Occurrence of Grapevine Declines and First Report of Black Dead Arm Associated with Botryosphaeria obtusa in Lebanon

Abstract

Grapevine, cultivated mostly in the Bekaa Plain, is one of the most important fruit crops in Lebanon. During July 2004, a survey was made in 11 vineyards of local table or wine grapes to evaluate the sanitary status of the grapevine industry as far as wood declines are concerned. The most common grapevine decline was esca. The two forms of the disease (mild and severe) were observed. The mild form was characterized by leaf symptoms consisting of interveinal necrotic spots with yellow or red chlorotic blotches on white and red cultivars. The severe form was characterized by dieback of one or more shoots, leaf drop, shrivelling, and drying of fruit clusters. In west Bekaa, on cv. Cabernet Sauvignon, some vines showed symptoms identical to those of Eutypa dieback such as stunted chlorotic shoots with small, distorted leaves; moreover, symptoms corresponding to black dead arm (BDA) such as wine red spots on the margins of leaves and dry spots were seen as reported earlier (1). Diseased vines of various cultivars were collected: 10 Cabernet Sauvignon (7 esca, 3 BDA, and 1 Eutypa dieback), 4 Beitamouni, 3 Carignan, 2 Teifihi, 1 Zeitouni, 1 Mourverdre, 1 Caladoc, and 1 Merlot. In wood, cross sections through the trunk were made that showed mainly central necrosis, white heart rot, brown red wood, and black spotting. Wedge-shaped lesions were the least common. Particularly for BDA, peeling off the bark revealed a brown streaking of the external wood. Isolations were made on malt agar (MA) with wood chips cut from the different necroses described above. Fungal identifications were based on morphological characteristics in comparison with French isolates after subculturing at 20 to 22°C: Fomitiporia sp. (F85-1), Phaeomoniella chlamydospora (F85-2), Eutypa lata (BX1-10, 8D, and 8F), and Botryosphaeria obtusa (F99-1). The fungus most frequently isolated from central necrosis with white heart rot was the basidiomycete Fomitiporia sp. (35% of vines). Cultures of Fomitiporia sp. on MA reached 4 to 5 cm in diameter after 2 weeks and were yellowish to brownish without conidia. P. chlamydospora (associated with esca, black goo, or Petri disease) was isolated from only 9% of vines investigated. Cultures of P. chlamydospora on MA were slow growing and reached 7 to 8 mm in diameter in the dark after 8 days. Colonies were white but became light green and later became dark green. Sporulation was abundant. E. lata (causing Eutypa dieback) was isolated from the vine of cv. Cabernet Sauvignon showing typical symptoms and from two vines showing symptoms of esca only. Two strains produced characteristic pycniospores, and all strains were identified using polymerase chain reaction (Primer Scar 10A-10B) (2). Among the saprophytic fungi isolated from the different kinds of necroses, either central, wedge-shaped, or under the bark, B. obtusa associated with BDA was found most commonly (65% of vines). Cultures of B. obtusa were gray brown with dense aerial mycelium. Pycnidia started to form after 4 to 5 days and conidia (20 to 26 × 9 to 16 μm) were dark brown when mature. These results are consistent with previous descriptions. To our knowledge, this is the first report of black dead arm in Lebanon. References: (1) P. Larignon et al. Phytopathol. Mediterr. 40:S336, 2001. (2) P. Lecomte et al. Appl. Environ. Microbiol. 66:4475, 2000.

Fungal community associated with grapevine wood lesions in Lebanon

“…The trunk disease fungi found in this study were similar to the preliminary results reported in Lebanon (Choueiri et al, 2006) and with the results reported in Europe and in other Mediterranean countries (Armengol et al, 2001;Aroca et al, 2006;Larignon and Dubos, 1997;Luque et al, 2009;Mugnai et al, 1996;Péros et al, 1999;Péros et al, 2008;Rumbos and Rumbou, 2001) as well as in Africa (Berraf and Péros, 2005;White et al, 2011). The current study sampled from a larger area including the main grapevine growing areas such as West Bekaa, Central Bekaa and North Lebanon and the isolations were more comprehensive than those conducted by Choueiri et al (2006). New reports for fungal species on grapevines include D. mutila, N. parvum, B. dothidea as well as Pm.…”

“…To our knowledge, this is the first study using this classification method before microbial examination. The importance of grapevine in the Lebanese economy and the presence of trunk decline diseases in this country (Choueiri et al, 2006) have stimulated this survey. It also allowed us to observe the development of foliar esca symptoms (data not shown) during the summer of 2006 and to further demonstrate that leaf symptoms previously attributed to black dead arm (according to the description made by Larignon et al, 2001) in Lebanon (Choueiri et al, 2006) had been actually confused with those of esca (Lecomte et al, 2012).…”

“…Most of these studies pointed out the presence of many other fungi, of which Botryosphaeriaceae fungi are often reported. In the previous report done by Choueiri et al (2006), the only identified fungi found to be associated with esca and other declines in Lebanon were Fomitiporia sp., Pa. chlamydospora and Diplodia seriata ("Botryosphaeria obtusa").…”

“…But in recent years, the incidence of esca and grapevine decline has increased, resulting in reduced vigour and productivity and finally the death of branches or whole vines. A preliminary survey done in the West Bekaa valley in 2004 on 11 vineyards of local table or wine grapes (Choueiri et al, 2006) reported foliar symptoms of esca, eutypa dieback and black dead arm according to the description made by Larignon et al (2001). However, it was later demonstrated that foliar symptoms attributed to black dead arm are in fact esca symptoms in their initial stage of development (Lecomte et al, 2012).…”

Trunk Surgery as a Tool to Reduce Foliar Symptoms in Diseases of the Esca Complex and Its Influence on Vine Wood Microbiota

“… Ascomycota Cladosporiaceae E, P, S ■; ▲; ● 0.5; 9.1; 0.2 [ 28 , 88 ] Cladosporium sphaerospermum Ascomycota Cladosporiaceae P, S ▲ 1.1 [ 88 ] Cryptococcus sp. Basidiomycota Cryptococcaceae E, S ■; ▲; ● 0.3; 2.8; 0.2 [ 28 , 92 ] Diplodia seriata Ascomycota Botryosphaeriaceae E, P, S ■; ▲ 0.2; 0.3 [ 78 , 79 , 82 , 88 , 91 , 92 , 94 , 97 , 98 , 102 , 104 , 108 , 123 , 124 , 125 , 126 , 127 , ...…”