Prepenetration Stages of Guignardia psidii in Guava: Effects of Temperature, Wetness Duration and Fruit Age

Abstract

This study examined the effects of temperature and wetness duration in vitro and in vivo as well as the effects of fruit age on germination and appressoria formation by conidia of Guignardia psidii, the causal agent of black spot disease in guava fruit. The temperatures tested for in vitro and in vivo experiments were 10, 15, 20, 25, 30, 35 and 40°C. The wetness periods studied were 6, 12, 24, 36 and 48 h in vitro and 6, 12 and 24 h in vivo. Fruit 10, 35, 60, 85 and 110-days old were inoculated and maintained at 25°C, with a wetness period of 24 h. Temperature and wetness duration affected the variables evaluated in vitro and in vivo. All variables reached their maximum values at between 25 and 30°C with a wetness duration of 24 h in vivo and 48 h in vitro. These conditions resulted in 31.3% conidia germination, 33.6% appressoria formation and 32.5% appressoria melanization in vitro, and 50.4% conidia germination and 9.5% appressoria formation in vivo. Fruit age also influenced these factors. As fruit age increased, conidia germination and appressoria formation gradually increased. Conidia germination and appressoria formation were 10.8% and 2.3%, respectively, in 10-day-old fruits. In 110-day-old fruits, conidia germination and appressoria formation were 42.5% and 23.2% respectively.

Temporal progress and spatial patterns of quiescent diseases in guava influenced by sanitation practices

“…Spore germination was 11 % and appressorium formation was 2 % in 10 day old fruit. In 110-day old fruit, spore germination and appressoria formation was 43 and 23 %, respectively (Escanferla et al, 2009). It is possible that exogenous stimuli in ripe fruit influence the germination process of G. psidii conidia (Escanferla et al, 2009 The progress rates of anthracnose and black spot were higher when crop residues were present (p ≤ 0.05), which suggests that both pathogens can survive in these residues that perpetuate within-field inoculum in the absence of flowers or fruit.…”

“…The optimum temperature for infection by C. gloeosporioides lies between 22 and 25 °C (Piccinin et al, 2005). The optimal temperature for germination and formation of G. psidii appressoria ranges between 25 and 30 °C (Escanferla et al, 2009). Black spot in guava, found in fruit at 5.5 cm in length, was observed at high intensity in both plots when fruit reached maturation (Figure 2A).…”

“…The spores are dispersed by rain splashing combined with wind exposure (Singh, 2000). Spore germination and appressorium formation of G. psidii increase as the fruit ages (Escanferla et al, 2009). Nevertheless, knowledge of temporal and spatial analysis of guava diseases is limited but has the potential to provide important information for disease management.…”

Qualidade De Goiabas ‘Pedro Sato’ Em Função De Tratamentos Alternativos Em Pós-Colheita

“…dos sete tratamentos avaliados na primeira fase, quatro foram selecionados (fécula de mandioca, 1-MCP, termoterapia e etanol+cloro) para serem avaliados em associação de dois, aplicados de forma sequencial. na segunda fase optou-se por elevar a temperatura de armazenamento de 22 para 25 ○ C, de modo que a eficiência dos tratamentos fosse avaliada na condição ideal de desenvolvimento dos principais patógenos da goiaba (SOaReS et al, 2008;ESCANFERLA et al, 2009). Os frutos foram submetidos por oito dias a 25ºC e 80-85% de uR e avaliados quanto à qualidade físico-química e a incidência de frutos com podridões, conforme descrito na fase 1 da pesquisa.…”

Mode of Infection of Phyllosticta maculata on Banana as Revealed by Scanning Electron Microscopy

“…In Guignardia bidwelli, the causal agent of black rot in grapes, mycelial growth as well as conidial production is affected by environmental and nutritional factors with attachment to the substratum a prerequisite for germination to commence (Caltrider 1961;Shaw et al 1998). These processes in Guignardia psidii, causing black spot in guava fruit were also found to be affected by environmental conditions and fruit age of guava (Escanferla et al 2009).…”