Eradication of Sclerotinia sclerotiorum Sclerotia from Soil Using Organic Waste Materials as Trichoderma Fungi Carriers

Abstract

Sclerotinia sclerotiorum (Lib.) de Bary is considered as one of the most harmful soilborne pathogens, which reduces productivity of horticultural crops. Currently used chemical or biological methods for the eradication of S. sclerotiorum from a soil are not very effective. The aim of this study was to evaluate the possibility of eradication of S. sclerotiorum sclerotia from a soil using the Trichoderma isolates, which were multiplied on the organic carriers prepared from agro-industrial wastes and by-products: WsA (wheat straw + apple pomaces), WsP (wheat straw + potato pulp) and T-GRAN (dry onion rind, apples and strawberry pomaces, rapeseed meal). The results showed that soil amendment with organic materials overgrown with the Trichoderma fungi had a significant reducing effect on S. sclerotiorum. Especially effective was the carrier WsA overgrown with T. virens TRS114, which completely prevented the survival of sclerotia of S. sclerotiorum regardless of the dose of application. Less effective was the WsP carrier. However, addition WsP overgrown with T. atroviride TRS40 at the 5% w/v, resulted in survival only 6.7% of sclerotia. In the greenhouse experiments with lettuce, the application of granulates T-GRAN into the soil had different impact on S. sclerotiorum depending on the conditions to the pathogen development. In conducive conditions, an addition of the organic substances without Trichoderma significantly decreased the yield of lettuce plants. A positive effect on the growth of plants was observed after the application of T-GRAN overgrown with Trichoderma.

Emergência e análise ultraestrutural de plântulas de soja inoculadas com Sclerotinia sclerotiorum sob efeito da aplicação de Trichoderma harzianum

“…Eletromicrografia de varredura do estudo das interações entre Sclerotinia sclerotiorum e Trichoderma harzianum com as sementes de soja e entre si: A) Tratamento Testemunha: Fragmento de radícula de soja isenta de fungos; B e C) Tratamento com Sclerotiorum sclerotiorum (Ss) apenas, colonizando semente de soja em estádio de decomposição; D) Tratamento com Trichoderma harzianum (Th) apenas, colonizando radícula; E e F) Tratamento S. sclerotiorum com posterior aplicação de T. harzianum: micoparasitismo de T. harzianum sobre S. sclerotiorum em semente de soja. biológico contra patógenos de plantas é efetivo apenas em condições ambientais e em substratos favoráveis ao seu desenvolvimento e à sua atividade antagonística (10,13,22,27,31 Assim, as bandejas com areia utilizadas nos ensaios proporcionaram um ambiente rizosférico pobre em matéria orgânica, com baixa umidade, e provavelmente com uma comunidade microbiana de baixa diversidade e biomassa, o que pode reduzir a ação de T. harzianum em exercer antagonismo à S. sclerotiorum e promover melhor desenvolvimento vegetativo da planta.…”

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

“…Many experiments conducted all over the world demonstrated parasitism of S. sclerotiorum sclerotia and reduction of apothecia density by Trichoderma isolates (Geraldine et al 2013). Most of these experiments were conducted under laboratory or greenhouse conditions (Matroudi et al 2009;Smolinska et al 2016). However, the number of reports dealing with the antagonistic activity of Trichoderma in field conditions is rather limited Zeng et al 2012a;Geraldine et al 2013).…”

“…Suppressive effects of the organic amendments against soil-borne fungal diseases have often been attributed to enhanced microbial activity (Mazzola 2004;Borneman and Becker 2007;Bonanomi et al 2007). One of the methods for elimination of fungal propagules from infested soil is the application of organic material containing biological active compounds (Huang and Huang 1993;Gamliel et al 2000;Smolinska 2000;Huang et al 2002Huang et al , 2005Smolinska et al 2016). Volatile and non-volatile compounds formed during decomposition of these material in the soil may exhibit toxic effect towards many microorganisms.…”

“…The study by Huang et al (2002) reveals that amendment of soil with organic residues infested with C. minitans or Trichoderma virens decreased carpogenic germination of sclerotia. Furthermore, Smolinska et al (2016) reported that the application of selected Trichoderma species on organic carriers prepared from agroindustrial wastes (wheat straw, apple and strawberry pomaces, potato pulp, dry onion rind, rapeseed meal), allowed the complete eradication of S. sclerotiorum sclerotia. Organic compounds provide nutrients for mycoparasitic fungi which allows the maintenance of their population in the soil for a long time at a high level.…”

“…Bonanomi et al (2007), after analysis of about 2500 experiments, concluded, that in the case of S. sclerotiorum, the population of the pathogen increased in over 50% of the cases after addition of organic amendments. In conducive conditions for Sclerotinia, the addition of plant residues to the soil infested with sclerotia significantly decreased the yield of lettuce plants (Smolinska et al 2016). …”