- Author: Mike Hsu
UC Cooperative Extension advisor tests ancient technique, new to California melons
As growers across California navigate severe drought, supply-chain challenges and rising inflation, reducing inputs has become an existential necessity. And for watermelon growers, a new twist on a thousands-year-old practice is showing real promise.
In the summer of 2018, watermelon growers brought a pressing problem to Zheng Wang, who had recently joined University of California Cooperative Extension as the vegetable crops and irrigation advisor for Stanislaus, San Joaquin and Merced counties.
Growers were seeing an increasing number of their cartons rejected by supermarkets and other buyers because of the melons' inconsistent quality, and Wang wondered if the ancient technique of grafting would help the state's melon growers, who plant about 10,000 acres of the crop each year.
Although California is the No. 3 watermelon-producing state in the U.S. (behind Florida and Georgia), there has been relatively little research on the melon across the state.
“Watermelons seem to have attracted not too much attention compared to other cucurbits, both Extension- and research-wise,” said Wang.
Fresh from his postdoctoral work at The Ohio State University on grafting fresh market tomatoes, Wang knew that vegetable growers understood the theoretical benefits of grafting, which combines a scion (the above-ground part of a plant) with the sturdy rootstock of a related plant.
But watermelon growers needed to make sure the added expense of using grafted plants would pay off. They were looking for science-backed evidence that the technique could actually reduce costs overall, while maintaining or boosting productivity.
“Sometimes as farmers we want to test a new cultural practice or crop product,” said David Jarrett, field manager at Van Groningen & Sons, who grows watermelons in the San Joaquin Valley. “A person like Zheng can set up a meaningful experiment and he has the tools for qualitative and quantitative analysis; Zheng knows how to measure a hunch and assign it a verifiable number measuring success.”
In his first trials in partnership with growers in 2019, Wang tested whether they could plant fewer watermelon plants, spaced at greater distances apart, while producing a stable yield of high-quality melons. The idea was that grafted plants, which are more vigorous and grow larger leaves and wider canopies, would produce consistently marketable melons that could be picked up to seven or eight times during an extended harvest season.
“That way we can make one plant equal ‘two,'” explained Wang, noting that non-grafted plants tend to produce only two or three picks of good melons, with quality declining rapidly afterward.
Grafting shows 'a lot of potential for the future'
After two years of trials, the growers determined, with strong confidence, that watermelons planted 4-5 feet apart could produce a yield equal to – or surpassing – that of plants 3 feet apart (the standard for their non-grafted counterparts).
According to Wang, growers reported that, on average, their successfully grafted fields produced 15% to 25% more watermelons than non-grafted fields per acre, while using 30% fewer plants and the same amount of water and fertilizers.
With the potential for greater profitability, grafting could be a major boon during a particularly challenging time for growers.
“California agriculture is stressed competing for finite resources such as land, water, fertilizer and other safe but effective chemical tools, but outside of this realm we can improve some of our crops by grafting,” Jarrett explained. “Just as many tree crops are grafted, we are learning that other crops can be successfully grafted too; the goal is to create a heartier plant, which may grow better in marginal soils with reduced inputs.”
Confidence in the technique has led to a significant increase in the planted acreage of grafted watermelon across California – from less than 250 acres in 2018 to more than 1,500 acres in 2021. At the same time, growers have adopted 4 or 5 feet as the new “standard” spacing for their watermelon plants, enabling them to reduce their populations while maintaining or boosting yield.
“Using grafting has kind of opened a new channel in the watermelon world, and for all vegetable production in California,” Wang said.
Next up for Wang is testing various combinations of scions and rootstocks. This year, he began variety trials with rootstocks of various cucurbit family members (like hybrid squashes, Citron and bottle gourd), with hopes of producing results that watermelon growers could use to decide the best options for their local conditions.
“In sum, there are a lot of unknowns – but also a lot of potential for the future,” he said.
/h3>/h3>- Author: Kathy Low, UC Master Food Preserver of Solano and Yolo Counties
Growing up, my parents told us stories of how as kids, they kept from starving during the Great Depression by not letting anything edible go to waste. To stay alive, they learned to eat beef tripe (stomach lining), chicken feet, cow tongue and other things not normally consumed. It was their stories that got me interested in learning about and sharing information on parts of fruits and vegetables normally discarded that can be preserved and eaten. Examples include citrus peel and watermelon rind.
The next time you eat an orange, grapefruit, tangerine or other citrus, you don't need to throw out the peel. Instead you can dehydrate it. Remove the pith (the white fibrous material between the skin and the peel) before placing the peel in your food dehydrator. You can also dry your peels in other methods, such as in the oven. Visit the National Center for Home Food preservation (www.nchfp.uga.edu) for more information on these alternative methods. For more information on dehydrating orange peels, see https://anrcatalog.ucanr.edu/pdf/8199.pdf.
What do you do with the dehydrated citrus peel? You can use the dried peels to add flavor to teas, or boil them to infuse the flavor in soups or rice. You can also grind the dried peels into a powder and sprinkle it on yogurt, salads, baked goods and other edibles for added flavor.
Fresh citrus peels are also often candied. The process basically involves simmering the peels in either a sugary syrup or corn syrup. You can find recipes on how to candy citrus peel at http://cecentralsierra.ucanr.edu/files/226102.pdf, https://ucanr.edu/sites/mfp_of_cs/files/312473.pdf and other sites.
If you have a sweet tooth, remember citrus peel is a key ingredient in marmalades. You're not limited to just orange marmalade. With lemon and grapefruit peel in addition to orange peel, you can make a citrus marmalade. You can find the recipe at https://nchfp.uga.edu/how/can_07/citrus_marmalade.html.
When summer comes around and you partake of a refreshing watermelon, don't throw out the rind. You can make pickles from the watermelon rind. The process to pickle the watermelon rind is similar to pickling other fruit. You'll need canning salt, sugar, distilled white vinegar, cloves, cinnamon and lemon. You can find the recipe and instructions for making watermelon rind pickles at https://nchfp.uga.edu/how/can_06/watermelon_rind.html.
But if you're like me and don't care for pickled foods, fear not, you can use the watermelon rind to make watermelon rind preserves. Besides the rind, you'll need sugar, salt, lemon juice and ground ginger. You can find the recipe for making watermelon rind preserves at https://nchfp.uga.edu/how/can_07/watermelon_rind_preserves.html.
Or, take the watermelon rinds and candy them in a similar way that you candy citrus rinds. Peel the green off, cut them into chunks and cook them in a syrup until they're translucent and then dry them. You'll be surprised at how good they are. Find the recipe at https://ucanr.edu/sites/camasterfoodpreservers/files/335009.pdf.
So the next time you eat citrus or watermelon, don't throw out the peels and rind before trying candied citrus peels and dehydrating the peels, and making pickles, candy or preserves from the watermelon rind. Remember that old saying, “Waste not, want not!”
For more information about the UC Master Food Preserver Program, including the Food Preservation Video and Recipe Libraries, visit mfp.ucanr.edu.
- Author: Kathy Keatley Garvey
The researchers, led by Rachael Winfree of Rutgers University, New Brunswick, N.J. set out to answer the question “How many species do we need for crop pollination?”
They identified more than 100 species of wild bees pollinating watermelon, cranberry and blueberry crops on a total of 48 farms in New Jersey and Pennsylvania--the mid-Atlantic region of the United States.
The answer: “Not nearly enough bees are available for crop pollination,” Winfree said.
“We found that maintaining ecosystem services in nature requires many species, including relatively rare ones,” said Winfree, professor of ecology, evolution and natural resources. The publication, “Species Turnover Promotes the Importance of Bee Diversity for Crop Pollination at Regional Scales,” appears in the section, Ecology.
The ecologists first counted pollen grains of different bee species to measure bee pollination, tallied the number of bees and the different species pollinating the crops, and then figured out the minimum set of bee species that could meet various pollination needs. Finally, they plotted the cumulative number of bee species needed against the number of sites.
“So how many species do we need to ensure reliable crop pollination?” he asked. “The answer to this question helps us manage our agricultural and natural lands. Past studies suggest that often just a few bee species can do the job for any one site.”
The study, among the first of its kind, “reveals that when we look across multiple farm sites in a region, we need many more species than experimental studies have suggested in the past,” Williams said. “At one farm, pollination might rely on a handful of species, but across 40-50 farms in a region we need 10 times that number. This is because the most important species change from one place to another. “
So how many bee species are important to ensure crop pollination?
“More than we thought!” Williams said. “Working to promote bee diversity across regions is important for maintaining pollination and secure food systems.” The researchers counted 100 species of wild bees.
Winfree said previous experiments completed in the lab didn't answer the question: “How many bees do we really need?”
“When you have five (ish) bee species you get enough pollination,” she said “But there are only so many species you can even fit in an experiment. What we wanted to know is, how many bees do real farmers need to pollinate actual farms across an entire state?”
“Any one farm might need only a few species, but different bee species pollinate the different farms, so to pollinate all 50 (ish) farms we needed about 10 times as many species as are needed in smaller scale experiments,” Winfree said. “More than half of the 100 (ish) bee species we saw in the study were needed at some farm for some crop.”
Winfree, reiterating that “we need more bees than we thought,” said the issue is “important because many scientists are concerned that bees are in trouble. There is limited information on how most bee species are doing, but some of the species we do know about are declining. This work shows that preserving lots of bee species is important for food security.”
Other co-authors of the study are James Reilly of Rutgers; Ignasi Bartomeus of Rutgers but based at a biological station in Seville, Spain; Daniel Cariveau of Rutgers and the University of Minnesota; and Jason Gibbs of the University of Manitoba, Winnipeg, Canada.
A grant from the National Institute of Food and Agriculture (NIFA) of the U.S. Department of Agriculture funded the data collection research. Winfree conceived the study, oversaw the data collection, led the conceptual development and wrote the manuscript. Williams contributed to the conceptual development and manuscript preparation.
![A brown-belted bumble bee, Bombus griseocollis, pollinating a blueberry flower. (Photo courtesy of Rachael Winfree) A brown-belted bumble bee, Bombus griseocollis, pollinating a blueberry flower. (Photo courtesy of Rachael Winfree)](/blogs/blogcore/blogfiles/50443.jpg)
- Author: Kathy Keatley Garvey
Then think of watermelons and pumpkins.
All those crops will be discussed in a series of free webinars on Ensuring Crop Pollination in U.S. Specialty Crops, set Jan. 24 through March 28.
The webinars will feature five researchers with the Integrated Crop Pollination Project (ICP), including ICP co-principal investigator and pollination ecologist Neal Williams of the UC Davis Department of Entomology and Nematology. They are free and open to the public. Each will be 45 minutes to 60 minutes long.
Coordinating the series are Katharina Ullmann, national crop pollination specialist with the Xerces Society for Invertebrate Conservation, and Extension apiculturist and professor John Skinner of the University of Tennessee. Closely linked to UC Davis, Ullmann received her doctorate in entomology from UC Davis, studying with Williams.
"The majority of U.S. specialty crop growers depend on bees for pollination of their crops," Ullmann said. "Growers know that without adequate pollination, they would not be profitable. But what are the best pollination strategies for fruit, vegetable, and nut crops? What farm management practices can growers use to support bees and the crop pollination they provide?"
First to present will be Theresa Pitts-Singer, who collaborates with Williams. She will discuss Ensuring Almond Pollination on Jan. 24 and also deliver the ending seminar on March 28 on How to Manage Solitary Orchard Bees for Crop Pollination.
Williams will speak Feb. 28 on On-Farm Pollinator Benefits for Watermelon Pollination. An associate professor of pollination and biology and a Chancellor's Fellow, Williams serves as the faculty co-director of the UC Davis Honey and Pollination Center and is a member of UC Davis Agricultural Sustainability Institute. His applied research addresses the integration of wild and managed bees for pollination of diverse agricultural crops including seed production, row crops and orchards.
His research addresses a series of questions:
- Under what contexts, in terms of local management and landscape context, can native pollinators provide sufficient pollination for different crops?
- How can we enhance habitat and diversify agricultural systems to promote managed and wild bees?
- Do pollinators like honey bees and wild bees interact in ways to increase the overall effectiveness of crop pollination?
The answers to these questions will help alleviate the stress placed on honey bees, Williams says, and also "inform ways to more sustainability manage agricultural systems to promote biodiversity and production."
Williams has worked extensively in agro-ecosystems in California's Central Valley and in eastern Pennsylvania and New Jersey. His work in the East and West has helped form the basis for pollinator conservation planting guidelines. A continuing goal, he says, is to provide practical information that can be used to improve the long-term stability of pollination for agriculture in California, as well as promote pollinator conservation and management.
All speakers will discuss their research, and engage with the audience in discussing pollination of wild bees, honey bees and other managed bees in almond, blueberry, tree fruit, pumpkin, and watermelon. Each registered attendee will later receive a link to the slides.
To register, attendees can click on each link (note that all times here are 11 a.m., Pacific Time (consult your time zone):
- Jan. 24: Ensuring Almond Pollination (Theresa Pitts-Singer, USDA-ARS and Utah State University)
- Jan. 31: Pollinating Highbush Blueberries: Bees Bring Bigger Berries (Rufus Isaacs, Michigan State University)
- Feb. 14: Pollinating Apples and Cherries East of the Rockies (Julianna Wilson, Michigan State University)
- Feb. 28: On-Farm Pollinator Benefits for Watermelon Pollination (Neal Williams, University of California, Davis)
- March 21: Ensuring Pumpkin Pollination (Shelby Fleischer, Pennsylvania State University)
- March 28: How to Manage Solitary Orchard Bees for Crop Pollination (Theresa Pitts-Singer, USDA-ARS and Utah State University)
The webinar series will be hosted by eXtension.org, an online Cooperative Extension network. Funding will be provided by the Integrated Crop Pollination Project, a USDA-NIFA Specialty Crop Research Initiative Grant (#2012-51181-20105). Plans are to offer continuing education credits for certified crop advisors.
Want more information about the series? Access the Bee Health eXtension.org website or email icpbees@msu.edu.
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- Author: Janet Byron
A new federal voucher that gives low-income women access to a range of fruits and vegetables could provide unique new marketing opportunities for California growers.
In 2009, the federal Special Supplemental Nutrition Program for Women, Infants and Children (WIC) began distributing monthly cash vouchers to low-income women with children to buy fruits and vegetables. The program reaches almost half of the infants and one-quarter of children under 5 years old in the United States.
A team of UC Cooperative Extension (UCCE) researchers and nutrition advisors has been exploring the possibility of developing a farm-to-WIC program that would link these low-income consumers with local growers. The purpose of such a program would be to increase the consumption of a wide variety of fresh produce, with a focus on locally grown produce when available.
UCCE conducted a survey of produce preferences and buying habits among WIC participants in Tulare, Alameda and Riverside counties in 2010. The full study is published in the January-March 2012 issue of California Agriculture journal.
Based on the results, the UCCE team developed a list of 19 produce items to promote in a possible new farm-to-WIC program. They are:
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Although mustard greens and collards were not popular across all sites, the advisors gauged a potential market in Alameda County, so these were retained. Based on write-in responses, oranges were also added.
In California, which has the nation's largest WIC program, 82 local agencies serve about 1.43 million participants at 623 local centers, and WIC participants can redeem their monthly vouchers at 4,000 grocery stores statewide. About 40 percent shop at WIC-only stores, which stock and sell only WIC-authorized foods.
Stocking produce is relatively new to WIC-only stores; before rollout of new WIC food packages in October 2009, these stores were only required to stock limited amounts of fresh carrots. In the survey, most WIC participants (58 percent to 72.3 percent) responded that their preferred stores offered many choices, but fewer participants (18.5 percent to 41 percent) rated the produce quality as “excellent.” Key factors determining purchase decisions were produce quality and freshness, and nutrient value (vitamins and minerals). Cost was relatively less important, possibly because WIC participants procure the produce with the vouchers.
The list has served as a starting point for discussions with growers and WIC vendors.
“The survey showed that WIC participants were interested in purchasing fresh produce with better quality and more variety,” wrote lead author Lucia L. Kaiser, Cooperative Extension specialist in the UC Davis Department of Nutrition, and co-authors, in California Agriculture. “Some WIC participants that we surveyed said they avoided shopping at WIC-only stores in part because these interests were not met.”
![A dish made with nopales (cactus pads). A dish made with nopales (cactus pads).](/blogs/blogcore/blogfiles/10200.jpg)