A new grafted rootstock against root-knot nematode for cucumber, melon, and watermelon

Southern root-knot nematode causes dramatic galling on the roots of cucurbitaceous plants such as cucumber, melon, and watermelon. Even low nematode levels can cause high yield losses. Control of root-knot nematode is usually based on soil fumigation with toxic methyl bromide. However, since methyl bromide is now banned, growers are looking for alternative pest control. A potential solution is to graft susceptible scions onto nematode-resistant rootstocks. Here, we selected a Meloidogyne incognita-resistant rootstock suitable for cucumber, melon, and watermelon scions. First, we screened the resistance against nematode and Fusarium. Then, we tested a wild Cucumis species, Cucumis pustulatus, as a possible rootstock for cucumber, melon, and watermelon scions. We measured the survival rate, plant growth, yield, and fruit quality of grafted plants. Fifty-three accessions from 16 species were studied. Five accessions exhibited high resistance to southern root-knot nematode, and 12 accessions exhibited resistance to Fusarium wilt. This research is the first study to report that C. pustulatus is a suitable rootstock with simultaneous resistance to root-knot nematode and Fusarium wilt for cucumber, melon, and watermelon. C. pustulatus rootstocks are thus promising for low-input sustainable horticulture. They should benefit to home gardeners, especially to those in areas highly infested with southern root-knot nematode.