A Superhero without a Cape: Using the Cover Crop Sunn Hemp to Feed the Soil, Suppress Nematodes and Smother Weeds

Final Report for FW05-314

Project Type: Professional + Producer
Funds awarded in 2005: $7,716.00
Projected End Date: 12/31/2006
Region: Western
State: Hawaii
Principal Investigator:
Hooks Cerruti
University of Hawaii
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Project Information


Even though cover crops rarely provide direct cash returns,
they're rapidly proving their worth as off-season crops for
helping to control insect pests, plant pathogens and weeds.
They also reduce soil erosion, improve soil structure and
nutrients and increase soil organic matter. This project is
intended to demonstrate
the value of sunn hemp as a cover crop in cucumbers. Field
trials of sunn hemp helped determine its impact on soil and its
effectiveness at helping to manage nematodes, insects and


The main cash crop of the farmer producer is cucumber. However, he was suffering a significant loss in marketable yields in this crop due to plant-parasitic nematodes. Additionally, the farmer producer had discontinued growing bitter melon a high value
crop because of continued crop failure. Subsequently, prior to initiation of this project it was determined that plant -parasitic nematodes were responsible for crop failure. The main goal of this project was to teach him and his laborers how to improve the economic viability of their farm by using the cover crop, sunn hemp as part of an integrated pest management system. Our main goals were to demonstrate how sunn hemp could be incorporated into his current production practices to concurrently improve soil health and
nutrient level, and help suppress weed and nematode pests.

Project Objectives:

1. Determine the impact of sunn hemp on soil and plant nutrient status.
2. Determine the effect of sunn hemp on key nematode, weed, and insect pest populations.
3. Quantify the impact of sunn hemp on vegetable productivity and marketable yields.
4. Encourage Hawaiian growers to produce their own sunn hemp seedsource.
5. Deliver an integrated, sustainable, and economically viable cover crop system to growers and educators.


Click linked name(s) to expand/collapse or show everyone's info
  • Khamphout Chandara
  • Declan Fallon
  • Koon-Hui Wang


Materials and methods:

See accomplishments

Research results and discussion:

Our results are being disseminated to vegetable growers beyond the cooperating producer through extension publications, farm site visits, web postings, and extension agents. In the past, Hawaii growers were given limited information regarding the use of cover crops for nematode management and thus mainly relied on nematicides and crop rotation for their management. However, crop rotation is not an option for those farmers with limited land and/or who grow a few crop types, and all or most are susceptible to similar
nematode species. Thus, sunn hemp offers an additional option. However, one of the leading constraints to greater adoption of sunn hemp and other sustainable practices into IPM programs for nematode management in Hawaii was the availability and
dissemination of information. Through our collaborative research and outreach efforts, we have started to disseminate more information to stakeholders on nematode biology and how sunn hemp can be used as a sustainable option for their management .

Since the beginning of the project, some growers have gained a better understanding of nematodes and the mechanisms by which sunn hemp and other cover crops can be used not only to suppress their population but increase soil health through the enhancement of
beneficial soil organisms. We now expect to see a reversal in a dependency on chemical nematicides. Two extension publications have been published and posted at the college website and an additional publication detailing results of the field experiment is being
prepared. Some of the work will also be presented at a symposium during the upcoming Entomological Society of American meeting. We are also refining our field methods to maximize the potential benefits of sunn hemp and increase farm profits.

Participation Summary

Research Outcomes

No research outcomes

Education and Outreach

Participation Summary:

Education and outreach methods and analyses:


Hooks, C.R.R, H.-H. Wang, and D. Falon 2006. An ally in the war against nematode pests: using sunn hemp as a cover crop to suppress root-knot nematodes. University of Hawaii at Manoa College of Tropical Agriculture and Human Resources, Plant Disease Publication PD-32. www.cthar.hawaii.edu/oc/freepubs/pdf/PD-32.pdf

Hooks, C.R.R, A. Fereres, and K.-H. Wang. 2007. Using protector plants to guard crops from non-persistent aphid-borne non-persistent viruses. University of Hawaii at Manoa, College of Tropical Agriculture and Human Resources, Insect Pest Publication IP-32. www.cthar.hawaii.edu/oc/freepubs/pdf/IP-32.pdf


McHugh, J. and L. Constatinides. Benefits of cover cropping in agricultural fields - Part 2. Wailua, Oahu, Hawaii. January 9, 2007.

Farm visits and consultations:

Aloun Farms
Alberta de Jetley LLC., Bennie's Farm
Harry Ige Farm
Khamphout Farm (Producer cooperator)

Education and Outreach Outcomes

Recommendations for education and outreach:

Potential Contributions

See Outcomes

Future Recommendations


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.