O Christmas Tree

December 5, 2013 under Cooperative Extension

Phytophthora root rot is problematic on tree farmsIn December, many people are shopping for a perfect cut tree or live tree to decorate their homes. There have been recent reports in 2013 regarding root rot in fir, causing problems for Christmas tree growers.

Phytophthora root rot is problematic on tree farms in Oregon, North Carolina and many other states where Christmas trees are grown. Phytophthora is a fungus-like organism sometimes called a water mold, of which many species cause plant diseases including root rots on numerous host plants. Phytophthora root rot is favored by wet, saturated soils. The mid-Atlantic region had an abundance of rain in the spring of 2013, which led to saturated soils on many farms, especially those with poor drainage. Roots in saturated soil may be stressed and may be more susceptible to root invading microorganisms.

This time of year, though, when everyone is looking for a sale or a bargain, it is good to remember that our local Christmas tree growers deal with many challenges to growing a perfect tree, an expensive and time consuming process.

A Christmas tree takes 8 to 10 years to grow to a good size, and there are many hurdles along the way. Trees must be planted properly in good soil, not too shallow or not too deep. It may take up to three years for a transplanted seedling to establish a good root system. Young trees in particular may be killed in a few weeks by Phytophthora infections in the roots. Fraser, noble, concolor, and canaan fir are all susceptible, as is Douglas fir although it is not a true fir species (Abies). Nordmann fir may be less susceptible. Other root rotting fungi and microorganisms can attack roots of fir and pine. The best management strategies for root rot are the purchase of clean healthy seedlings and proper site selection, because the best possible control is avoidance of Phytophthora root rot in the first place.

If trees become established and growers avoid root rot, there are many other pests and diseases that attack Christmas tree species. There are needlecast fungi that cause spotting and discoloration of needles, and needle drop. Growers must scout their trees, apply fertilizer and pest control, trim to shape, and keep up with research on tree species and new varieties. Sales of trees, following the 10 year nurturing, all occur yearly within a 4 to 6 week period. Our Christmas tree growers are dedicated agricultural professionals who love to see smiles on the faces of people who purchase and enjoy the trees that they grow!

Article by Nancy Gregory


UD awarded $1.5 million USDA grant to study lima beans

January 11, 2013 under CANR News, Cooperative Extension

Researchers from UD study lima beansDelaware is currently the number two producer of lima beans in the United States, second only to California and with the possibility of becoming number one in the future.

Because of this, it is imperative to study the many aspects of various diseases affecting the crop in Delaware and throughout the mid-Atlantic region.

Such work requires a collaborative effort and a team has been assembled thanks to a five-year, $1.5 million U.S. Department of Agriculture (USDA) Specialty Crop Research Initiative grant.

The grant awarded to the University of Delaware includes researchers from UD, Delaware State University, the University of Maryland, Ohio State University, Cornell University and the University of California Davis (UC Davis) who will begin studying the various effects of plant disease on lima beans in the First State.

The many aspects of this grant will include studies that are being conducted for the first time in history.

There are six components to the grant, each with various researchers studying different parts of the problem. They are conducting research on downy mildew, pod blight, white mold, root knot nematodes and germplasm resources and developing an economic analysis.

Downy mildew

Downy mildew is a fungal-like disease of the lima bean caused by Phytophthora phaseoliand the goal of the research team is to improve disease forecasting and look at genetic diversity of the population of the pathogen. In this way, researchers will be able to inform farmers of their risk of occurrence of the disease and have a better understanding of the genetics of the pathogen.

Tom Evans and Nicole Donofrio, professors of plant pathology in the Department of Plant and Soil Sciences in UD’s College of Agriculture and Natural Resources, and Nancy Gregory, plant diagnostician for UD, will work together on this part of the project.

Pod blight

Pod blight is caused by the pathogen known as P. capsici and Gordon Johnson, assistant professor of plant and soil sciences at UD, will work on this part of the study with Evans and Gregory.

Unlike downy mildew, which is a disease that generally affects only lima beans, P. capsicihas a very wide host range. Once it strikes a particular crop, it is very difficult to get rid of, with pathogen’s spores lasting up to 10 years in the soil. Because of this, pod blight is an increasing problem for growers. The disease occurs in low-lying areas of fields and is more frequent in wet years. Therefore, this part of the project has three goals: to look for a fungicide to deal with the disease, to monitor the disease, and to look for alternative or organic non-pesticide driven strategies for control.

The study is also looking at risk management strategies, including information for growers in the state about the best time to spray for disease control and consideration of alternate control strategies.

Gregory, who diagnoses field samples collected by the research team and growers, maintains cultures of the pathogens and produces  the inoculum for the studies, said that the researchers are eager to “learn more about the epidemiology and the spread of pod blight and downy mildew, that will enable us to do a little bit better job on forecasting.”

She also noted how great is to have so many expert researchers involved, noting that she is looking forward to making significant progress on problems that have plagued the region for years. “To pull together a strong team of researchers like this and many new graduate students is really going to pull a lot of this research together and we’ll really come up with some great results.”

White mold

Kate Everts, an adjunct associate professor of plant and soil sciences at UD and a Cooperative Extension specialist with both UD and the University of Maryland, is leading research on alternative ways to control white mold, another disease that is very difficult to eliminate.

With an even broader host range than P. capsici, and an even longer life — persisting in soils for 20-30 years — finding out as much about the disease as possible, as well as possible ways to control it, is imperative.

Everts will look not just at lima beans but other crops, as well, as she tests biological control strategies and alternative control strategies for dealing with the white mold.

Click here to read more.. »


Nematode Assay Service

August 15, 2012 under CANR News, Cooperative Extension

The University of Delaware Nematode Assay Service processes samples on Tuesdays of each week. This fee based service provides identification and enumeration of plant parasitic nematodes in soil and plant tissue.  The next set-up date will be August 21, 2012. Please note fee changes, and utilize the new form available as a pdf on the website, available by clicking here. A completed form must accompany submitted soil samples. Troubleshooting plant and root samples may be submitted at any time.  For more information visit the UD Plant Diagnostic Clinic website or call 302-831-1390. The Clinic is located in 151 Townsend Hall, 531 South College Avenue, Newark, Delaware.  A parking space for sample drop offs is located behind Townsend Hall.

For a useful video on how to sample for nematodes, visit the University of Delaware College of Agriculture and Natural Resources YouTube page. Or, see this video for diagnosing nematode damage in the field.


Thousand Cankers Disease of Walnut Close to DE

August 14, 2012 under Cooperative Extension

TCD on black walnut – image courtesy of Karen Snover-Clift, Cornell University

Thousand Cankers Disease (TCD) of black walnut was found in central Virginia along I-95 in 2011, and later that year in Bucks County, PA. TCD is a disease of walnut trees, Juglans spp., and it has continued to spread east in the last few years, after initial finds in the Western U.S. and Tennessee. The causal fungus is carried by the very tiny walnut twig beetle. Small cankers form under the bark of the tree, and ultimately trees die. Yellowing and dieback in the tops of trees are usually the first symptoms. Native black walnuts in Delaware are at risk.

Contact the UD Plant Diagnostic Clinic for information.151 Townsend Hall, 531 South College Avenue, Newark, DE. (302) 831-1390.

Click here for a fact sheet about the disease.



UD Garden for Community intern helps others while growing job skills

July 30, 2012 under CANR News, Cooperative Extension

Owen Cass wants to be a farmer when he gets out of college. While most people would assume that’s not an unusual aspiration for a student in the University of Delaware’s College of Agriculture and Natural Resources, it actually is. Careers in research, agri-business, natural resources management and veterinary science are more typical choices.

What’s even more out of the ordinary is that Cass comes from a suburban background. He doesn’t recall his parents growing so much as a tomato plant when he was a child in Bryn Athyn, Pa.

But this 22-year-old is getting plenty of experience growing tomatoes – and squash, sweet corn, cukes, peppers and much more – in UD’s Garden for the Community.

Cass is a summer intern for this one-third acre garden that produced three tons of vegetables and herbs last year, all of which were donated to the Food Bank of Delaware.

The garden, located on UD’s Newark Farm, is managed by Mike Popovich, a Cooperative Extension associate.

Now in its fourth year, the garden does good things for low-resource Delawareans who may not have the opportunity to eat many fresh vegetables. “We’re so excited to get fresh-picked produce out to our hunger relief partners in the community,” says Kim Kostes, communications director of the Food Bank. “As soon as Owen or Mike arrive with the day’s harvest, we get it right back out the door.”

The garden also does good things for students like Cass, who was eager to show off this season’s crops on a recent 95 degree day. Despite the heat, Cass vigorously strode between the garden rows, pointing out pumpkins he had planted the week before; hibiscus-like blooms on okra plants; Japanese beetle damage on basil; and the “Florida weave” style of staking used on heirloom tomato plants.

(In the Florida weave technique, you drive a stake between every two or three plants and attach a string at the end of each row. You then weave the string between the plants.)

“Even during a bad thunderstorm the other night, the tomatoes stayed upright,” says Cass. “Our peppers fell over but some international students volunteered the next day and helped to get them re-staked.”

Farming requires knowledge not just about combating pests and re-staking plants but also about managing people. Cass hopes to own his own farm, in which case he may have dozens of employees under his direction. This summer, working with 200-plus garden volunteers, he is getting plenty of supervisory experience. A half dozen or so core volunteers show up every Saturday; others, like the international students, help out just once.

“I can’t believe the amount that I’m learning,” says Cass. “Mike lets me make a lot of decisions on my own, whether it’s managing the volunteers or choosing which kind of seeds to plant for our second season of crops.”

“I also get to learn from Extension and college experts,” he adds. “Nancy Gregory [an Extension plant diagnostician] was out in the garden recently because she needed downy mildew samples for a research project. She didn’t have enough in her own test plots but, unfortunately, we had it on our cucumbers.”

Despite a bit of downy mildew and Japanese beetles the Garden for the Community always enjoys high yields. Popovich is the first to admit he has plenty of advantages over the home gardener. “The UD community gets very excited about this garden,” says Popovich. “I’m fortunate to have a steady stream of Cooperative Extension professionals and UD agriculture researchers popping by to give advice and lend a hand.”

“And Owen has been tremendously helpful with planting, weeding, harvesting and other chores,” Popovich says. “He has taken an immense amount of initiative early on.”

“Not one nuisance insect or weedy plant goes unnoticed by him,” he adds. “Owen checks with college professionals — and his smart phone — to identify bug and disease issues. On one occasion, I saw him spend 20 minutes trying to catch a single squash vine borer. That’s the type of dedication I like to see in an intern.”

Cass will be extra busy in the weeks ahead, getting the garden in picture-perfect condition for the Aug. 9 Evening in the Garden, a benefit for the Food Bank of Delaware. Held under a tent, adjacent to the Garden for the Community, the event features fresh-from-the-garden food, fine wine, live entertainment and garden tours.

The meal will be prepared by students from the Food Bank’s Culinary School.  “At the beginning of the season, Mike connects with us and makes sure to plant the crops that the students will need for their recipes,” says Kostes. “This year’s menu includes tri-colored bruschetta, roasted vegetables, salmon with tomatillo sauce, and potato and goat cheese salad.”

Tickets for Evening in the Garden cost $40, or $15 per student with ID. After Aug. 2, ticket prices increase to $50, and $25 per student. Call Kostes at 444-8074 or email her at kkostes@fbd.org.

Article by Margo McDonough

Photo by Danielle Quigley

This article can also be viewed on UDaily.


UD assists Dogfish Head in developing yeast for Delaware Native Ale

November 8, 2011 under CANR News, Cooperative Extension

Delaware is the first state to have its own yeast. Gov. Jack Markell signed a proclamation giving a yeast named Kloeckera (apiculata) (strain KA 1) this designation, which is an honorary title because the state legislature is not currently in session to vote on the matter.

The yeast is the key ingredient in Delaware Native Ale, or DNA, a new, limited-time ale created by Dogfish Head Brewery that features grown-in-Delaware hops, peach and pear juices and other native ingredients. The light ale was introduced recently at a mid-day gathering at the brewery’s pub in Rehoboth Beach.

Tom Evans and Nancy Gregory had every right to feel like proud parents at the event – after all, they isolated the yeast, identified it, and gave it its first home, in laboratories in the University of Delaware’s College of Agriculture and Natural Resources.

Evans is a professor of plant pathology in the Department of Plant and Soil Sciences. Gregory is a Cooperative Extension associate in that department who works closely with Evans on other research projects. She spends most of her days in UD’s Plant Diagnostic Clinic, looking for bad guys — fungal, bacterial and viral diseases that have shown up on a farmer’s crops or a homeowner’s prized garden plant. After she has identified the pathogen, she and other Extension colleagues usually are able to present solutions for controlling the problem.

But for the Dogfish Head project, Gregory was looking for good guys – yeasts that would make the perfect base for a native Delaware brew. Yeast is the single most important ingredient in beer brewing. As a fungus, it’s a living organism that metabolizes, reproduces and lives off ingredients in beer. During the beer’s fermentation stage, yeast is responsible for converting sugar to alcohol and carbon dioxide. It also plays a large part in what the beer will ultimately taste like.

There are literally thousands of varieties of yeast in the world, notes Gregory, including wild yeasts. Dogfish already possesses a proprietary, cultivated yeast that it uses for the majority of its beverages, according to Katrinka Housley, a lab technician with Dogfish.

But the brewery wanted a wild yeast, native to Delaware, for the new ale. State Secretary of Agriculture Ed Kee steered Dogfish’s brew team to Evans and Gregory for guidance in finding just-the-right yeast.

One day in early August, a team from Dogfish that included Housley, her supervisor, Steven Thompson, and brewery president Sam Calagione, met up with Gregory and Evans at Fifer Orchards, which offered to be the yeast source. Bobby Fifer, a co-owner of the orchards, showed the group around, scoping out good sites. They eventually settled on a few locations to trap yeast, including the packing house, underneath peach trees in the orchard, and near a bunch of hovering fruit flies.

“Fruit flies can be a great source of yeasts,” says Gregory. “They travel to so many different fruits and vegetables and get lots of things stuck on their legs.”

(No worries, Dogfish fans. Fruit fly yeast did not end up in the new ale.)

The group set out about 100 agar plates — petri dishes containing a growth medium to culture microorganisms. They snacked on Fifer doughnuts for about a half hour while the plates trapped yeasts.

Gregory and Evans then grew and isolated numerous wild yeasts over a period of several weeks in “dirty” and “clean” labs at UD. (As the name implies, the clean lab is kept free of contaminants, while things like a leaf with bacteria or a pumpkin with fungi are allowed inside the dirty lab.)

“At that point in the development of a yeast isolate, you’re weeding through all the chaff to get to the wheat,” notes Evans. “You’re looking at microscopic budding cells under a microscope, separating yeasts from other fungi and bacteria, or other material.”

The UD scientists incorporated their noses into the culling process, too. “Some yeasts smell like bread, some a little fruity and some just plain foul,” says Evans. The stinkers were immediately taken out of the running.

A dozen or so promising candidates for the ale were sent to Dogfish in mid-August. Before they were shipped, Gregory identified each isolated, pure yeast strain through several tests, collaborating with colleagues in CANR and at Delaware Biotechnology Institute.

Once Housley and Thompson had the strains of yeasts on hand they had just a few weeks to see which ones performed best in sample brews that were then tasted by Dogfish’s 37 trained tasters.

“It was challenging working with wild yeast strains,” says Housley. “They are a little more unpredictable than cultivated strains.”

The winning yeast, Kloeckera (apiculata) (strain KA 1) originated in a box of peaches that were “seconds” — not quite picture perfect and up to Fifer standards.

“As a land-grant institution, UD is committed to working with Delaware’s agricultural producers to improve their profitability,” says Evans. “We’re involved in education, applied research, and outreach to agricultural operations throughout the state. This project was a new one for us, but it certainly fits with our mission.”

And Dogfish was very happy to get the help.

“Tom and Nancy’s brain power and wealth of knowledge were invaluable,” says Thompson.

Evans plans to incorporate information about finding Kloeckera (apiculata) (strain KA 1) into a class he teaches each fall. The students will even get to see a sample of Delaware’s new state yeast, which Gregory has safely stored away in a liquid nitrogen cabinet in the clean lab.

Article by Margo McDonough

Photos by Danielle Quigley and Nancy Gregory


CANR researchers team up to combat lima bean disease

February 3, 2011 under CANR News, Cooperative Extension

When battling downy mildew, a potentially devastating disease that strikes lima beans (Phaseolus lunatus), one of Delaware’s most important vegetable crops, assembling a team of experts to attack the problem from all angles is a must. That’s why a diverse group of plant scientists in the University of Delaware’s College of Agriculture and Natural Resources has joined together to battle this important plant disease.

Tom Evans, professor of plant pathology in the Department of Plant and Soil Sciences, and many graduate students have studied downy mildew over the past 15 years.

Evans said lima beans are vital to agriculture in Delaware and are “the cornerstone of the state’s processing vegetable industry.” Approximately 6,000 hectares of baby lima beans are grown annually, with a farm value of over $6 million. If lima bean cannot be grown profitably in the state, then many other processing vegetables would not be grown due to the economics of processing.

Downy mildew, caused by the fungus-like organism Phytophthora phaseoli, is prevalent in Delaware because it thrives in humid conditions, and lima beans are grown on small, dense acreage. Evans said that most lima bean growers are concentrated in close proximity from Dover to Georgetown and from the Delaware Bay west into Maryland, so wind-driven rain makes it easier for the pathogen’s sporangia to move from one lima bean field to another.

That was the case in 2000, when downy mildew caused $3 million damage in what Evans called “the largest downy mildew of lima bean epidemic ever recorded.” Two factors contributing to this epidemic were the emergence of a new race of the pathogen, Race F, which overcame the genetic resistance of lima cultivars being grown, and frequent wind-driven rain that spread the pathogen’s sporangia.

With the emergence of Race F, growers could no longer rely on downy mildew resistant lima bean cultivars to prevent the disease, as they had in the past. New cultivars with resistance to Race F need to be developed and in the meantime growers have relied upon fungicides to manage the disease.

Bob Mulrooney, extension specialist in plant pathology, has tested fungicides for effectiveness against downy mildew for a number of years and has identified new more environmentally-friendly chemicals which offer good control. Mulrooney’s research results are the basis for growers’ current downy mildew management practices.

Evans and his group have been responsible for studying the biology of the pathogen, monitoring the evolution of new races of the pathogen and the epidemiology of the disease.

Extension associate Nancy Gregory diagnoses the disease on samples sent in by growers, maintains the pathogen in culture for field and greenhouse experiments, and determines their races.

Emmalea Ernest, an extension associate at the Carvel Research and Education Center in Georgetown, Del., breeds lima bean for desirable traits, such as disease and drought resistance, and is developing cultivars for Delaware farmers. Ernest and Evans work together screening lima bean germplasm from around the world for resistance to races E and F of P. phaseoli. Ernest has conducted experiments to determine how the resistance genes are inherited. After making crosses between resistant parents followed by several years of field screening, Evans and Ernest are testing lima bean lines with resistance to both races this summer.

Nicole Donofrio, assistant professor of plant and soil sciences, is responsible for the pathogen side of the study, trying to understand the pathogen’s virulence mechanisms, and how it evolves to attack certain aspects of the plant. Donofrio said, “In order to fight the disease, you have to know your enemy, and the more you know your enemy, the more equipped you are to tackle it when things like a new race emerge.”

Knowing exactly how to fight against the disease from a pathogen standpoint is difficult. Donofrio points out that P. phaseoli has over 500 effector genes, molecules that bind to a protein altering its activity and enabling infection. To study effectors, Donofrio and doctoral student Sridhara Kunjeti took a two-pronged approach. First, they took what they knew about P. infestans, the pathogen responsible for the Irish potato famine and a close relative of P. phaseoli, and searched for similar genes in P. phaseoli to determine if it used similar mechanisms in its attack on lima bean.

Next, they looked at lima beans that had been infected for three and six days to see which effectors were active during those time-points of infection. Donofrio said this could lead to a breakthrough because if they are able to characterize the effector genes, they can look for traits that could be a countermeasure to pathogen attack and thereby block pathogenesis.

Randy Wisser, assistant professor of plant and soil sciences, works on aspects of quantitative genetics and plant breeding and Blake Meyers, Edward F. and Elizabeth Goodman Rosenberg Professor and chair of the Department of Plant and Soil Sciences, works on genomics of lima bean-downy mildew interactions.

In various combinations, the research team has received over $200,000 from various CANR seed grants and Delaware state grants to more fully explore P. phaseoli and downy mildew.

Article by Adam Thomas

This article can also be viewed online on UDaily by clicking here.