Many growers know that grafting gives them access to much needed disease resistance – stronger resistance to some diseases than available in hybrids and more resistances than often found in them, too. Indeed, a quick scan of rootstock characteristics at http://www.vegetablegrafting.org/resources/rootstock-tables/ reveals that few commercial hybrid varieties of tomato or watermelon include some resistances found in rootstocks. However, the greater cost of grafted plants has many people asking how growers’ profits can be maximized when using them. Lowering costs and boosting yield and quality are key parts of the answer.
Best Management Practices (BMPs) are “how-to” guides used in commercial crop production. BMPs are developed over years of collaboration involving many people since they involve optimizing every aspect of individual production systems from site and variety selection through post-harvest handling, packaging, and delivery. Current vegetable BMPs are based on the use of nongrafted plants. However, grafted plants tend to be more vigorous than and different from nongrafted ones in other ways. More important, perhaps because of these differences, grower and researcher experience with grafted vegetable plants indicates that farm BMPs must be updated to lower the costs and maximize the grower profits associated with using grafted plants. Optimizing plant density (number of plants per acre based on in- and between-row spacing), and irrigation, fertility, and harvest management for many scion-rootstock combinations has become the focus of much on-farm and on-station research.
Four Ohio farms, The OSU North Central Agricultural Research Station (https://oardc.osu.edu/facility/north-central-agricultural-research-station), and OSUE will evaluate the effects of plant density using four scion-rootstock combinations in 2023. Drawing on previous work (e.g., https://u.osu.edu/vegnetnews/2021/08/21/grafted-watermelon-plants-under-what-conditions-and-practices-does-using-them-offer-the-best-return-on-investment/), plants provided by Tri-Hishtil of Mills River, NC (https://www.trihishtil.com/) will be set at a range of in- and between-row spacings affecting potential grower costs and, possibly, fruit maturation, yield, and/or quality. Within and across sites, the total plant population is expected to equal roughly 450 – 1,450 plants per acre in individual plots. The team is intrigued by the possibility that yield and quality will remain high in some treatments/plots although many fewer plants, rows, and various inputs will have been used.
We would like to hear from you if you have questions about making and/or using grafted vegetable plants or information on the topic. Please contact Matt Kleinhenz (kleinhenz.1@osu.edu; 330.263.3810).