation in the cover crop field could be more nuanced. Maybe because the soil surface is shaded out, which would cool the soil, there may not be that much evaporation. The cover crops may increase infiltration of water in the ground, instead of it ponding on the soil surface.

“Yes, there will be some inevitable use of water by growing vegetation in the field in the winter, but it could be less than we think,” Mitchell said.

Mitchell then showed two large aluminum pans of soil. One showed soil dug up in an open field that has been tilled. The other container is soil with crop residue from the non-tilled plots.

He takes a handful of each and drops them into two individual gallon jars within an open metal grid with a few inches of water. This what Mitchell sees every time he does this. The large jar with tilled soil breaks up rapidly with soil particles dropping to the bottom. Within the no-tilled soil jar, the chunk of soil is very stable, with no soil particles breaking off.

“One thing that we are not doing now is looking at the potential benefits of these no-till systems and practices for conserving water and making better use of water that has been achieved in other areas of the world such as South America and the Great Plains and other regions of the United States. They do not have irrigation systems that California has; they have to wait for rainfall.”

“When we do the no-tilled system with lots of residue from back-to-back crops, with cover crops and with no disturbances, you may be able to keep 4 to 5 inches of water in the soil each year compared to a tilled crop.

More information on the Conservation No-Till system can be found here.

California Ag Today2021-05-12T11:05:07-07:00December 10th, 2018|

Tea: More Than Just a Drink

Rich American History Around Tea

By Mikenzi Meyers, Associate Editor

As the weather starts to get colder in California, nothing sounds better than a cup of warm tea on a chilly day. When reaching for what might be your favorite winter drink, Jeff Dahlberg, director of the Kearney Ag Research and Extension Center, urges you to think about the rich history behind it.

Dahlberg explained that, “Americans have been drinking tea for a long time. Back in the 1700s, as I understand it, there used to be tea shops everywhere in the U.S.”

Jeff Dahlberg

He further emphasized the importance of truly educating yourself on the drink, which will only add to your ability to select the teas that best suit your pallet.

Even better, Dalhberg believes that first-class teas can be grown right here in California—an opportunity that the Global Tea Initiative in Davis is already looking into.

“Bottom line, we can actually grow pretty high-quality, high-yielding teas here in the state, and the folks at Davis are really excited about that,” he said.

For more information on the Global Tea Initiative, visit GlobalTea.UCDavis.Edu.

For more information on the Kearney Ag Research and Extension Center, visit their website at: kare.ucanr.edu

California Ag Today2018-11-29T16:21:28-08:00November 29th, 2018|

Sorghum Not Well Known in the U.S.

Sorghum Used in Different Ways in the World

By Mikenzi Meyers, Associate Editor

The Kearney Ag Research and Extension Center is currently doing extensive drought tolerant research on sorghum, a plant with a variety of uses. Jeff Dahlberg, director of the Kearny Ag Research and Extension Center in Parlier, knows the complexity of the plant, and the need to educate farmers about it.

Sorghum is used for humans and animal feed around the world.

“The challenge here is that nobody knows very much about sorghum, and I have to kind of retrain our nutrition people about how to use it properly, and how to treat it so that you can get the most use out of it,” Dahlberg said.

He further added that in most parts of the world sorghum is primarily used for human consumption, however, here in the United States, we use it for animal feed. Dahlberg has been looking into introducing the plant to California dairies as an alternative for forages that require more water.

Even though producers that currently use sorghum are pleased with the results, a new problem has been brought to Dahlberg’s attention.

“We had this insect show up called the Sugarcane Aphid. It can be controlled, but it takes a bit of management,” he explained.

Although the aphid presents challenges, Dahlberg knows that with the proper training the issue can be resolved.

For more information on the Kearney Ag Research and Extension Center, visit: kare.ucanr.edu

California Ag Today2021-05-12T11:05:07-07:00November 27th, 2018|

Drought Tolerant Sorghum in CA

California Ideal for Drough Research

By Jessica Theisman, Associate Editor

Research is being done on drought tolerance and sorghum. California Ag Today recently spoke with Jeff Dahlberg, director of the Kearney Agricultural Research and Extension Center in Parlier about the topic.

“The sorghum research has gone pretty well for the drought tolerance; we have just finished publishing our fifth article on their first year of data,” he said.

There is a lot of interest in the research findings developing through all the drought work. California is a unique spot to do drought work on a field scale because it does not rain very often.

“That allows us to basically control the field through our ability to add water whenever we want to. I’m really excited about this,” Dahlberg said.

There are genes that are turned off and on with the application and/or lack of water.

Jeff Dahlberg, director of the Kearney Agriculture Research and Extension Center in Parlier, Fresno County

“The challenge for us now is to start taking all this data and trying to make some sense out of it,” Dahelberg explained.

It is critical to find out which genes are needed for drought tolerance and how they can get them expressed in plants.

“I think this is long-term basic research but has long-term implications in our ability to produce more drought tolerant crops to help feed the world,” Dahlberg said.

Sorghum has a long-standing history in California. It was grown here in the late 1800s. The USDA brought sorghum to California as a drought-tolerant feed.

“In the 1960s, there were almost 400,000 acres of grain sorghum grown in the state, primarily as a rotation crop for cotton,” Dahlberg said.

This crop is making a come-back with all of the droughts California has been going through.

“It’s a very drought tolerant crop. Probably one of the most drought tolerance cereal crops that we grow worldwide,” Dahlberg explained.

California Ag Today2021-05-12T11:05:07-07:00November 23rd, 2018|

Preventing the Spread of ACP

Valley Citrus Growers Continue Vigilance

By Jessica Theisman, Associate Editor

USDA ACP Cooperative Program Map (Source:
California Citrus Pest & Disease Prevention Program)

The spread of Asian Citrus Psyllid (ACP) continues to be a looming threat for Central Valley citrus growers as it vectors Huanglongbing (HLB), a disease that destroys citrus trees. Greg Douhan, a University of California Cooperative Extension Tulare County citrus farm advisor reported to California Ag Today recently that, “There have been so many people onboard really working at this from multiple angles, and we’re in the eradication mode. We want to make sure the insect doesn’t get established in the San Joaquin Valley.”

“If one were to look at a map of ACP infestation in California [such as CDFA Quarantine Maps and California Citrus Pest & Disease Prevention Program Threat map], they may consider it to be endemic in the Los Angeles area. Rest assured that anytime ACP is found in a trap, the CDFA sprays everything in that area within 400 meters.”

Douhan said the Valley is on high alert to find ACP in traps. “

If researchers discover a cluster of finds in any particular area, we manage some spray programs and try to get all the growers to do a coordinated effort in order to try to combat it,” he said.

In addition, the SAVE OUR CITRUS app is a free USDA iPhone app to report and identify the four leading citrus diseases: citrus greening, citrus canker, citrus black spot and sweet orange scab. Report your symptoms, upload a photo, and citrus experts will respond.

So far, the practices have been working well.

“I think most of the growers are very well informed,” Douhan said, “and are taking this very seriously because it is this their livelihood.”

California Ag Today2021-05-12T11:01:51-07:00November 21st, 2018|

California Sweet Potatoes are One of A Kind

California Sweet Potatoes Grow in Well-Drained Soil

By Jessica Theisman, Associate Editor

California sweet potatoes are in full harvest, and our potatoes are one of a kind, said Scott Stoddard a UCANR Cooperative Extension farm advisor for vegetable crops in Merced County. The difference is the sheen.

Scott Stoddard

“Sometimes they come up clean out of the ground because we’ve grown them in a very loose sand, so the sand just falls off of them, and it almost leaves some shine,” he said.

You can get what is called the California Sheen.

In a lot of other areas of the country, there is a little bit of mud and a little bit of silt. The crop they’re digging up is growing in the ground and kind of looks like it needs to be washed.

“A lot of times with California sweet potatoes, they don’t even look like they need to be washed when they come up out of the ground. It looks like they can just go straight from the field to fork,” Stoddard said.

Well-drained soil is important. Well-drained soil is what they grow best in.

“Not like a cactus where they can survive on no water, but we can get by in about two and a half acre feet. That’ll give you a good 100 percent potential yield,” Stoddard explained.

California Ag Today2018-10-24T16:15:13-07:00October 24th, 2018|

Livestock Owners Asked to Weigh in on Fire Impact

Livestock Owners Should Participate in Fire Survey

By Pam Kan-Rice, UC Agriculture & Natural Resources

Preparing a farm for wildfire is more complicated when it involves protecting live animals. To assess the impact of wildfire on livestock production, University of California researchers are asking livestock producers to participate in a survey.

People raising cattle, sheep, goats, poultry, swine, horses, llamas, alpacas, aquaculture species or other production-oriented animals in California who have experienced at least one wildfire on their property within the last 10 years are asked to participate in the FIRE survey.

“We will aim to quantify the impact of wildfires in different livestock production systems,” said Beatriz Martinez Lopez, director of the Center for Animal Disease Modeling and Surveillance in the UC Davis School of Veterinary Medicine. “The idea is also to create a risk map showing areas more likely to experience wildfires with high economic impact in California.

“This economic and risk assessment, to the best of our knowledge, has not been done, and we hope to identify potential actions that ranchers can take to reduce or mitigate their losses if their property is hit by wildfire.”

Martínez López, who is also an associate professor in the Department of Medicine & Epidemiology at UC Davis, is teaming up with UC Cooperative Extension livestock and natural resources advisors and wildfire specialists around the state to conduct the study.

“Right now, we have no good estimate of the real cost of wildfire to livestock producers in California,” said Rebecca Ozeran, UC Cooperative Extension livestock and natural resources advisor for Fresno and Madera counties. “Existing UCCE forage loss worksheets cannot account for the many other ways that wildfire affects livestock farms and ranches. As such, we need producers’ input to help us calculate the range of immediate and long-term costs of wildfire.”

Stephanie Larson, UC Cooperative Extension livestock and range management advisor for Sonoma and Marin counties, agreed, saying, “The more producers who participate, the more accurate and useful our results will be.”

“We hope the survey results will be used by producers across the state to prepare for wildfire,” said Matthew Shapero, UC Cooperative Extension livestock and natural resources advisor for Ventura and Santa Barbara counties, “And by federal and private agencies to better allocate funds for postfire programs available to livestock producers.”

The survey is online at http://bit.ly/FIREsurvey. It takes 15 to 30 minutes, depending on the number of properties the participant has that have been affected by wildfire.

“Survey answers are completely confidential and the results will be released only as summaries in which no individual’s answers can be identified,” said Martínez López. “This survey will provide critical information to create the foundation for future fire economic assessments and management decisions.”

California Ag Today2021-05-12T11:17:09-07:00October 18th, 2018|