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ARS Home » Southeast Area » Fort Pierce, Florida » U.S. Horticultural Research Laboratory » Citrus and Other Subtropical Products Research » Research » Research Project #431786

Research Project: Growing New Roots: Grafting to Enhance Resiliency in U.S. Vegetable Industries

Location: Citrus and Other Subtropical Products Research

Project Number: 6034-22000-043-016-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Jan 23, 2017
End Date: Dec 31, 2021

Evaluate rootstocks for the management of root-knot nematodes (RKN) and Fusarium wilt race 3 on tomato. Determine interactive effects of pest complex on resistant rootstocks and associated microbial communities. Evaluate available pepper rootstocks in a replicated, repeated on-farm experiment in a location with a history of Phytophthora capsici. Evaluate grafted pepper plant fertilizer requirements under controlled conditions in a greenhouse. Describe interactions between root-knot nematode (Meloidogyne incognita) infection and severity of Fusarium wilt and Phytophthora blight on selected cucurbit rootstocks. Collaborate on evaluation of nematode resistant cucurbit rootstocks.

Field trials will be conducted with a grower cooperator to determine the field performance of rootstocks reported to have both root-knot nematodes (RKN) and Fusarium wilt race 3 resistance. Incidence of Fusarium wilt in heirloom grafted plants using rootstocks with race 1&2 and race 3 resistance will be evaluated in a location known to have race 3 and isolates of the pathogen will be characterized as the disease occurs. In order to address the potential interaction between these two pathogens and the loss of nematode resistance, a series of controlled greenhouse experiments will be conducted. In each experiment, resistant and susceptible rootstocks, grafted to a susceptible scion, non-grafted, or self-grafted, will be inoculated with FOL race 3 prior to exposure to RKN, inoculated in the reverse order, or inoculated at the same time. This will be conducted with multiple levels of inoculum and with varying temperature conditions. Plants will be monitored for disease development, galling, nematode reproduction, and bacterial communities associated with both resistant and susceptible lines. The number of pepper rootstocks available for the management of Phytophthora crown and root rot could be increased through screening of accessions available from the USDA, ARS, Charleston, SC, as well as commercial rootstocks for which there is limited information available on potential for management of this disease. Available rootstocks will be evaluated in a replicated, repeated on-farm experiment in a location with a history of Phytophthora capsici. Grafted pepper plant fertilizer requirements will be determined under controlled conditions in a greenhouse. Plants will be grown in sand-culture and nitrogen rate, as part of a complete fertilizer, will be varied to 25%, 50%, 100% (control) and 200% of normal nitrogen application rate (200 mg·L-1 N). Leaf greenness via SPAD, growth index, pepper production, and plant tissue nutrient analysis will be determined over the course of the study or at harvest. Additionally, iron-efficiency, Strategy-I, reactions by roots to deficient iron conditions will be determined by measuring root rhizosphere acidification and root ferric reductase activity to assess plant response differences to micronutrient deficiency.