Integrated Use of Grafting Technology to Improve Disease Resistance and Fruit Yield in Specialty Melon Production

Integrated Use of Grafting Technology to Improve Disease Resistance and Fruit Yield in Specialty Melon Production

Summary

Interest in production of specialty melons is increasing, particularly among small producers and organic growers. However, more research on yield performance and disease resistance of specialty melon cultivars is needed for quality production. In this study, ten specialty melon cultivars were evaluated under both conventional and organic production. Harvest date, marketable yield, fruit quality, and disease and root-knot nematode resistance were evaluated. Fusarium wilt and root-knot nematode infestations are among the most serious threats to sustainable production of specialty melons especially in the Southeastern U.S. Studies were conducted in Florida and South Carolina to assess the effectiveness of grafting with resistant rootstocks for Fusarium wilt and root-knot nematode management in grafted specialty melon production. New rootstocks were identified and tested in greenhouse and field experiments. Studies were also carried out to compare different grafting methods for grafted melon transplant production.

This annual report covers both 2010 and 2011 as the grant funding did not arrive until September 2010.

Objectives/Performance Targets

Objective 1. Identify effective rootstocks for managing Fusarium wilt and root-knot nematodes in grafted specialty melon production in the Southeastern U.S.

Objective 2. Examine grafting methods for specialty melon to improve survival rate and quality of grafted melon transplants.

Accomplishments/Milestones

The ten specialty melon cultivars evaluated in this study included: Ananas melons ‘Creme de la Creme’ and ‘San Juan’; Canary melons ‘Brilliant’ and ‘Camposol’; Asian melons ‘Ginkaku’ and ‘Sun Jewel’; Galia melons ‘Arava’ and ‘Diplomat’; and Honeydew melons ‘Honey Pearl’ and ‘Honey Yellow’. Muskmelon cultivar ‘Athena’ was included for comparison as the standard production melon. Cultivar evaluations were performed in spring 2011 at the Plant Science Research and Education Unit in Citra, FL. A randomized complete block design was used with 4 replications and 10 plants per cultivar per replication. The specialty cultivars demonstrated significant differences in marketable yield and fruit size, soluble solids content, and resistance to gummy stem blight, powdery mildew, downy mildew, and root-knot nematodes.

Melon grafted on ten selected Cucumis metulifer (African horned cucumber) rootstocks were evaluated for scion-rootstock compatibility in field trials in Charleston, SC. A number of these rootstocks were highly compatible with melon. Greenhouse studies were conducted to evaluate response of selected cucurbit lines against southern root-knot nematode (Meloidogyne incognita) in order to identify additional potential RKN-resistant rootstocks for grafted melon. Field studies were performed in Charleston, SC to examine the effect of an interspecific squash hybrid rootstock on production of six different types of melons.

A greenhouse study was conducted at the University of Florida to assess the resistance of C. metulifer and grafted honeydew melon with C. metulifer to Meloidogyne incognita race 1. A commercial cucurbit rootstock ‘Strong Tosa’ was also used for comparison. These results suggested that C. metulifer was highly resistant against M. incognita whereas grafting the susceptible melon scion onto C. metulifer did not affect its resistance.

Fifteen rootstock lines were screened for Fusarium wilt resistance/susceptibility in Charleston, SC. Both race 1 and race 2 isolates of Fusarium oxysporum f. sp. melonis were used for the screening study. Most of the test rootstock lines were found to be resistant, this is expected as many of these are not Cucumis melo (melon) and thus are not a host to this pathogen.

In the grafting method study, hole-insertion, one-cotyledon, and cotyledon-devoid grafting methods were compared by grafting ‘Athena’ cantaloupe onto three squash interspecific hybrid rootstocks. Rootstock suckers were developed in most grafted plants when using hole-insertion and one-cotyledon methods. However, plants grafted with these two methods showed significantly higher aboveground biomass compared with plants grafted with cotyledon-devoid method.

Impacts and Contributions/Outcomes

Compatible scion and root-knot nematode resistant rootstock combinations will be useful for managing root-knot nematodes in susceptible specialty melons in nematode-infested fields in the Southeastern U.S. Grafting with resistant rootstocks can also help effectively manage Fusarium wilt in specialty melons. The grafting method study will be continued to explore ways to decrease the amount of rootstock re-growth in grafted melon plants and to reduce the cost of the grafted transplant.

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