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University of Delaware graduate students at the College of Agriculture and Natural Resources were featured speakers at a recent fruit and vegetable open house held at the Elbert N. & Ann V. Carvel Research and Education Center in Georgetown.
Held on August 14, 2013, the tour was co-sponsored Delaware Cooperative Extension and the Fruit and Vegetable Growers Association of Delaware (FVGAD). Research stemming from grants obtained by the University of Delaware – a five-year, $1.5 million U.S. Department of Agriculture (USDA) Specialty Crop Research Initiative grant on lima beans, and two USDA Specialty Block Grants, which seek to find alternative fruit crops for the First State – provided an opportunity for local growers to observe the research in progress, listen to updates on both the challenges and progress of fruit and vegetable crops that are grown in Delaware, and what crops, such as wine and table grapes, are being considered as a future agronomic crop in the First State.
Gordon Johnson, assistant professor of plant and soil sciences and Extension fruit and vegetable specialist serves as graduate adviser to Philip Sylvester, Kristina Smith, Harwinder Singh Sidhu, Andrew Kness and Donald Seifrit. Each participated in the tour and provided details of their current research to invited growers and industry professionals.
“Our graduate students provide the means by which more industry research can be conducted while they pursue their education,” Johnson said. Together, Extension researchers and graduate students will research critical pest and disease issues in lima beans and produce tools to help the industry further manage these issues, Johnson said. The graduate students are assisted by Heather Baker, research associate with the college.
The objective of Sylvester’s current project is to evaluate alternative control measures for root knot nematodes in lima beans. Root-knot nematodes are microscopic roundworms that can cause significant damage to the root system resulting in yield loss. Alternative controls in the project include biological control organisms, compost amendments, and the use of biofumigant mustard and sorghum species incorporated immediately ahead of planting. Microplots were established in Georgetown at the University of Delaware Research and Education Center to evaluate biological control organisms and an alternative chemical treatment. Small scale field plots were established in Salisbury at the University of Maryland Lower Eastern Shore Research and Education Center to evaluate compost amendments and the biofumigants species. Sylvester is the agriculture Extension agent in Kent County and is editor of the Kent County Agricultural Extension Blog.
Kristina Smith is a Ph.D. candidate at the University of Delaware. Smith’s studies are aimed at better understanding the spread of, and early detection of the Root-knot nematode within the lima bean fields of southern Delaware. The Root-knot nematode is a microscopic round worm capable of causing significant yield reductions within a variety of economically important crops. Smith’s research is conducted on eight different farms, at approximately 40 acres per farm. Smith’s focus is on the epidemiology of the Root-knot nematodes, how and why it presents itself in the lima bean crop.
Harwinder Singh Sidhu
Harwinder Singh Sidhu is a Ph.D. candidate whose work focuses on pod blight of lima beans caused by Phytophthora capsici. There are three primary objectives of his research. First, fields of lima beans, watermelons, cucumbers, and other host crops will be scouted for isolates of P. capsici. Secondly the surface water irrigation sources such as ponds, and streams will be baited for P. capsici. All the isolates collected from crops, and irrigation water sources will be characterized on the basis of mating types, mefenoxam (fungicide) sensitivity, and molecular markers. Third objective of the research is to study disease epidemiology. This will include various field abiotic parameters (weather and topography) that might influence pathogen outbreak and disease progress. These observations will be used to develop a model which will be tested for predicting future disease outbreaks.
Phytophthora capsici is a fungus-like pathogen of over 50 crop species worldwide, one of them being the lima bean. P. capsici was first discovered as a pathogen of lima bean in Delaware in 2000. Since then, it has spread throughout the state and the Delmarva Peninsula. The pathogen is particularly aggressive during years of heavy rainfall as soil moisture and plant wetness facilitate infection. Mefenoxam, a class of synthetic fungicides, is the only fungicide currently registered for use against P. capsici on lima bean, and has been routinely applied for protection against infection. Repeated applications of mefanoxam fungicides over the years has led to the development of resistant populations of P. capsici to this fungicide.
Kness’s research seeks to identify new classes of fungicides with efficacy towards P. capsici in an attempt to get new fungicides registered for use against P. capsici on lima beans in Delaware. This will allow farmers to rotate fungicides, significantly retarding the development of resistant populations. In addition to fungicides, he hopes to identify alternative control practices through cultural and biological control agents. The former includes testing the affect of a no-till cropping system on P. capsici disease development, and the latter includes various biological soil inoculants which have the potential to parasitize P. capsici spores in the soil and biofumigation crops such as mustard and sorghum which have soil fumigation properties. Kness was a 2012 Extension Scholar at the College of Agriculture and Natural Resources along with classmate Donald Seifrit.
Like his classmate Andy Kness, Donald Seifrit, is pursuing his master’s degree after graduating from the College of Agriculture and Natural Resources in 2012. He works closely with Johnson under the USDA Specialty Block Grants. Seifrit’s focus is on improving the fruit set and crown set in watermelons. Seifrit analyzes the pollen production of different pollenizers and collects pollen by hand, distributing the pollen, also by hand, to other watermelons in the trial. According to the Delaware Department of Agriculture, Delaware produces 100 million pounds per year, and local growers shipped $13.6 million worth of watermelon, grown on approximately 2, 800 acres. “A healthy, full sized triploid watermelon plant will normally carry 2-3 fruits at a time.” Johnson wrote in a recent issue for UD’s Weekly Crop Update. A healthy watermelon will produce more flowers than will set as fruit. Johnson writes that failure to set fruit is directly related to pollen issues caused by weather, and lack of honeybee activity. In 2013, watermelons fields lost significant pollenizer plants, resulting in reduced fruit set or fruit size. Seifrit’s research continues to look at alternative methods of pollenation.
The open house also highlighted productivity results of commercially growing crops and specialty fruits and vegetables not currently in widespread production, such as table and wine grapes, blueberries, onions, and brambles such as blackberries.
On Aug. 21, a second open house tour was held at the Bridgeville location of T.S. Smith and Sons, UD’s Specialty Block Grant partner. In their joint effort, Charlie Smith and Johnson discussed ways to extend the growing season for crops like strawberries and evaluate fruits not normally grown as a production crop in Delaware- sweet cherries, quince, pawpaws, and figs.
Over two years, Johnson will have six acres as his research canvas on Smith’s farm with UD’s portion of the grant centering on figs, cherries and strawberries. Two California strawberry varieties, Albion and San Andreas show promise in Delaware beyond the traditional April to June growing season. At this six-acre site, 2,000 pounds of strawberries were harvested by June. By mid to late summer, local strawberry production shuts down. To extend the growing season beyond June, strawberries must be protected once temperatures remain at 84 degrees or above. As growers watched, Johnson quickly placed aluminum stakes along the row and effortlessly rolled the protective covers along the strawberry beds, creating a low tunnel. Johnson will closely look at the reflective and protective properties of the white, dark grey, silver and red plastic mesh. Johnson is interested in the effect the covers will have on fruit growth and their overall value as a tool to extend the growing season. “We are looking for what we can do to complement the tourist trade,” Johnson said. “The market is there, we just need the berries.”
Throughout the growing season, UD researchers and Cooperative Extension experts schedule a variety of field tours for growers, colleagues and industry professionals at various locations. Topics such as organic farming, weed control, crop rotation, agronomic crop trials, and ornamental horticulture, provide a valuable opportunity for UD experts to engage with stakeholders in Delaware agriculture.
Click here for additional photos of the August 14 Fruit and Vegetable Open House and August 21 tour of UD’s partnership with T.S.Smith and Sons.
Photos by Michele Walfred