Ocorrência de nova doença do algodoeiro irrigado, no Brasil, causada por Sclerotinia sclerotiorum

Abstract

RESUMO -Em 1996, uma nova doença causada pelo fungo Sclerotinia sclerotiorum (Lib.) de Bary foi observada em algodoeiro (Gossypium hirsutum L.), cultivar Deltapine, irrigado sob pivô central, em Paracatu, MG. Os sintomas apresentados foram murcha e podridão da haste, do pecíolo da folha e da maçã, além de serem observados no interior do capulho micélio branco e escleródios escuros do patógeno. O teste de patogenicidade foi efetuado em algodoeiro, nas cultivares Deltapine e IAC 22, e em feijoeiro e quiabeiro, aos 14 dias de idade. As plantas foram incubadas em alta umidade durante 48 horas, a 25 o C. Três dias após a inoculação, verificaram-se sintomas severos de murcha e necrose dos tecidos, de onde o patógeno foi reisolado, completando-se, assim, os postulados de Koch. Este é o primeiro relato da ocorrência natural de S. sclerotiorum em algodoeiro no Brasil.ABSTRACT -In 1996, a new disease caused by Sclerotinia sclerotiorum (Lib.) de Bary was observed on cotton (Gossypium hirsutum L.) Deltapine cultivar irrigated under central pivot at Paracatu, MG, in the Savana region of Central Brazil. The symptoms were wilt, necrosis and rot. White mycelium and black sclerotia developed inside the boll. The pathogenicity test was done with two-week old cotton seedling cultivars Deltapine and IAC 22 and bean and okra seedlings. The plants were incubated at high humidity for 48 hours at 25 o C. Three days after inoculation, severe symptoms of wilt and necrosis were observed. S. sclerotiorum was reisolated from the damaged plant tissues, and Koch´s postulates were completed. This is the first report of S. sclerotiorum natural occurrence on cotton in Brazil.O algodoeiro herbáceo ou anual (Gossypium hirsutum L. r. latifolium Hutch) é uma malvácea fibrosa-oleaginosa, de grande importância sócio-econômica

Biological and chemical control of Sclerotinia sclerotiorum using Trichoderma spp. and Ulocladium atrum and pathogenicity to bean plants

“…Lithourgidis et al (2003) also noticed non-specific host of isolates obtained from bean and cucumber in leguminous trees, both inducing the symptoms in host under test. This pathogen has been associated to significant loss of commercial yield of crops of beans irrigated at the central region of Brazil (Charchar et al, 1999). In Pernambuco state, the incidence of white mold at the Agreste Meridional region of the state has been observed in small commercial cultivars (Miranda et al, 2002).…”

Cotton in Brazil: Importance and Chemical Control of Bolls Rot

“…Inside the capsule was observed a white, cottony mycelium and black and irregular sclerotia, that is, resistance structures of the pathogen (Charchar et al, 1999).…”

Reaction of brazilian cotton genotypes to white mold depends on pathogen aggressiveness and incubation conditions

“…de Bary, is becoming more important in Brazil, the fifth greatest producer and responsible for 10.5% of global exportation of cotton fiber COUTINHO, 2007;SUASSUNA, 2012;ABRAPA, 2017). Since its first report in 1996 in the county of Paracatu (state of Minas Gerais) (CHARCHAR; ANJOS; OSSIPI, 1999), the disease became widespread in crops under central pivot and in high altitude areas, due to cotton susceptibility and favorable environmental conditions for pathogen development, such as mild temperatures (18-25 ºC), high air relative moisture (>90%) and altitudes above 800 m (ABAWI; GROGAN, 1979;HALL, 1994;CHITARRA, 2008).…”

“…Symptomatic cotton plants present wilt, necrosis and rotting of stem, bolls, petioles and leaves. Whitish fungal mycelium can be found inside the bolls, with the sclerotia, dark colored resistance structures of irregular shape (CHARCHAR; ANJOS; OSSIPI, 1999;CHITARRA, 2007). Disease incidence and severity in the field can affect up to 30% of the crop production (SNA, 2014), with impact of up to $11.52 billion dollars.…”

“…Disease incidence and severity in the field can affect up to 30% of the crop production (SNA, 2014), with impact of up to $11.52 billion dollars. In this scenario, white mold has become detrimental to cotton cropping in Brazil, demanding constant attention from the farmer for proper management when the pathogen is found in the area (CHARCHAR;ANJOS;OSSIPI, 1999).…”