Crop Protection 134 (2020) 105170 Available online 8 April 2020 0261-2194/© 2020 Elsevier Ltd. All rights reserved. Integrated management of root-knot nematode (Meloidogyne spp.) in Florida tomatoes combining host resistance and nematicides Homan Regmi, Johan Desaeger * Entomology and Nematology Department, University of Florida, Gulf Coast Research and Education Center (GCREC), 33598, United States A R T I C L E INFO Keywords: Host resistance Fumigant Nematicide Meloidogyne spp. Solanum lycopersicon ABSTRACT Host resistance governed by the Mi gene is available in many commercial tomato cultivars, and is effective against the most common tropical root-knot nematode species (Meloidogyne incognita, M. javanica and M. arenaria). The resistance has some drawbacks like the lack of activity against other common root-knot nematode species like M. hapla and M. enterolobii, the widespread emergence of resistance-breaking races of M. incognita, and the reported heat sensitivity of the Mi gene. In Florida, many tomato felds often also harbour soilborne pathogens and weeds, such as nutsedge, together with root-knot nematodes. Therefore, most tomato felds in Florida are fumigated, and nematode-resistant tomato cultivars are rarely planted. Two feld trials were conducted during fall 2017 and spring 2018 to evaluate the potential of Mi-tomato cultivars in Florida, with or without additional use of a soil fumigant and/or nematicide. Root-knot severity in both seasons was signifcantly reduced in cultivars having Mi (Sanibel, Skyway, and Tasti Lee þ Mi), as compared to the cultivar without Mi (FL 47). Fumigation with chloropicrin at 225 kg/ha and nematicides (fuensulfone in fall and fuazaindolizine in spring) also signifcantly reduced nematode damage. This was mostly noted for the cv. FL 47, and mostly during the fall growing season, when early nematode pressure was higher. End-of-season root-knot nematode soil populations were signifcantly lower with Mi cultivars. Chloropicrin on the other hand tended to increase end-of- season root-knot soil populations. No breakdown of resistance due to high soil temperature (>30 � C) was observed. Soil fumigation signifcantly increased fruit yield, especially in fall (95% increase) and to a lesser extent in spring (14.5% increase), and mostly so for cv. FL 47 and cv. Sanibel. Overall, cv. Sanibel produced the highest fruit yields. 1. Introduction Tomato (Solanum lycopersicum L.) is one of the most valuable agri- cultural commodities worldwide. Globally, more than 177 million tons were produced in 2016 and the USA is the third largest tomato producer after China and India, with more than 13 million tons per year (FAO- STAT, 2017). Root-knot nematodes (Meloidogyne spp.) (RKNs) are one of the major pests affecting tomato production all over the world, espe- cially in tropical and subtropical regions. The three most common RKN species found in tropical and sub-tropical regions are M. arenaria, M. javanica, and M. incognita (Sasser and Freckman, 1987). Tomato crop loss due to RKN is diffcult to estimate, but losses of 50% or more are not uncommon, especially in warm climatic regions such as Florida where the nematodes can go through multiple generations within a season (Lamberti, 1979; Williamson and Hussey, 1996; Koenning et al., 1999; NASS, 2012). For decades, methyl bromide was the standard fumigant for man- aging nematodes, soilborne diseases and weeds in high-value crops such as fresh tomatoes in Florida. Since the phase-out of methyl bromide, Florida growers are now using other soil fumigants such as 1,3-D, chloropicrin and metam (Sande and Mullen, 2011; Noling, 2016; Desaeger et al., 2017). The reason for the widespread use of soil fumi- gants in Florida tomatoes is the need to not only manage nematodes, but also soil diseases and weeds. Also, at least until recently, other than oxamyl (Vydate L™), there were often no other nematicide alternatives. With the recent registration of fuensulfone (Nimitz®) and fuopyram (Velum®), and other new actives such as fuazaindolizine about to become registered, growers now have other options than fumigants to help manage nematodes. Whether these new nematicides will reduce the use of fumigants in Florida remains to be seen and will depend not only their capacity to control nematodes in Florida’s sandy soils, but also on the availability of appropriate non-fumigant disease and weed control * Corresponding author. Gulf Coast Research and Education Center, 14625 CR 672, Wimauma, FL, 33598, United States. E-mail address: jad@uf.edu (J. Desaeger). Contents lists available at ScienceDirect Crop Protection journal homepage: www.elsevier.com/locate/cropro https://doi.org/10.1016/j.cropro.2020.105170 Received 12 December 2019; Received in revised form 25 March 2020; Accepted 26 March 2020