Fungal communities of grapevine decline in the main grape-growing regions of Iran

Abstract

Grapevine decline is a worldwide problem of viticulture, leading to significant yield loss in the grape-growing regions of Iran. Several species of fungal endophytes are known as the causal agents of the disease. Vines with internal and external symptoms were sampled from Qazvin, Lorestan, North Khorasan and Razavi Khorasan provinces, showing different climate regimes. Regarding geographical regions with their variable climatic background, the cultivars, and vineyard age, the dominant fungi were different. In Bojnord, Phaeomoniella chlamydospora and Phaeoacremonium minimum, the known causal agents of esca disease, were the most isolated fungi obtained from 27 and 24 symptomatic plants, respectively. The establishment of Phaeomoniella and Phaeoacremonium species in Takestan and Tajareh might be prevented by different environmental and biological factors. Fomitiporia mediterranea isolates, the white rot agent, were isolated from Takestan with 25–30 years old vineyards, and the average summer temperature, precipitation, and humidity were about 1 mm, 25 °C, 38% respectively. In jovein with 15 years old vineyards, the most important esca related fungi, Phaeomoniella, Phaeoacremonium, and Fomitiporia species, were isolated in the summer, obtained from 31, 23 and 18 symptomatic plants, respectively. This study gives some insights into the possible relationship between grapevine decline related fungi and, especially, environmental factors, which leads to a more diffused picture of esca and the related fungi communities, making it challenging to clearly separate the effects of other factors.