Download Adobe Reader


Professor-Vegetable Physiology- Vegetable Extension Specialist
Extension Administration office, Horticulture Program Team, Coastal Research and Education Center

Office: Clemson University CREC, 2700 Savannah Highway
Phone: 419-402-5394
Fax: Charleston, SC


 Educational Background

PhD Vegetable Crops
The Ohio State University 1993

MS Vegetable Crops
Cornell University 1979

BS Horticulture
Brigham Young University 1977


My appointment is 75% Vegetable Extension Specialist and 25% research in vegetable physiology and cultural practices at the Coastal Research and Education Center in Charleston. As an extension specialist in vegetable crop production, I have statewide responsibility for interaction with and advising vegetable growers on all aspects of producing marketable vegetable crops. This audience includes farm managers, greenhouse growers, and harvesting crews as well as owners and operators of each type of farm operation. I am also involved in working with the extension staff in teaching and educating our agents to deal also with the above clientele.
My research program deals with cultural practices of traditional and alternative vegetable crops in South Carolina (SC1700366). Currently my research and extension efforts are involved with evaluation of grafted melons, grafting methods and potential benefits to South Carolina growers and consumers. The major crops involved are: watermelon and cantaloupe.

 Research Interests

I am continuing to leading a grafting team of scientist that consists of the following people: Dr Shaker Kousik (USDA, Charleston SC), Dr. Pat Whecter, (USDA-ARS, Charleston, SC) Dr. Amnon Levi (USDA, Charleston SC), Dr. Kai-shu Ling (USDA, Charleston SC), Dr. Tony Keinath (Clemson, Charleston SC), Dr. Brian Ward (Clemson Charleston SC, Dr. Josh Freeman (University of Florida Quincy Fl), Dr. Jonathan Schulthesis (NC State, Raleigh NC), and Dr. Penelope Perkins-Veazie (NC State, Raleigh NC). The purpose of this time is to cover all aspect of cucurbit grafting from methods (myself), disease tolerance (Dr. Kousik, Dr. Keinath), virus resistance (Dr. Ling), breading material (Dr. Levi), rootstock resistance Breeding, (Dr. Wechter), field elevations (Dr. Schulthesis, Dr. Freeman, and myself) and post-harvest (Dr. Perkins). The overall objective of this team is to work together as one unit and come up with material that works best for the grafting procedure in the United States. Syngenta Vegetable seeds provided us with grafting material, seeds, and other equipment amounting in gifts of $40,000. They also provided a grant to work on the grafting methods in the amount of $50,000. Rootstock material was also provided from the following seed companies: Zeraim Gedera, Seminis, Harris Moran, Sakata, and USDA. We had 12 rootstock lines that we as a group evaluated in our specialty areas. It was my job to coordinate this effort. I did all the grafting and delivered all plants for each test. This past year was excellent. Progress has been made toward recommendations for the Southeast. We have published at 5 scientific papers that were peer reviewed in 2015-2016. This is the only team that I am aware of that is working together to cover all aspects of cucurbit grafting. We have developed a new grafting method that has gained national and international interest as a method that could greatly improve the efficiency of the grafting throughout the world.

 Extension and Outreach

Dr. Hassell continue to be a leader in the cucurbit grafting area and to promote South Carolina vegetables. He is known throughout the world in the area of vegetable grafting and spent time in Israel, (West Bank Area), Iraq, Australia, China, Korea, Japan, Taiwan South Africa, Myanmar and most recently Tajikistan teaching vegetable growers the art of grafting to control soil diseases. He helped develop a new grafting method to reduce labor costs which has a US patent. He was also involved in trips to Guatemala and Mexico to develop a grafting procedure that will benefit the watermelon growers in the United States by having affordable grafted transplants available to them in 2017. This has led to the development of a grafting company (TRI HISHTIL), an Israel based company, that construct a grafting plant in Ashville North Carolina that will started producing grafting transplants with a large enough volume to service the watermelon growers in the US 2017.
He has also developed a viable processing tomato industry within the state that is now produces over 200 acres of processing tomatoes and is currently involved in promoting sweet potatoes as a potential crop for South Carolina. He has also been heavily involved with the USDA to develop and promote a new line a mustard greens they developed that has tolerance to both races of the bacterial disease (Carolina Broadleaf) as well as a watermelon rootstock (Bulldog) that has both Fusarium resistance as well as root knot tolerance.
Research: Dr. Hassell is the leader of the cucurbit grafting team and has been a part of two federally funded grants with the most recent funded in the amount of 7 million. He was also be able to receive additional funding for his grafting work from Syngenta who will offer grafted transplants through their Full Count program in 2018
Administration: Dr. Hassell is currently serving as the Assistant Director of The Coastal Research and Education Center in Charleston, South Carolina. Dr. Ted Witwell is serving as the director form his campus location which has lead Dr. Hassell to take on the everyday duties of the research station. This past year they were able to make improvements to the station in the amount of over $350,000.


Refereed Publications

1.Daley, S.L. and R. L. Hassell. 2014. Fatty alcohol blinding causes watermelon rootstock seedlings to accumulate carbohydrates and increase in size. HortTechnology (In Press).

2.Daley, S.L., J. Adelberg, and R. L. Hassell. 2014. Improvement of grafted transplant quality over time by rootstock fatty alcohol treatment. HortTechnology (In Press).

3.Daley, S.L. and R. L. Hassell. 2014. Fatty alcohol application to control meristematic regrowth in bottle gourd and interspecific hybrid squash rootstocks used for grafting watermelon. HortScience 49(3):206-264.

4.Levi, A., J. Thies, P. Wechter, M. Farnham, Y. Weng, R. Hassell. 2014. USVL-360, a novel watermelon tetraploid germplasm line. HortScience 49(3):1-4.

5.A. P. Keinath and R. L. Hassell. 2013. On-farm evaluation of grafted seedless watermelon for control of Fusarium wilt race 2, 2012. Plant Disease Management Reports 7:V033.

6.Ling, K.-S., Levi, A., Adkins, S., Kousik, C. S., Miller, G., Hassell, R., and Keinath, A. 2013. Development and field evaluation of multiple virus virus-resistant bottle gourd (Lagenaria siceraria). Plant Disease 97:1057-1062 doi:10.1094/PDIS-07-12-0639-RE. (2012 Impact Factor = 2.455).

7.Keinath, A. P., and Hassell, R. L. 2013. Control of Fusarium wilt of watermelon by grafting onto bottlegourd or interspecific hybrid squash rootstocks despite colonization of the rootstocks by Fusarium oxysporum. Plant Dis.

8.Miller, G., A. Khalilian, J. Adelberg, H. Farahani, R. Hassell, C. E. Wells. 2013. Grafted watermelon root length density and distribution under different soil moisture treatments. HortScience 48(8):1021-1026.

9.Miller, G., H. Farahani, R. Hassell, A. Khalilian, J. Adelberg, C. Wells. 2013. Field evaluation and performance of capacitance probes for automated drip irrigation of watermelons. Agricultural Water Management 131:124-134.

10.Guan, G., X. Zhao, R. Hassell, and J. Theis. (2012). Defense mechanisms involved in disease resistance of grafted vegetables. HortScience 47(2):164-170).

11.Levi, A., J. Thies, K. Ling, A. Simmons, H. Harrison, R. Hassell, and A. Keinath. (2011). USVL-220, A novel watermelon breeding line. HortScience 46:135-138.

13.Kousik, C., R. Donahoo, R. Hassell. 2012. Resistance in watermelon rootstocks to crown rot caused by phytophthora capsici. Crop Protection 39: 18-25

14.Guan, W., X. Zhao, R. Hassell, J. Thies. (2012). Defense mechanisms involved in disease resistance of grafting vegetables. HortScience 47(2):164-170.

15.Levi, A., J. Thies, K. Ling, A. Simmons, H. Harrison, R. Hassell, and A. Keinath. (2011). USVL-220, A novel watermelon breeding line. HortScience 46:135-138.

16.Kousik, C., M. Adams, W. Jester, R. Hassell, H. Harrison, G. Holmes (2011). Effect of cultural practices and fungicides on Phytophthora Rot on watermelon in the Carolinas. Crop Protection 30:888-894

17.Keinath, A. P., Hassell, R. L., Everts, K. L., and Zhou, X.-G. 2010. Cover crops of hybrid common vetch reduce Fusarium wilt of seedless watermelon in the eastern United States. Online. Plant Health Progress doi:10.1094/PHP-2010-0914-01-RS.

18.Thies, J.A., J.J. Ariss, R.L. Hassell, S. Olson, C.S. Kousik, and A. Levi. 2010. Grafting for management of southern root-knot nematode, Meloidogyne incognita, in watermelon. Plant Disease 94:1195-1199.

19.Hassell, R., F. Memmott. (2010). Watermelon (Citrullus lanatus) Grafting Method to Reduce Labor Cost by Eliminating Rootstock Side Shoots. Acta Hort. 871:389-394

20.Dufault, R., B. Ward, and R. Hassell. (2009). Dynamic relationships between field temperatures and romaine lettuce yield and head quality. Scienta Horticulturae 120:452-459

21.Levi, A., J. Thies, K. Ling, A. Simmons, C. Kousik, and R. Hassell. (2009). Genetic diversity among resistance to root-knot nematodes, whiteflies, ZYMV or powdery mildew. Plant Genetic Resources 7(3):216-226.

22.Hassell, R., J. Schultheis, W. Jester, S. Olson, and G. Miller. (2009). In-row distance in triploid miniwatermelon cultivars affects yield and quality in diverse environments in the southeastern United States. HortTechnology19(3):538-545

23.Shepard, B., M. Shapiro, R. Hassell, M. Shaffer, C. Smith. (2009). Supplemental control of lepidopterous pests on BT transgenic sweet corn with biologically-based spray treatments. Journal of Insect Science: Vol, 9 Article 8

24.Davis, A., P. Perkins-Veazie, R. Hassell, A. Levi, S. King and X. Zhang. 2008. Grafting effects on vegetable quality. HortScience. 43:1670-1672.

25.Hassell, R., F. Memmott, and D. Liere. (2008). Grafting methods for watermelon production. HortScience 43(6):1677-1679