Cost benefit analyses of using grafted watermelons for disease control and the fresh-cut market

Authors: TAYLOR, MERRITT - OSU, LANE, OK; Bruton, Benny; Fish, Wayne; ROBERTS, WARREN - OSU, LANE, OK

Submitted to: Cucurbitacea
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2006
Publication Date: 9/15/2006
Citation: Taylor, M., Bruton, B.D., Fish, W.W., Roberts, W. 2006. Cost benefit analyses of using grafted watermelons for disease control and the fresh-cut market. In: Cucurbitaceae 2006, September 17-21, 2006, Asheville, North Carolina. p. 277-285.

Interpretive Summary: Two major influences on watermelon production and marketing have evolved in recent years. They are: (1) additional constraints on watermelon production by diseases and (2) the burgeoning fresh-cut fruit and vegetable market in the U.S. Watermelon diseases appear to be on the rise, in part, because of limited new land for watermelon crop rotation, loss of methyl bromide, and an increased incidence and severity of soil-borne diseases. Furthermore, there is generally insufficient resistance within the watermelon cultivars for adequate control of many soilborne diseases. At the marketing end of the watermelon industry, fresh-cut fruits and vegetables sales have risen to $15 billion annually. Maintaining a high quality fresh-cut watermelon fruit product remains a significant challenge to processors. At the Lane Research Station, Lane, OK, we initiated a comprehensive yield, quality, and economic evaluation of grafting watermelon onto gourd or squash rootstocks for both the control of soilborne diseases and the effect on fruit quality. Yields of grafted plants were generally equal to or greater than the non-grafted plants. Fruit sugar content, measured as soluble solids, was affected minimally, if any, by grafting. Lycopene content of fruit from grafted plants was equal to, or marginally better than, fruit from non-grafted plants. Lycopene imparts the red color to watermelon and is highly beneficial to human health. Certain combinations of watermelon cultivar and rootstock were significantly superior to other combinations. Fruit firmness was two times greater in the grafted fruit than in the non-grafted fruit, even after 10 days of cold storage as fresh-cut fruit. Thus, there is potential for these grafted plants to have an increased demand by the cut-fruit industry due to the superior quality of the flesh. The cost to purchase a grafted seedling plant from a seedling supplier currently would be approximately $0.75 per plant, which would include the cost of the seed and the grafting operation. Non-grafted seedless plants cost approximately $0.28 per plant. Assuming 1,500 plants per acre, grafted seedless transplants would cost approximately $705.00 per acre more than the non-grafted plants. Calculations indicate that a farmer producing 25,000 pounds of watermelon per acre would be breaking even at $0.08/lb with non-grafted transplants but would need $0.11/lb to break even with the grafted transplants. Thus, the farmer with an expectation of producing 25,000 pounds per acre would need a pre-plant contract assuring him of a minimum price of $0.11/lb to justify risking the extra $705/per acre cost required when planting grafted transplants. This then means that the fresh-cut processor would have to be willing to assure the farmer of a premium price of $0.02-$0.03/lb for his melons so that the processor, in turn, could provide a superior product to his customers.

Technical Abstract: Soil-borne diseases such as Fusarium wilt continue to plague watermelon growers in intensive production areas where land resources are scarce and rotation of various crops is limited. Risk management alternatives, available to the farmer, have been reduced by the loss of soil fumigation chemicals such as methyl bromide. Grafting of watermelon onto resistant rootstock has been found to provide effective resistance to Fusarium wilt but at an increased cost of production. There is potential for these grafted plants to have an increased demand by the cut-fruit industry, in the long-run, due to the superior quality of the flesh. Fruit from certain scion/rootstocks may even bring a premium from the cut-fruit industry as they are recognized for their superior shelf life and firmness of flesh. The resistance of these plants to soil-borne diseases provides the farmer a viable risk management strategy as an alternative to methyl bromide as a means of disease control.