Written by: Owen Washam, Research Assistant in the Plant Pathology Department at University of Wisconsin-Madison
Another field season is behind us! And with these learnings, in this update, I will share some of the common issues and potential solutions organic process celery growers face. After a cold wet start to the year, we had a beautiful summer in south central Wisconsin. Regular rains and mild weather were conducive for growing organic celery, from transplanting in May to final harvest in late August. This year, we also observed lower pest and disease pressure relative to 2021.
We grow organic celery entirely for organic meat processors; the crop is grown for juicing and nitrate extraction as a process vegetable, meaning its management differs from table celery grown for fresh markets (consumers). In our Wisconsin research trials, we have found that cultivar selection, nutrient amendments, and plant health each affect crop quality and nitrate yield.
Variety Selection
Considering the end goal of organic celery that yields high levels of nitrate upon extraction, a cultivar with significant nitrate accumulation and other important traits must be chosen.
Cultivar trials conducted by former staff member, Dylan Bruce, in 2016 and 2017, found that ‘Tall Utah’ and ‘Mission’ had the best nitrate accumulation compared to others tested. Low performing cultivars include ‘Safir’ and ‘Tango’. ‘Tango’ was also notably susceptible to pests and diseases, relative to other trialed cultivars. In our 2021 and 2022 field trials, we exclusively grew ‘Tall Utah’ based on these preliminary studies.
Nutrient Amendments
Nutrient management in organic systems requires a system-based approach with judicious fertilizer application. One research goal is understanding the appropriate nitrogen (N) rate for optimizing nitrate yield in organic celery. We hypothesized that greater N application will result in greater nitrate accumulation within the plant tissue. Soil tests determined our field site had phosphorus and potash in excess, so we chose 13-0-0 feathermeal as our N source. It was applied at a range of rates from 0 to 300 lbs N/acre.
We also used an oat/pea cover crop, or “green manure,” on half the plots to study: a) any effects and b) any interaction with the feathermeal on nitrate accumulation. Preliminary analysis indicates our hypothesis was correct to a point. Nitrate yield significantly differed between N rates, and nitrate yield increased with increasing feathermeal (N) application rate – however, the yield levels off at the highest N rates. In both years, we found no cover crop/feathermeal interaction or effect on nitrate yield. This may be explained by low cover crop biomass, limited by drought in spring 2021 and cold-delayed planting in spring 2022.
Plant Health
Disease management in organic systems require a proactive system-based approach. Promoting soil health by cover cropping and rotating a diverse set of crops can be helpful tools for mitigating disease, positively effecting plant health. In southern Wisconsin, we observe the first disease cases on celery in late July, as inoculum moves in on weather fronts and through insect vectors.
From that point, we monitor plant health and insect pest populations weekly until the final harvest. One of the biggest issues we saw in both years was blackheart of celery, which causes inner petiole blackening (see images) and dieback.
Blackheart is a physiological issue caused by calcium deficiency related to persistently dry soils or improper irrigation. Other major issues we observed were crown rot and soft rot, caused by pathogenic fungi and bacteria respectively.
All mentioned celery crown issues eventually kill affected plants, and causal pathogens can spread to neighboring plants by contact or rain splash. Rot related issues caused significant losses in our 2021 trial, likely attributed to early season drought and inoculum-spreading heavy rains near harvest. In 2022, these issues were limited. In both years, insect vectored diseases were observed in low incidence. These include aster yellows disease vectored by leafhoppers and various mosaic viruses by aphids.
With fall upon us and the season at its end, the next steps will be an analysis of the data collected over the field season and a write up of our findings
Left picture: plant with crown rot
Right picture: healthy plant
Written by: Siyuan "Steven" Sheng, research assistant in the Meat Science and Animal Biologics Department of University of Wisconsin-Madison
For the last six months, we’ve tested different vegetable powders in the curing of organic meats at the new Meat Science and Muscle Biologics building at the University of Wisconsin-Madison.
To learn more about how vegetable powders are involved in the curing of organic meats and meat curing in general, you can learn more here on our project page. Curing is a form of food preservation that prevents the spoiling of meat from bacteria and adds flavor through the addition of salts, sugars, or nitrites to draw out moisture, allowing the meat to last longer, anywhere from weeks to months, depending how the meat is packaged and stored.
Dehydrated celery or celery powder contains nitrite (NO2), a form of salt that is often used to cure meat. Most of the commercial curing powders used in organic meats are not organic.
Current regulations for organic processed meats allow the use of nonorganic vegetable powders, like celery powder, for curing meat, but these allowances are expiring and changes are coming to the USDA National Organic Program regulations to restrict this. Given this history, this is why this research is important: testing and expanding the procurement of organic celery and vegetable powders, so that the organic meat industry can comply with the USDA organic regulations for the curing and processing of meat.
To test the vegetable curing agents, we grind turkey breast to form deli meat and beef for frankfurters, adding in the organic celery and Swiss chard powders from the vegetables we have grown, as well as organic fruit powders to act as a catalyst for the curing process, and then compare the effectiveness of our curing agents to those that are commercially available.
As the meat ferments or cures in the cookhouse, the fermentation process converts the nitrites in the vegetable powders to nitrates. This process changes the color of the meat over time and after a couple of weeks in cold storage once the color is developed, we evaluate the meat.
Using members in our department as panelists for now, we perform sensory evaluations or “taste tests” of the cured meats after 14 days, and also look at the levels of residual nitrite and color stability in the turkey deli slices and beef frankfurters after up to 90 days to assess the shelf life of the cured meats from our experiments. To measure the color stability of cured processed meat, we take colormetric measurements using a “Hunter meter” and refractometer and to measure levels of residual nitrites, we use high-performance liquid chromatography.
Next steps moving forward will be to evaluate vegetable cure agents, like celery powder, on other types of meat and using other cooking methods with a larger panelist pool that is more representative of consumers for a more formal sensory evaluation.
Different treatments of celery and fruit powder cure agents on turkey deli meat
We planted our summer crop of organic celery in early June. The transplants had a rough start, as trace precipitation fell between planting and mid-June. The ongoing drought in south-central Wisconsin has meant heavy reliance on our irrigation system. Thanks to the drought and the hardworking field crew, weeds have not posed issues. To date we have observed moderate pest pressure from chewing beetles and lepidopteran immatures, and minimal-no disease pressure. We are beginning to see an anticipated increase in leaf hopper and leaf miner populations. We have also seen a few cases of blackheart throughout the field, likely due to drought conditions and inconsistent water availability. Our first harvest in early July was successful, and we are analyzing the celery juice nitrate levels using two different protocols in collaboration with the UW Meat Science & Animal Biologics Laboratory. We have three more harvests planned over coming weeks as the celery plants approach maturity in early September. In the meantime, we will be on the lookout for emerging plant diseases tied to the increase in pest vector populations. Watch for more updates as we continue to develop optimal management practices for growing organic celery destined for the organic meat sector!
"This past fall, I started my graduate studies at UW Madison with Dr. Erin Silva as my advisor. I am pursuing a Master’s in plant pathology, and my research revolves around growing organic celery. Since last October we have been conducting a greenhouse pilot study investigating nitrogen uptake of the crop, using various organic nutrient amendments. We are interested in how timing between nutrient applications and harvest date affects nitrate accumulation. As we take samples of each treatment, we hope to identify methods conducive to producing organic celery with a nitrate level where it is worthwhile to juice these plants for powder. The data we produce, along with past research from the Silva team, will help us design our summer field trials."
The Organic Center is urging NOSB to recognize the development of an organic meat curing agent as one of its highest priorities, showcasing this "Organic Alternatives to Conventional Celery Powder" research project that is currently underway. Developing an organic meat curing agent has been among the research priorities listed by NOSB previously at its meetings, but the board removed it due to the OREI funding. TOC notes the research will take four years to complete, and stressed that NOSB needs to continue to include alternatives to conventional celery powder for curing organic meat in its research priorities until the research is complete and the need is met.
See the full press release here.
Look at all that celery!
Woohoo! Our project was awarded a full Organic Research and Extension Initiative (OREI) grant(link is external) from the United States Department of Agriculture (USDA).
Here is the non-technical summary(link is external) of the project: We will address current and future needs of the organic processed meat industry, particularly in the development of systems allowing for the increased production of organically grown celery powder and/or other crop alternatives that will benefit both the biology and economics of the organic crop rotations being used by farmers across the U.S. This addresses a critical and imminent issue facing the organic cured meat industry: the lack of availability of organic vegetable curing powder, which could impede further growth and potentially erode market shares. We propose to conduct vital research and extension activities to address these barriers facing the organic cured meat industry, bringing together a multiregional team of researchers, extension personnel, and industry stakeholders to establish a Working Group comprised of a "consortium of expertise" in organic horticultural and agronomic production, economics, and meat processing.
Long-term Project Goal: The long-term goal is to help establish fully organic sources of curing powders to expand markets for organic cured meat. Mid-term goals include 1) increasing the availability of organic vegetable curing powder by developing best management practices that result in adequate vegetable nitrate concentrations; and 2) confirming the efficacy of organic vegetable curing powders in commercial cured organic meat products, ensuring adequate quality and food safety. Through project activities, we will develop strategies across the supply chain to ensure an adequate quantity of curing powders from organically produced crops to meet the needs of the expanding organic processed meat industry without comprising system sustainability and environmental or human health. Read about other OREI awardees here.
The Organic Trade Association called for more research on organic alternatives to celery powder, in their comments to the National Organic Standards Board this week. Specifically, they noted that "there is a need to develop an organic alternative that is consistent with organic principles." They also called out their work with this project team through their Organic Celery Powder Working Group, noting that "the Working Group focused the first six months on establishing research partners, identifying funding opportunities and working in collaboration with the University of Wisconsin on the submission of a proposal for an Organic Research and Extension Initiative (OREI) planning grant. The planning grant proposal, submitted in early March 2016 and awarded later that year, helped to develop the roadmap of integrated research and extension activities needed to adequately address and overcome production challenges. An additional proposal to Farmers Advocating for Organics (FAFO) was also awarded." Read the full comments here.
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The Organic Center is a 501(c)(3) non-profit research and education organization based out of Washington D.C. Our mission is to conduct and convene credible, evidence-based science on the environmental and health effects of organic food and farming and communicate the findings to the public.