Preventing post-harvest contamination of broccoli and other fresh produce is easier when equipment and packing sheds are built with food safety in mind. A new resource developed with support from the Eastern Broccoli project brings the principles of hygienic design to the post-harvest environment to show how incorporating the right features and materials can simplify cleaning and eliminate common hiding spots for pathogens.
Hygienic design is the norm for food processing environments, but surprisingly little attention has been given to applying the principles to post-harvest equipment and facilities that handle raw agricultural commodities. That omission caught the attention of Produce Safety Alliance Director and Eastern Broccoli collaborator Betsy Bihn, who engaged University of Vermont Agricultural Engineer Chris Callahan to develop guidelines that would make it easier for cooling and packing environments to be in compliance with food safety standards. The result is Hygienic Design for Produce Farms, which is available for download from Callahan’s blog and via a link on the Eastern Broccoli Production resource page.
The publication explains the five key principles of hygienic design (visible and reachable surfaces; smooth and cleanable surfaces; no collection points; compatible materials; and preventing contamination) and discusses some of the tools and materials that can be used to implement them in post-harvest operations. The main goals are to eliminate “harborage points” (places where contaminants and pathogens can settle) and to ensure that all surfaces are accessible and suited to regular cleaning and sanitizing. An “On-Farm Hygienic Design Checklist” is included in the publication and is also available in downloadable, stand-alone pdf and Excel formats.
The publication is intended for growers who are constructing or renovating their washing and packing operation. Agricultural equipment manufacturers will also find the publication useful, as it provides insights about the types of equipment improvements their customers need.
Late nitrogen application can cause early side-branch elongation, making the heads less desirable on the market. The top image shows a tight head with solid side branches. The lower image has a head that has begun to loosen at the sides. This effect can be reduced by having the last nitrogen application at least four weeks before harvest so that the growth rate is slowing down a bit just as harvest begins.
One of the challenges with raising broccoli in the East is getting heads to stay dense. In the warmth of summer, the outer branches of broccoli tend to start elongating a little before harvest maturity. They “blow up” in the words of many producers. The result is a head that doesn’t pack tightly in the box and has soft edges that are prone to damage in handling.
The solution is to let growth slow a little during the week before harvest. Growth is promoted by the combination of warmth, water, nitrogen, and sunlight. Warmth is a given for harvests in July and early August, sunlight we have no control over, and abundant water sometimes comes whether we want it or not. The main management tool is nitrogen.
Slowing growth by reducing nitrogen is a considerable challenge because abundant nitrogen is needed during the vegetative growth to get strong, healthy, fast-growing plants. The best approach is to supply nitrogen relatively early in the growing period, and not add nitrogen in the last four weeks.
Many popular broccoli varieties are harvested starting only eight weeks after transplanting. Therefore, the last nitrogen application should be only four weeks after transplanting. At that time, the foliage is near full cover, which a good time for a traditional side-dress application as well as cultivation to get escaped or newly germinated weeds. Fertigation through a trickle-irrigation system would be during the fourth week. At that time, the plants are large enough to take up the nitrogen but not so far along that excess growth at harvest will cause loose heads.
Applying all of the nitrogen before planting is a possibility. Ordinarily, applying 120 to 150 pounds per acre of nitrogen preplant is ill-advised because of the high likelihood of leaching before the crop takes it all up. However, because broccoli is only in the ground for about nine weeks through the end of harvest, and reaches its maximum uptake five weeks after transplanting, the risk of leaching loss is relatively low compared to the typical situation. Pre-plant application of the fertilizer opens up production options that don’t allow side-dressing or liquid fertilization.
This early-nitrogen approach is also helpful in reducing hollow stem. Hollow stem is likewise a symptom of excessive late vegetative growth. The main tool for managing hollow stem is adjusting the plant population. If hollow stem is a problem, it’s likely that both yield and quality will be improved by spacing the plants closer together. In New York we have found an in-row spacing of 8 inches to work quite well. But limiting late nitrogen also tempers the growth rate at the right time.
This article was published in VegEdge on June 5, 2019. A publication of the CCE Cornell Vegetable Program.
We have eagerly awaited the 2017 Census of Agriculture to see whether the Eastern Broccoli Project is having an effect. Today, the results were released, allowing us to compare our early effect (2017) with the pre-project baseline. We are happy to see so many more Eastern farms finding a place for broccoli in their crop mix.
Broccoli on muck soil gets a lot of nitrogen and water, and can grow very tall. Retired Cornell broccoli researcher Joe Shail provides the scale.
One consideration is that broccoli can get too big, and get hollow stem. Growers harvesting in the heat of summer find that making the last nitrogen fertilization four weeks before harvest helps avoid the excessive burst.
Some early varieties are maturing in 50 days in the summer. If you do the math, that means the last nitrogen side dress or fertigation is just three weeks after transplanting. Putting on ~150 lb/ac of nitrogen without burning the plants takes some planning.
Alternaria was widespread in the East this year. Unrelenting rain after mid-August created conditions in the Northeast that were conducive to this normally secondary disease. More important, the strain going around was not controlled by the most commonly used fungicide.
Alternaria lesions on head are deep. Even one renders the head unmarketable.
Christy Hoepting conducted a fungicide trial to test both our current fungicide program and new materials. Azoxystrobin (Quadris) is widely used, and a 2014 survey in New York showed no resistance. (Cornell pathologists Meg McGrath and Chris Smart are checking for known and novel resistance in 2018 isolates.)
This year, Tim Coolong reported in August that a Quadris-resistant strain was showing up in Georgia. Christy’s trial showed Quadris failing to control in New York. The good news is that the Alternaria was susceptible to fluxapyroxad and pyraclostrobin, the active ingredients in Priaxor. Priaxor is already labeled for use in New York, except Long Island.
The hot and humid weather with heavy rainfall from remnants of hurricanes during August was the perfect storm for Alternaria leaf spot (ALS) to rage out of control in brassica crops across Western New York in 2018. Cornell Vegetable Program fresh market specialists received several complaints about a disease that caused unsightly lesions on both leaves and marketable portions of brassica plants. When ALS attacks the head of broccoli or cauliflower, it renders them unmarketable. Hoepting visited with a grower who was planning to cut broccoli production by one-third, because he had just lost over 85% of his most-recent 5-acre planting to ALS head rot, a loss of $7,500. She immediately set up an ad hoc small-plot replicated trial on his farm in hopes of finding a fungicide that could control this devastating disease.
By the time the broccoli was ready to harvest, differences among treatments in side-by-side plots were striking. In the untreated check, 98% of the heads were unmarketable due to severe ALS, while the best fungicide in the trial, Merivon (fluxapyroxad and pyraclostrobin) had only 5% unmarketable heads. The fungicides that the grower had been using, Bravo and Quadris (azoxystrobin), resulted in 98% and 49% unmarketable heads, respectively. Commercially available fungicides Switch, Quadris Top and Endura had significantly lower unmarketable heads than Quadris with only 10 to 33%.
Priaxor can be applied at most 2 times sequentially and 3 times total. The only targeted fungicide that can be used with it in a program is Switch (cyprodinil and fludioxonil) because its active ingredients are in different chemical groups (FRAC groups 9 and 12) from those of Priaxor (7 and 11).
If the grower were to adopt a 4-week fungicide program with top-performing fungicides, he could expect to get at least 75% marketable heads. Compared to his Bravo/Quadris program, which only yielded 1470 pounds and net $1,323 per acre, the new program could increase both yield and net profit 5-fold by 5881 pounds and $5,562 per acre, despite a 5-fold increase in cost of fungicides from $44 to $223 per acre. After viewing the fungicide trial on his farm, the grower immediately adjusted his fungicide program to include the most effective fungicides in all of his remaining brassica plantings. He is planning to resume full broccoli production next year with the new fungicide program, which has potential to increase profit by $166,860 in his 30 acres of broccoli. Trial results will be shared with CVP growers over the winter, so all conventional growers can benefit from improved ALS control in their brassicas.
Alternaria leaf lesions with other diseases three weeks after one heavy rainfall event and regular showers afterwards
The Alternaria pattern can give false hope. There are lesions on older leaf, then clean younger leaves that grew after the big rain. However, the infection also affects the head.
For a 2014 survey showing all 47 isolates being susceptible to Quadris, see Kreis, Dillard and Smart. Plant Disease. http://dx.doi.org/10.1094/PDIS-03-16-0414-RE
Note added January 11: Today at the Southeast Vegetable Conference, Dr. Bhabesh Dutta of the University of Georgia at Tifton showed that the pathogen present in Georgia this year is a different (new) species of fungus that it is not controlled by azoxystrobin. Pathologists around the East are testing isolates from their regions to determine whether this species is the one that cause unusually high losses in the region.
This result is useful in that Dr. Dutta has already identified a fungicide program that should be effective in 2019. If the other azoxystrobin-resistant isolates turn out to be the new species, it mean that there has not been a change in the usual Alternaria.
Are you wondering what the implications of new food safety regulations are for broccoli production? Join Eastern Broccoli Food Safety specialists Chris Callahan, Betsy Bihn, and their colleagues on Monday, May 14 at 2 p.m. EDT for a webinar on “Produce Safety for Broccoli Producers”.
Topics will include:
An overview of produce safety
Coverage thresholds and compliance dates
The Food Safety Modernization Act and Produce Safety Rule
Broccoli-specific produce safety considerations
Overview and feedback on educational material development.
You can register for the webinar using the form below. Registration is not mandatory, but it will help us with planning and make it easier for you to get a direct link to the webinar via email. The form also has room for you to list specific questions that you would like to see addressed during the presentation.
The webinar is geared towards growers, but the information will also be useful to buyers, extension specialists, researchers, and others. Registrants will be emailed instructions for joining the webinar by the day of the event.
One fascinating thing about visiting Southwest Florida farms is seeing their distinctive seepage irrigation system. I had heard it described, but I didn’t really get it until I saw it in action.
Unique soils in Florida have allowed growers there to develop a an effective irrigation system that differs in many respects from what I have seen anywhere else. Sandy soils overlay a hardpan just below the maximum rooting zone. That situation allows lateral seepage of irrigation water over considerable distances with hardly any slope.
Main irrigation canals move water from water reserves in the abundant swampland to the fields. To irrigate a field, irrigation ditches are filled from those canals, then emptied when irrigation is done.
Irrigation water seeps sideways into the soil from the ditch. It reaches far enough that there are 12 beds between ditches. The water level is maintained precisely so that soil under the roots is wetted, but the roots are not drowned.
One of the significant advantages of this system is less disease. Because all the water stays underground, it is rarer for the foliage to be wet and the humidity, while naturally high, is lower. Thus the conditions for fungal spores to germinate and for hyphae to grow are considerably less common.
A couple other unique features make the system work. First, the land is very flat. Whole fields can be irrigated where the underground water table is maintained at an exact distance below the soil surface on the bed tops. In addition, field are interspersed with vast swamplands that serve as storage for irrigation water. Irrigation water can not only be drawn from these reservoirs, but it is also returned to them at the end of an irrigation cycle.
At the end of February, Project Director Thomas Björkman had a chance to visit Monica Ozores-Hampton’s trial site at the University of Florida’s Southwest Florida Research and Education Center and farmers in nearby Immokalee and Clewiston (between Lake Okeechobee and the Everglades).
The SWFREC has seven new faculty, which really adds energy. Like elsewhere in Florida, managing citrus greening is a big priority.
Monica Ozores-Hampton and her SWREC colleagues using infrared imaging to track crop growth by recording individual plants through the season.
The research station has recovered from Hurricane Maria last fall, with some new greenhouse facilities replacing ones lost. The fields at the station are set up to use the distinctive seepage irrigation system common in parts of Florida that have sandy soils with a hardpan. The crop in the Yield Trial is growing well and should produce good results for spring. The February days were 85°, so warmer spring weather will definitely test the adaptation of these hybrids.
Monica Ozores-Hampton’s yield trial at the UF Southwest Florida Research and Extension Center in Immokalee, Florida. The trial is on a sandy soil using a seepage irrigation system. This February day began at a balmy 70°F, which suited the students on spring break in nearby Ft. Myers just fine. But that night temperature is too high for broccoli reaching the most sensitive stage of development (and for winter-hardened Thomas Björkman, pictured). The grassy field edge runs along an irrigation ditch. In the morning, alligators like to come out of the ditch to sun themselves on the grass.
Vegetable farms in SW Florida are generally larger than elsewhere in the East. The smallest farm we visited raises a thousand acres of green beans and sweet corn. The land costs are moderate, and the sandy soil can be managed with appropriately scaled equipment. At this scale, vegetables reach large-scale buyers through the most prominent of eastern produce distributors.
The farms we visited all know very well how to raise broccoli efficiently. The bed system means that the plant populations are lower per gross acre than solid stands. Nevertheless, the yields have been good, pests are uncommon, and the labor has been available for harvest.
The main limitation has been access to markets. The growers noted some irony in being unable to interest south Florida buyers in local broccoli, but finding buyers in New York appreciated getting winter broccoli from closer by. A good relationship between buyers and sellers appears to allow many efficiencies that improve product quality and reduce costs.
Powell Smith, a founding member of the Eastern Broccoli team, recently retired from his position as Horticultural Program Team Leader for Clemson Extension to spend more time outdoors beyond the vegetable field. An entomologist with experience in industry and academia, Powell brought insights about southeastern agriculture and the agricultural community to the Eastern Broccoli project and served as lead for project-related Yield trials and outreach in South Carolina. Those responsibilities now transfer fully to Brian Ward, who has been working with Powell since 2016. No word yet on whether Brian will continue Powell’s habit of sharing sunny South Carolina weather reports with snowbound colleagues up north.
We thank Powell for all of his contributions to the Eastern Broccoli Project and wish him a long and joyful retirement. Happy kayaking, Powell!
Powell Smith, left, with Extension agent Zack Snipes at Powell’s recent retirement party. Photo: Cory Tanner via Brian Ward.
Photo 1. Broccoli plants in the second Hastings Quality trial planting, which was transplanted on 5 December 2015. The three center rows contain plots of broccoli hybrid entries, some of which have already produced crowns. Outer guard rows are planted to cauliflower.
The Eastern Broccoli Project recently expanded its Quality trial network to include a site in the important winter growing region of northeastern Florida. Lincoln Zotarelli oversees Quality trial plantings that run from October through April at the University of Florida’s Institute of Food and Agricultural Sciences (UF/IFAS) Hastings Agricultural Extension Center (HAEC).
The Hastings location is differs from other Quality trial sites not only in the timing of its production season, but also in the way in which water is managed. The very sandy soils in this region are separated from the underlying aquifer by a clay hardpan that sits within a few feet of the soil surface. This arrangement allows seepage irrigation to deliver water to plants from below the soil surface through the precise management of water table levels. All other Eastern Broccoli Quality trial sites rely on drip or overhead water delivery.
Florida Quality trial plantings this season were transplanted in early October 2017, early December 2017, and mid-February 2018. All three plantings included the same 31 broccoli hybrids that were rated at the four other Quality trial sites (in South Carolina, North Carolina, New York, and Maine) in 2017. Evaluations are complete for the first planting and in progress for the second planting (Photo 1, above). The third planting (Photo 2, at bottom) will undergo evaluation in early spring 2018.
The Hastings trial has already drawn public attention. In November, a group of 30 Florida elected officials touring grower farms in the Tri-County Agricultural area stopped by the UF-HAEC and, as part of their visit, heard a presentation on the Eastern Broccoli project and the importance of the broccoli industry to the northeast Florida economy. In December, an overview of the broccoli project and its efforts to identify new cultivars adapted to Florida conditions was presented to and discussed with 34 attendees of the station’s 2017 Cole Crop field day.
The Hastings site conducts the last set of plantings in the 14-month Eastern Broccoli Quality trial cycle that begins in February of the previous year. Already, the next Quality trial cycle has begun in Charleston, SC, where seed for a new set of trial entries was sown in February for transplant in mid-March.
Photo 2. Recently transplanted third planting of 2017-2018 Hastings, FL Quality trial. Red stakes mark plots on raised beds with centers spaced 40 inches apart. Between-plant spacing within a plot is 8 inches. Plants will be ready for crown evaluations in early spring 2018.
