Grapevine pruning time affects natural wound colonization by wood-invading fungi

Abstract

Grapevine pruning wounds made during the dormant season are a port of entry of woodinvading fungi. Timing of pruning may affect the wound susceptibility to these fungi, such as those associated with grapevine trunk diseases (GTDs). This study aimed to determine the effect of pruning time on natural fungal infection in six vineyards in Galicia, Spain, belonging to three Denominations of Origin (D.O) over two growing seasons. Pruning wounds were left unprotected physically and chemically during two periods of three months each, from November to February and from February to May. The diversity and composition of the fungal microbiome that colonized the pruning wounds was identified by ITS2 high-throughput amplicon sequencing (HTAS). A broad range of fungi was able to colonize grapevine pruning wounds at both infection periods. Fungal microbiome composition did not shift as year of sampling. Fungal communities were affected in their diversity and composition by the D.O., whereas the spatial variation (i.e. vineyard within each region) was low. Pruned canes harboured a core community of fungal species, which appeared to be independent of the infection period. Accumulated rainfall over 8 and 11 weeks after pruning positively correlated with the total fungal microbiome and in particular with the GTD fungal genus Diaporthe abundances. A strong seasonal effect on GTD fungal infection was detected for most genera, with higher percentages of abundance detected after pruning in February (winter) as compared with that of pruning in November (mid-autumn). In light of the GTD colonization results and given the environmental conditions and the geographical location of this study, early pruning is recommended to reduce the infections caused by GTD fungi during the pruning season in Galicia.

Above‐ground parts of white grapevine Vitis vinifera cv. Furmint share core members of the fungal microbiome

“…Similarly, Martinez‐Diz et al . (2020) found no significant differences between the diversity of fungal communities of grapevine wood samples in different sampling plots. Liu and Howell (2021) also reported that geographic location only slightly affected the microbial diversity and composition, except for fungal diversity associated with roots; however, regional and small‐scale variation in the below‐ground fungal microbiome is relatively common (Zarraonaindia et al ., 2015; Knight et al ., 2019; Deyett and Rolshausen, 2020).…”

“…Although various techniques are commonly used to assess OTU or amplicon sequence variant (Deyett and Rolshausen, 2019; Deyett and Rolshausen, 2020) numbers in fungal communities of grapevines using different primer sets (Pinto et al ., 2014) and sequencing techniques (Kernaghan et al ., 2017), our 853 OTUs of the filtered samples correspond to those of similar studies, in which the OTU number ranges between 200 and 2200 (e. g . Pinto et al ., 2014; Jayawardena et al ., 2018; Martinez‐Diz et al ., 2019, 2020; Fan et al ., 2020; Liu and Howell, 2021). Random subsampling of the samples to a few thousand reads is not unusual as seen in various analyses of fungal microbiomes of different above‐ground grapevine plant materials (Bokulich et al ., 2014, 2016; Pinto et al ., 2014; Fan et al ., 2020).…”

“…Martinez‐Diz et al . (2020) investigated wood‐inhabiting fungi of grapevines at three sampling times, November, February and May, in Spanish vineyards, and they found a correlation between fungal diversity and sampling time. Fungal richness and diversity were lower from February to May.…”

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

“…During the last two decades, different approaches to manage leaf stripe symptoms and to reduce vine death due to diseases of Esca complex have been tested and applied in the field. After the phasing out of sodium arsenite in the early 2000s, the applied tools for managing leaf stripe symptoms have been diversified, including pruning timing and modes, wound protection, remedial surgery and foliar treatments using biostimulants or chemical products [30][31][32][33]. Among the remedial surgery treatments, trunk renewal and trunk surgery are the best-known methods.…”

The Influence of Temperature on the Growth, Sporulation, Colonization, and Survival of Trichoderma spp. in Grapevine Pruning Wounds

“…An assay that evaluates the persistence of Trichoderma strains over a pruning wound will help to decide if these strains are suitable to be sprayed in field conditions. In order to reduce natural infection, early pruning (November) is recommended in combination with a biological or chemical wound protectant to reduce the risk of infection of Eutypa lata, Neofusicoccum parvum, Botryosphaeria dothidea, Phomopsis spp., Cryptovalsa ampelina, Phaeomoniella chlamydospore, Diplodia seriata [69], and the genera Botryosphaeria, Cadophora, Cryptovalsa, Cytospora, Diaporthe, Diplodia, Eutypa, Neofusicoccum, Phaeoacremonium, and Phaeomoniella [70] in comparison to late pruning (February) [57,58]. Moreover, delayed pruning may result in the sap-flow washing away any pruning wound protectant [53].…”