Improving the yield and quality of sweet potatoes grown in New York

Final Report for LNE10-292

Project Type: Research and Education
Funds awarded in 2010: $32,666.00
Projected End Date: 12/31/2012
Region: Northeast
State: New York
Project Leader:
Charles Bornt
Cornell Cooperative Extension Capital District Vegetable & Small Fruit Program
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Project Information

Summary:

Over 3 years of on-farm research funded by this project has resulted in the identification of 4 sweet potato varieties that appear to be more suited for our shorter seasons. We demonstrated planting double staggered rows on a typical 30” wide plastic mulched bed, 15 inches apart instead of a single row anywhere from 12” – 24”, results in more uniform root size and higher a quality roots. Of the eight growers surveyed at the beginning of this project, 5 of them have adopted double rows and 2 are experimenting with it on their own, while one has been doing it since 2010. This research was presented in 2012 to over 100 growers combined that attended either the Specialty Crops Session at the 2012 Empire Expo or the 3 hour intensive Sweet Potato School held in March of 2012 in Albany, NY. Within these two workshops we were able to document 28 new sweet potato growers through 45 surveys that were returned to us from growers that were in attendance. The combined acreage of these growers was approximately 9 acres and nearly all of them (90%) were planning on increasing their production in 2013. In addition to these growers, 10 additional growers that did not attend either meeting were given 50 to 100 slips to plant in the spring of 2012 and instructed on how to plant, care for and harvest the roots. Of the 10 growers given slips, 9 were very pleased with the results and said they would purchase slips in 2013 while 1 said they would not grow sweet potatoes in 2013 which was due to a marketing issue, not production. In January of 2013 we documented nearly a tripling of sweet potatoes slips sold to NY growers since 2009 (11,062 to 28,140 in 2012) by Scott Farms, whom we worked closely with during this project.

Introduction:

The increase in farmer’s markets, Community Supported Agriculture (CSA) farms, roadside market sales and the movement of “buying local” has growers looking to expand what crops they offer their customers. The increase is not solely with summer markets but also includes “winter markets”. Many of these growers, especially those participating in winter markets have indicated a need to offer consumers products other than storage vegetables such as potatoes, carrots and cabbage. Even though winter squash is a staple at these winter markets, it is becoming more difficult to grow a high quality squash, especially organically, due to the increased pressure from diseases such as Phytophthora blight, Downy and Powdery mildew, and virus. Sweet potatoes represent a potentially profitable alternative crop with seemingly less pest pressure in NY, and have led to growers evaluating them for production on their own farms. However, there is very little cultural information related to sweet potato production this far North.
In January, 2009, Jim Ballerstein, a research specialist at the NYS Agricultural Experiment Station in Geneva, NY, presented a sweet potato production talk to more than 100 growers at a meeting sponsored by Cornell Cooperative Extension Capital District Vegetable & Small Fruit Program. General sweet potato production techniques being used at the Geneva Experiment Station farm were discussed. At the conclusion of the meeting, growers were asked to fill out a survey in which one question asked, “What information did you learn today that will change how you produce vegetables on your farm?” Of the 38 respondents, 26 said they would try growing sweet potatoes.
In order to help growers answer these production questions, 3 years of on-farm research trials were designed to evaluate how to optimize root quality and yields: variety selection, use of plastic mulches (traditional black vs. Infra-red transmitting or IRT), floating rowcovers, transplants vs. traditional slips and plant populations or different planting configurations. Information was delivered to growers through formal meeting presentations, newsletters and one-on-one consultations.

Performance Target:

The objective of this project was to improve quality and production of sweet potatoes on 8 – 10 farms in the Capital District Vegetable and Small Fruit Program. Fifty additional growers will attend workshops and meetings and twenty of them will add sweet potatoes to their operations, helping diversity the industry.

We worked with 8 vegetable growers currently growing sweet potatoes as part of their crop plan. Of the 8 growers, all of them added at least two new varieties (Covington, O’Henry, and Beauregard) and 4 growers actually changed their variety selection completely from Georgia Jet and Centennial to Beauregard and Covington as a direct result of our variety trial studies. They have verbally reported that this has resulted in a higher percentage of marketable roots (less growth cracks and more uniform roots), but could not give specific yield data. All of these growers continue to increase their acreage according to how early they sell out of sweet potato roots in the winter. One doubled their acreage from 3 to 6 acres and another from 1 to 2 acres respectively.

In 2012, over 100 growers combined attended 2 specific meetings about sweet potatoes and at these workshops growers were given a survey with questions pertaining to sweet potato production. We received 45 surveys back from growers that were in attendance and 28 of the respondents indicated they would grow sweet potatoes in 2012.

Cooperators

Click linked name(s) to expand
  • James Ballerstein
  • Ted Blomgren
  • Jody Bolluyt
  • Jean-Paul Courtens
  • Brian Denison
  • Laura McDermott
  • Dr. Steve Reiners
  • Ron Samascott
  • Timothy Stanton

Research

Materials and methods:

In March of 2010, phone interviews were conducted with 8 growers that we knew were currently growing sweet potatoes for commercial production. They were all asked the same survey questions and their replies were recorded anonymously. The goal was to have a baseline as to the current production practices used by these growers. They were also asked what challenges they faced and continue to face with sweet potato production.

2010 On-Farm Research Trials:
In 2010, one on-farm research project was conducted at Samascott Orchards in Kinderhook, NY. All the slips of were purchased from Scott Farms, located in Lucama, North Carolina with the exception of the transplants that were used in one trial. The trial consisted of 4 different research objectives. All raised plastic mulched beds are approximately 4” tall with a 34” bed width (the amount of area that can be planted on) on a 6.5’ center and all have drip irrigation placed under the plastic. Grading size categories included Jumbo, (roots greater than 2.0 pounds), Large (roots between 1-2 pounds), small (greater than 0.25 pounds but less than 1.0 pound) and culls (included roots less than 0.25 pounds, less than 1 inch in diameter, misshapen, damaged etc.). See Figure 1 in Sweet Potato Figures Supporting File. These grading standards are the same as used by our host grower, Samascott Orchards.

Variety Trial: The following varieties were evaluated: Covington, O’Henry, Beauregard, Centennial, Georgia Jet and Carolina Ruby. Slips of these varieties were purchased from Scott Farms and planted in a single rows of slips spaced at a 15” in-row spacing(standard planting procedure according to our survey) on June 4, 2010 into either traditional black embossed or Infra-red transmitting (IRT) plastic mulch. Plots were 15’ long, consisting of 12 plants, replicated 3 times. Roots were harvested on September 30, 2010, cured and stored until November 23, 2010 when they were graded, counted and weighed.

Plant Density/spacing Trial: Slips of the Beauregard variety were planted on June 4, 2010 into either black or IRT mulch and spacing treatments were a single row at 15” down the center of the bed or a double staggered row 18” in-row spacing on the edges of the bed. Plots were 15’ long, or 12 plants each plot for the single row or 20 plants for the double row and replicated 3 times. Roots were harvested on September 30, 2010, cured and stored until November 23, 2010 when they were graded, counted and weighed.

Slips versus Transplants: This was a non-replicated trial due to the fact that we were not able to obtain our slips early enough to transplant them into plug trays and grow them out. Therefore we worked with a limited number of transplants that were grown by Jim Ballerstein at the New York Agricultural Experiment Station. Beauregard slips and 3 week old Beauregard transplants (planted on May 12, 2010 in 72 cell trays) were field planted on June 4, 2010 into IRT mulch in a single row at 15”. Plots were 15’ long or 12 plants of each treatment.

Plastic Mulch Study: The variety evaluation and slip spacing/density trials were all planted on both black plastic or Infra-red transmitting mulch in order to evaluate any differences in yield and quality between these two types of mulches.

2011 On-Farm Research Trials:
In 2011, two grower cooperators were asked and agreed to host several different sweet potato research trials. Unfortunately, slips that were ordered from Scott Farms located in North Carolina, in December for mid-May delivery were never received. Upon calling the company to find out what had happened, I was told that my order had been delayed and that there was a good chance it would not be shipped due to a shortage of slips in the major sweet potato production areas due to widespread flooding of already planted sweet potato crops. This resulted in a major shortage of slips for growers throughout the Northeast as southern growers purchased a majority of the slips produced for replanting. Fortunately, we did receive our slips, but later than we would have like to receive them but unfortunately not enough for two on-farm trials. Therefore, we decided to continue with the field trials at Samascott Orchards in Kinderhook, NY, the same location as in 2010.

Three separate trials were planted at Samascott Orchards: Infrared transmitting mulch (IRT) vs. standard black embossed plastic mulch with or without floating rowcovers, plant spacing/density trial and transplants vs. conventional slips. The variety Covington was used in all of these trials and was purchased from Scott Farms. All raised plastic mulched beds are approximately 4” tall with a 34” bed width (the amount of area that can be planted on) on a 6.5’ center and all have drip irrigation placed under the plastic. Grading size categories included Jumbo, (roots greater than 2.0 pounds), Large (roots between 1-2 pounds), small (greater than 0.25 pounds but less than 1.0 pound) and culls (included roots less than 0.25 pounds, less than 1 inch in diameter, misshapen, damaged etc.). These grading standards are the same as used by our host grower, Samascott Orchards.

Mulch Trial – IRT vs. Standard black embossed mulch with or without floating rowcovers: Sweet potato slips of the variety Covington were planted on June 10, 2011 in either IRT or black plastic mulch beds. Each bed contained a single row of sweet potato slips down the middle with an in-row spacing of 15”. Each plot consisted of 2 rows of IRT and 2 rows of black mulch and was 40’ in length, replicated 2 times. Floating rowcovers (DuPont 5131) were applied June 10, 2011 to half of the plots and left on except for being removed twice for weeding while the other plots were left uncovered. Roots were dug on October 20, 2011, cured and stored by Samascott Orchards until November 22, 2011 when they were graded, counted and weighed. See Figures 2-3 in Sweet Potato Figures Supporting File.

Slip Plant Spacing/Density Trial: Slips of the variety Covington were planted on June 7, 2011 into black plastic raised bed. Treatments consisted of slips planted in different spacing configurations including: single row down the center of the bed, 6” or 12” apart or a double staggered row of plants placed 8” from the edges of the bed at 12” or 18” in-row spacing. Plots were 15’ long and replicated 3 times. Roots were dug on October 20, 2011, cured and stored by Samascott Orchards until November 22, 2011 when they were graded, counted and weighed. See Figure 4 in Sweet Potato Figures Supporting File.

Transplants spacing vs. Conventional slips: On June 7, 2011 sweet potato slips of the variety Covington were planted in 50 cell transplant flats in the greenhouses at Samascott Orchards. These transplants were planted in the field on June 24, 2011 into black plastic mulch with one of the following configurations: a single row down the center of the bed, 6” or 12” apart or a double staggered row of plants placed 8” from the edges of the bed at 12” or 18”. Also on June 24, 2011, Covington slips delivered on June 21 and held were planted in a single row down the center of the bed 12” apart. Plots were 15’ long and replicated 2 times. Roots were dug on October 20, 2011, cured and stored by Samascott Orchards until November 22, 2011 when they were graded, counted and weighed. See Figures 5-7 in Sweet Potato Figures Supporting File.

2012 On-Farm Research Trials:
Plant Spacing/Density Treatments: Slips of the Beauregard variety were purchased from Scott Farms, Lucama, North Carolina and planted June 19, 2012 on raised beds (34” wide) with black plastic mulch and drip tape, spaced at 6.5 foot centers at Samascott Orchards, Kinderhook, NY. Treatments included double staggered rows planted 6, 12 or 18 inches apart (each row was planted in 8” from the edges of the bed) and single rows planted down the center of the bed at 6 or 15 inches. Plots were 15’ long and replicated 3 times. Plots were harvested September 10, 2012 and properly cured by our grower host. Roots were then graded according to root size and quality on December 10, 2012. Grading size categories included Jumbo, (roots greater than 2.0 pounds), Large (roots between 1-2 pounds), small (greater than 0.25 pounds but less than 1.0 pound) and culls (included roots less than 0.25 pounds, less than 1 inch in diameter, misshapen, damaged etc.). These grading standards are the same as used by our host grower, Samascott Orchards.

Research results and discussion:

Baseline Data: In March of 2010, phone interviews were conducted with 8 growers currently growing sweet potatoes for commercial production. They were all asked the same survey questions and their replies were recorded anonymously. These questions were used to develop a baseline of cultural practices used. The acreage of these 8 growers totaled a little over 13 acres with the largest acreage reported of 3.5 acres and the smallest was one acre. All of the respondents used black plastic mulch with one line of drip tape (0.45 gpm/100ft, 12” emitter spacing). All respondents used supplemental fertilizer with commercial blends, organic blends (granulated poultry manure) and compost. Rates varied between all growers with an overall average of 80 pounds actual nitrogen, 60 pounds actual phosphorus and 50 pounds of actual potassium. Three growers also indicated on the survey that they apply fertilizers during the growing season through the drip system. Only 2 growers used any kind of floating rowcovers and in both cases they used Reemay (0.5 oz/sq/yd). Growers reported purchasing slips from a number of sources: George’s Plant Farm, Steele Plant Company, Johnny’s Selected Seeds and Scott Farms. Georgia Jet was the most popular variety grown by all the growers followed by Beauregard then Japanese and Carolina Ruby. Most listed multiple suppliers during the conversation. All eight planted slips by hand with 2 reporting they punch holes with their waterwheel transplanter before planting. There was also a variety of spacing used with an overall average in-row spacing of 17.6” with a single row planted down the middle of the bed. One grower did indicate that he was using some double rows but did not elaborate on the details. Three of the eight growers used a potato digger or other type of root crop lifter to lift the sweet potatoes out of the soil but they all used hand labor to pick them up after they were lifted. The other 5 growers dug them all by hand using pitch forms. I was amazed that only 2 growers could actually give me fairly detailed yield information and it was based on the number of “bins” per acre. They told us they averaged approximately 15 bins per acre (averaged across all varieties) or around 10,000 lbs per acre. All respondents reported multiple marketing outlets that included CSA’s, farmers markets (including NYC Green Markets), retail stands, wholesale (to other growers, no supermarket chains) and restaurants with an average price overall was $1.40/pound (included all the markets above and all grades of roots). On average sweet potato roots were being stored until March/April, but most growers reported being sold out by this time of the season.

We also asked growers what areas they needed the most help or information about. 100% of the respondents wanted to see more variety information and how to produce roots earlier for market. Five reported they needed help with rodent control and 4 responded they needed help in developing a proper curing area for their roots. When prompted, they also agreed that plant spacing was also important.

Over 250 growers learned about the information generated by this grant through one on farm twilight meeting held in October 2010 and four formal lecture style meetings in January and February 2011 and January and March 2012. Over 500 growers were exposed to this information through two weekly newsletters covering nearly 18 counties in NYS.

One milestone that was not met within the timeframe of this award was the production of a short production bulletin or guide for sweet potatoes in NY. The development and writing of this bulletin is currently be developed and written and could be ready by May of 2013.

On-Farm Research Trials: The three years of on-farm research trials generated information that could easily be adopted by any sweet potato grower. According to most of our growers, the most desirable root is within the 1.0 to 1.5 pound range. We set out with the goal to determine variety and cultural practices that would maximize this size category of roots. We were not able to fulfill our goal of 3 on-farm trial cooperators for a number of reasons. We were able to complete 3 years of on-farm trials at one farm; Samascott Orchards located in Kinderhook, NY.

Variety Trials: In 2010 we evaluated 6 different varieties at Samascott Orchards in Kinderhook, NY. Of the six varieties, it was evident that the orange skin, orange fleshed varieties that performed the best were Beauregard and Covington (See Figures 8-9 in Sweet Potato Figures Supporting File). These findings were consistent with trials that James Ballerstein was conducting in Geneva, NY at the same time. These two varieties resulted in some of the highest marketable yields (See Table 1 in Sweet Potato Tables Supporting File), were the most attractive looking uniform roots compared to Centennial and Georgia Jet and Carolina Ruby (See Figures 10 - 12 in Sweet Potato Figures Supporting File). Beauregard and Covington also had better flavor in comparison to the other orange fleshed varieties. Georgia Jet resulted in a lot of total roots (highest jumbo roots), but also the highest unmarketable roots due to large growth cracks, twisted, very unattractive looking roots. Centennial appeared very pale in color and were quite variable in shape and size. Carolina Ruby has an attractive dark orange skin and flesh, but yielded very poorly in our trials. This is also consistent with what Jim Ballerstein reported in Geneva. O’Henry is a white skin, pale yellow fleshed variety that performed very well in this trial although we had no other white flesh varieties to compare it to (See Figure 13 in Sweet Potato Figures Supporting File). One thing that we noted was a large number of Jumbo roots, especially when grown on IRT mulch.

Plastic Mulches: In 2010 and 2011 we evaluated Infra-red transmitting mulch (IRT) compared to our standard black embossed plastic mulch. IRT mulch has been proven to increase earliness in crops such as melons and we hypothesized that may be it could improve the earliness of sweet potatoes as well. In 2010 we planted 5 of our 6 varieties on both types of mulch to determine if this was true and if variety had any influence (we did not have enough slips of Georgia Jet for both so it was grown only on the black mulch). IRT mulches resulted in the lowest number and weight of roots per acre in 4 of the 5 varieties (Beauregard, Covington, O’Henry and Centennial) whereas Carolina Ruby benefitted from being grown on IRT mulch (See Table 1 in Sweet Potato Tables Supporting File). In 2011, using the variety Covington planted in either IRT or standard black plastic mulch, we found that black mulch gave us the highest marketable root numbers, total weights and average root size across the different size categories compared to IRT mulches (See Table 6 in Sweet Potato Tables Supporting File). It is important to note that in 2011 we had one of the earliest and warmest springs and summers on record for the Capital District. Therefore we did not expect to see many differences in the two mulches. According to these research findings, black mulch would be the recommended mulch to use for sweet potato production.

Floating Rowcovers: In 2011 we evaluated the use of DuPont 5131 floating rowcovers to increase earliness and overall yields of sweet potato roots. We used Covington for this experiment and found that using floating rowcovers actually reduced overall yields and resulted in more “Small” sized roots compared to no rowcovers. In addition, we feel that rowcovers would not have increased earliness because they resulted in the fewest number of “Jumbo” roots (See Tables 5 & 7 in Sweet Potato Tables Supporting File). We believe that if plants covered with floating rowcovers produced early yields, they would have more “Jumbo” roots due to the fact that these roots would have been initiated first and sized up earlier. However, we also feel very strongly that leaving the floating rowcovers on all season is detrimental to the sweet potato plants by encouraging vine growth and not root growth (See Figure14 in Sweet Potato Figures Supporting File). Plots where rowcovers were left on were had visibly more vine growth than those plants left uncovered. We feel that rowcovers are probably most important at the beginning of the season after planting and possibly towards the end of the season when temperatures are starting to cool down. Although we have no data to support this, the correct recommendation for rowcovers might be to split the application time and apply it right after planting for 3-4 weeks, remove it and replace it mid-September to maintain warmer soil temperatures and give roots some additional degree days before being dug.

Transplants vs. Slips: Going into this research trial we were convinced that using transplants would solve all the production problems with sweet potatoes. However, using transplants proved to be somewhat of a hassle. First, getting the slip producers to send the slips early enough in the season (early May) was difficult. When talking with Scott Farms they indicated that that was the peak of the planting season for their growers in North Carolina and neighboring states and they basically did not have time to deal with any other customers at that time. Secondly, potting slips into the potting trays and then untangling them from one another during planting took additional time. This process increases the amount of labor needed to establish the crop which is in short supply during early June when growers are also trying to plant many of their other crops. In our 2010 un-replicated trial comparing slips and transplants, we found that transplants resulted in more “Jumbo” roots compared to slips which would indicate that if these plants were dug earlier, it might have resulted in more “Large” roots, which is our goal. However, slips still produced the highest number and weight of marketable yields. See Figures 15 – 17 in Sweet Potato Figures Supporting File and See Tables 2 & 9 in Sweet Potato Tables Supporting File)

In 2011 due to the lateness in which we received our slips and the lateness in the planting overall, we do not feel this data can be used. However, what it does indicate is that if you cannot get slips planted by the third week in June, your yields are extremely low and it probably not worth planting at that late date. The fact of the matter is that the extra management and cost of producing transplants may be greater than the returns in the number and overall yield of our “Large” category goals.

Plant Spacing/Density: Although not part of the original grant, it became very evident during the gathering of baseline data that using a single row of plants down the middle of a 30” – 34” wide bed was underutilizing that ground and plastic mulch. This became even more evident when you look at the traditional areas of sweet potato production where rows are planted anywhere from 32” – 42” apart and recommended in-row spacing between 8” – 10”. Therefore we decided to evaluate the use of different in-row spacing and planting configurations to maximize the mulch and beds we were making. According to our results, if you are looking to produce the highest percentage of “Large” size roots, a double staggered row 12” – 18” would be the recommendation. See Figure 18 in Sweet Potato Figures Supporting File. See Tables 3, 8, 10 & 11 in Sweet Potato Tables Supporting File)

Participation Summary

Education

Educational approach:

At a twilight meeting held on October 22, 2010 entitled “Growing for Winter Markets: Crops that can extend your season” at the Barber Farm in Schoharie County, we displayed representative samples of all six varieties that we trialed during the season and discussed our trial results to 25 growers in attendance. Many growers are still surprised that we can even grow sweet potatoes in our climate and are very interested in learning more. This meeting also resulted in several phone calls from interested growers wanting sweet potato cultural and variety information as a result of the above mentioned meeting.

In January 2011, 23 growers attended a meeting evaluating the use of crops that could be grown and stored for winter markets. A short presentation was given to the group on sweet potato production and information on variety selection and research from planting studies was discussed. On February 15, 2011, 110 vegetable growers attended the Capital District Vegetable and Small Fruit Growers Winter Meeting in which a presentation was given of the first year research results. In addition, samples of the varieties grown in the 2010 on-farm research trials supported by this SARE grant, we were available for growers to look at and discuss with project researchers during the conference. In the spring of 2011, an article entitled “Sweet Potatoes: What we have learned so far”, was included in the Capital District Weekly Update in which over 250 growers subscribe to. The article provided growers with detailed information about variety selection, plastic mulch recommendations and spacing options for different plant populations. This article was also used by Cornell Cooperative Extensions Cornell Regional Vegetable Program in their weekly newsletter called PestMinder, which is distributed to over 300 vegetable growers throughout 9 counties in western NY. This information resulted in 16 phone calls from growers around the region asking for more information based on the article.

On January 25, 2012, 75 growers attended a presentation at the New York State Fruit and Vegetable Expo Specialty Crops Session, summarizing the results of the first two years of sweet potato research generated by this grant. The presentation title was: “What we have learned about growing sweet potatoes”. This was a joint presentation given by Charles Bornt, Vegetable Specialist, Cornell University Cooperative Extension Capital District Vegetable and Small Fruit Program and one of our grant collaborators James Ballerstein of the NYS Agricultural Experiment Station, Geneva, NY. Growers were also asked to fill out a short survey in which we received 45 completed surveys back. On March 20, 2012, 22 growers attended the first Sweet Potato School in Voorheesville, NY. Presenters included Charles Bornt, Vegetable Specialist, Cornell University Cooperative Extension Capital District Vegetable and Small Fruit Program, Jonathan Schultheis, Production Specialist, North Carolina State University and Jack Osman Wellness Farm, Stewartstown, Pennsylvania. Growers learned more about the sweet potato industry and how slips are produced in North Carolina. They also learned more about different varieties, cultural practices and marketing outlets from sweet potato grower, Dr. Jack Osman in Pennsylvania. On April 2, 2012 the first two years of results were posted on the CCE CDVSFP website and can be found under the sweet potato tab at the following URL: http://cdvsfp.cce.cornell.edu/

No milestones

Additional Project Outcomes

Project outcomes:

Impacts of Results/Outcomes

  • Through initial phone interviews we were able to gain information on how growers were growing sweet potatoes in NY and more importantly, what gaps in production information or questions these growers had when it came to producing sweet potatoes. This initial survey was the springboard for us to develop research and educational needs for those currently growing and those that saw sweet potato crops as a new crop.

    Over 250 growers were directly exposed to information generated by this grant and an additional 500 were indirectly exposed. We gathered information from those growers directly exposed to this information using a paper survey at two different meetings. This is what we determined from these surveys:
    • Beauregard and Covington varieties are the most popular grown in NYS.
    • At the start of this grant, we had 1 grower reporting the use of double rows. Now 5 of the 8 original growers surveyed are using double rows instead of single rows.
    • All 8 of our initial survey members are planning on increasing their acreage in 2013.
    • From 45 surveys returned from two meetings, 28 indicated they had never grown sweet potatoes before but would in 2012.
    • In June of 2012 we were able to use funds from this grant to purchase a thousand slips of five different varieties which were divided up into 50 slips each of 3 different varieties and given to 10 different growers. Of the 10 growers given these slips, 9 have indicated that they will definitely grow sweet potatoes in 2013. They will use double staggered rows on black plastic with Beauregard, Covington and O’Henry and several indicated that after seeing Carolina Ruby, they would also try this variety due to its attractive appearance and regardless of the yields.
    • The number of slips sold to NY growers from one slip producer in North Carolina nearly tripled since the beginning of this grant in 2010.

    Most importantly we have shown that sweet potatoes are a crop that can produced in the Northeast with high quality roots that store well and give growers an additional item to sell at their markets. Even though an economic analysis was not done, extrapolating from our data would indicate that sweet potatoes could produce as much as 15,000 – 20,000 pounds of roots which at a $1.00/pound (average price across all size categories), gross sales could be $15,000 – $20,000. However, sweet potatoes represent a high labor requirement which should be considered carefully if growers are considering planting them. As our survey indicated, most growers are planting and harvesting by hand. Even those that have machines to aid in lifting the roots out of the soil require a lot of labor to get these roots from the field to the storage area. And there is the labor involved in grading, washing and packing them for market.

Farmer Adoption

As there is very little “local” information on sweet potato production for growers in New York, the information generate by this 3 year grant has been valuable for those growers. There has been a high rate of adoption/change in the varieties recommended in this report by seasoned and new growers as evidence in the number of slips sold into NY by just one supplier. We also have growers that have looked at the data on plant populations/densities and are no longer planting single rows of sweet potatoes down a 30” plus bed and are better utilizing that space with double rows. This allows them to continue to increase their yields and achieve better root uniformity that we have been looking for. I expect the number of growers trying sweet potatoes to increase while those already growing them to increase their acreage over the next 5 years.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

As sweet potato breeders continue to develop new varieties, they needed to be trialed on farms in the Northeast to determine if they fit within our growing season and have the quality roots growers are looking for. Information on fertility of sweet potatoes in the Northeast is also another area that needs research. Most growers do not have a good recommendations of what nutrients are most needed, rates or application timing. For example, in southern states 50 pounds of nitrogen is the recommended rate. According to our baseline survey’s, 80 pounds of actual nitrogen is the lowest reported. We know that high nitrogen fertility can increase cull roots due to growth cracks and miss-shaped roots. Plant populations and densities are also still not clear and may be influenced more by variety than anything else. Lastly, a good economic analysis of sweet potato production needs to be completed including detailed information on labor costs associated with planting, harvesting and marketing.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.