Occurrence and distribution of fungi associated with grapevine decline in Kurdistan region-Iraq

Abstract

A survey was carried out in five locations representing the main grapevine production areas of Duhok governorate-Iraq during 2008-2009 in four seasons, winter (Dec.-Feb.), spring (Mar.-May.), summer (Jun. – Aug.), and fall (Sept. – Nov.) Decline symptoms on grapevines included plants that failed to thrive normal, with reducing shoot growth and chlorotic interveinal areas that later became necrotic. In a cross section of grapevine arms, the internal wood tissues were frequently dark brown to black with a wedge-shaped necrotic sector. Severe symptoms were noted during spring to summer almost in all locations. Canes (bark and wood), buds, trunks or arms (bark and wood), and roots were sampled for fungal isolation. Fungal pathogens belonging to 18 genera were isolated from green growth and roots of the grapevine samples during the four seasons. Cylindrocarpon destructans, Neofusicoccum parvum, and Tognignia minima were the main trunk pathogens found in all grape-growing regions. These three species were reported for the first time in Iraq. N. parvum was isolated with a high frequency (98-100%) from wood of arms and canes in Bajelor and Badi locations during summer and fall. T. minima was found commonly in Zawita by 37-75% of isolation in the wood of arms and canes during fall. C. destructans was the most dominant root rot fungus and was frequently isolated from almost all locations particularly in Badi (41-75% of isolation).