Biocontrol of Lettuce Drop Caused by Sclerotinia sclerotiorum and S. minor in Desert Agroecosystems

Abstract

Field experiments were conducted over 2 years in Yuma County, AZ, and Imperial County, CA, to determine the efficacy of several biocontrol agents for the management of lettuce drop caused by Sclerotinia spp. Commercial formulations of Trichoderma harzianum (Plantshield, Supersivit), Gliocladium virens (Soilgard), Coniothyrium minitans (Contans), and Bacillus subtilis (Companion) were evaluated and compared with the chemical fungicide iprodione (Rovral) against Sclerotinia sclerotiorum and S. minor. A single application of biocontrol products or of Rovral did not reduce lettuce drop caused by either Sclerotinia species. However, two applications of Contans, one at planting and one at post-thinning, significantly reduced the incidence of lettuce drop caused by S. sclerotiorum and increased yield but had no effect on S. minor at both locations in both years. Two applications of other biocontrol products did not significantly reduce disease incidence despite medium to high recovery following application. In contrast, Contans was only sporadically recovered following application. In vitro fungicide sensitivity evaluation revealed that both Trichoderma and Gliocladium species were tolerant to iprodione, dicloran (Botran), and vinclozolin (Ronilan) up to 1,000 ppm a.i., whereas both Sclerotinia spp. and C. minitans were sensitive to all three fungicides above 1 ppm. In summary, Contans was the most effective treatment for the control of lettuce drop caused by S. sclerotiorum, but no treatment was effective against S. minor in the desert lettuce production systems.

Bio-suppression of Sclerotinia Stem Rot of Tomato and Biostimulation of Plant Growth Using Tomato-associated Rhizobacteria

“…Biocontrol is eco-friendly, safe and may provide long-term protection to the crop. Reduced Sclerotinia Stem Rot incidence and severity have been demonstrated in numerous studies and successful disease control was achieved using fungi [10][11][12][13][14], bacteria [7,12,[15][16][17] or biofungicides [18][19][20] in many cropping systems. The most efficient bacteria used for Sclerotinia Stem Rot management belonged mainly to the genera Bacillus [1,9,[12][13]21], Pseudomonas [7,22], Enterobacter [23,24], Serratia [22,[25][26][27], and at a lesser extent Streptomyces, Burkholderia, Pantoea, and Paenibacillus [22,25].…”

Biological control of the soil-borne fungal pathogen Sclerotinia sclerotiorum –– a review

“…In most cases Pseudomonas showed multiple mechanisms in the biocontrol of diseases caused by S. sclerotiorum. Zazzerini 1987;Zhang and Fernando 2004a;Chitrampalam et al 2008;Hu et al 2011;Zeng et al 2012a, b;Monteiro et al 2013;Hu et al 2014;Kamal et al 2015 Bacillus megaterium Hu et al 2013;Hu et al 2014 Bacillus amyloliquefaciens Fernando et al 2007 Bacillus cereus Zazzerini 1987;Kamal et al 2015 Erwinia herbicola (Pantoea agglomerans) Godoy et al 1990b;Yuen et al 1994 Pseudomonas chlororaphis Zhang and Fernando 2004b;Savchuk and Fernando 2004;Fernando et al 2007;Selin et al 2010 Pseudomonas fluorescens Bin et al 1991;Expert and Digat 1995 Pseudomonas putida Expert and Digat 1995…”

“…Alternaria alternata Inglis and Boland 1992 Aspergillus niger Rai and Saxena 1975 Aspergillus ustus Rai and Saxena 1975 Coniothyrium minitans Tribe 1957;Huang and Hoes 1976;Turner and Tribe 1976;Whipps and Budge 1990;Budge and Whipps 1991;Trutmann et al 1980;Tu 1984;Huang et al 2000;Jones and Whipps 2002;McQuilken et al 2003, McQuilken andChalton 2009;Gerlagh et al 2003;Chitrampalam et al 2008;Jones et al 2011;Zeng et al 2012b;Bitsadze et al 2015;Jones et al 2015 Drechslera sp. …”

“…Trichoderma asperellum Geraldine et al 2013;Aleandri et al 2015 Trichoderma hamatum Aleandri et al 2015;Jones et al 2015 Trichoderma harzianum Bin et al 1991;Budge and Whipps 1991;Knudsen et al 1991;Menendez and Godeas 1998;Elad 2000;Chitrampalam et al 2008;Zeng et al 2012b;Steindorff et al 2014;Aleandri et al 2015 Trichoderma atroviride Li et al 2005;Matroudi et al 2009 Trichoderma koningii Castro 1995…”

Actinobactérias de biomas brasileiros: biodiversidade e potencial de uso na agricultura

“…Esses, em aproximadamente dez dias, podem produzir mais de dois milhões de novos ascósporos (De Freitas, 2012). Agentes de controle biológico (ACB) reduzem com eficiência os escleródios de S. sclerotiorum em vários cultivos (Budge e Whipps, 1991;Huang et al, 2000;Del Rio et al, 2002;Chitrampalam et al, 2008), como propõem Zeng et al, (2012). O controle de forma direta de S. sclerotiorum atacando os escleródios é uma destacada alternativa de manejo.…”