Integrating Plant Essential Oils and Kaolin for the Sustainable Management of Thrips and Tomato Spotted Wilt on Tomato

Abstract

Thrips-vectored Tomato spotted wilt virus is one of the most devastating pest complexes affecting tomato in the southern United States and elsewhere. Field trials were conducted over 2 years to determine the effects of volatile plant essential oils and kaolin-based particle films on the incidence of tomato spotted wilt and population dynamics of Frankliniella spp. thrips. The essential oils, geraniol (a monoterpene constituent of various plant essential oils), lemongrass (Cymbopogon flexuosus) oil, and tea tree (Melaleuca alternifolii) oil, were compared with a standard insecticide treatment and an untreated control. All treatments were applied with and without kaolin, in a 5 × 2 factorial design. Although the treatments did not clearly affect the abundance of vector species, there were treatment differences in the incidence of tomato spotted wilt. When combined with kaolin, the three essential oils reduced tomato spotted wilt incidence by 32 to 51% in 2005 and by 6 to 25% in 2006 compared with the control. In both years, tea tree oil plus kaolin reduced tomato spotted wilt as well as the standard insecticide treatments. Overall, kaolin significantly increased yield by over 26% compared to treatments without kaolin. When applied with kaolin, the three essential oils produced yields similar to the insecticide standard. Therefore, naturally occurring products, such as essential oils and kaolin, could be used successfully to reduce insecticide use on tomatoes.

Repellency of Essential Oils to <I>Frankliniella occidentalis</I> (Thysanoptera: Thripidae) as Affected by Type of Oil and Polymer Release

“…In the absence of kaolin, the incidence of TSW was only slightly lower in plots treated with essential oils compared with the experimental control. However, in the presence of the kaolin, the incidence of TSW by the end of the season was much lower than found in the control plots, with a maximum reduction of 51% being associated with the use of tea tree oil (Reitz et al 2008). One possible explanation for their results is that the kaolin slowed the rate of evaporation of the essential oils, extending the period of repellency.…”

“…Although this oil was highly repellent at the highest concentration tested (1%), it was relatively less repellent than certain other oils at lower concentrations. Reitz et al (2008) carried out Þeld trials in tomato (Solanum lycopersicum L.) testing whether any of three different essential oils would reduce the spread of tomato spotted wilt (family Bunyaviridae, genus Tospovirus, TSW), vectored by Frankliniella spp. Oils tested were geraniol, lemongrass (Cymbopogon flexuosus Spreng.)…”

Talaromyces wortmannii FS2 emits β-caryphyllene, which promotes plant growth and induces resistance

“…There are many reports that a mixture of volatile organic compounds (VOCs) from herbal plants protected crops from diseases or inhibited microorganisms directly (e.g., Chutia et al 2009;Kordali et al 2008;Reitz et al 2008). But which substance(s) in the VOCs contributes to plant protection and/or growth has been unclear.…”

Phytochemical Pesticides

“…Although plant secondary metabolites mediate a wide variety of complex interactions, some of these are released into the environment, mostly volatile or essential oil constituents, alcohol and aldehydes, ketones, esters, aromatic phenols, mono-and sesquiterpenes, etc., and others are produced in the plant for defense. In fact, during the last few decades, literature has been fl ooded with umpteen studies and comprehensive reviews (Arnason et al 2004 ;Champagne et al 1992 ;Copping and Duke 2007 ;Dev and Koul 1997 ;Harborne 1977 ;Isman 2005Isman , 2006Isman and Machial 2006 ;Koul and Dhaliwal 2001 ;Koul et al 2005a , b ;Nguefack et al 2007 ;Omar et al 2007 ;Parmar and Walia 2001 ;Reitz et al 2008 ;Rosell et al . 2008 ;Saxena 1987 ).…”