Meteorological conditions determine the thermal-temporal position of the annual Botrytis bunch rot epidemic on <em>Vitis vinifera</em> L. cv. Riesling grapes

Abstract

&lt;p style="text-align: justify;"&gt;&lt;strong&gt;Aims&lt;/strong&gt;:&lt;/p&gt;&lt;p class="Tabelle" style="text-align: justify;"&gt;Under Central European climatic conditions, bunch rot caused by &lt;em&gt;Botrytis cinerea&lt;/em&gt; occurs virtually every season on &lt;em&gt;Vitis vinifera&lt;/em&gt; L. cv. Riesling grapes. Statistical investigations based on at least three annual disease severity assessments in 7 seasons (2007-2013) aimed at (i) simulating the disease progress and (ii) identifying meteorological conditions with predictive value for epidemics.&lt;/p&gt;&lt;p class="Tabelle" style="text-align: justify;"&gt;&lt;strong&gt;Methods and results&lt;/strong&gt;:&lt;/p&gt;&lt;p class="Tabelle" style="text-align: justify;"&gt;Sigmoidal regression models were used to describe the disease progress as function of thermal time. Coefficients of determination were &amp;gt; 0.97. The thermal time adjusted pace of the epidemic was almost constant in all seasons while the point of time when 5% disease severity was reached varied among years. Window pane analyses showed that relatively low temperatures and wet conditions during bloom as well as relatively high temperatures and low precipitation sums around/after veraison were associated with thermal-temporally late epidemics.&lt;/p&gt;&lt;p class="Tabelle" style="text-align: justify;"&gt;&lt;strong&gt;Conclusions&lt;/strong&gt;:&lt;/p&gt;&lt;p class="Tabelle" style="text-align: justify;"&gt;Environmental conditions determine the timing of annual bunch rot epidemics. Analyses indicate a strong link between meteorological conditions around grape bloom (probably affecting fruit set and cluster structure) and the predisposition of the grape clusters to bunch rot.&lt;/p&gt;&lt;p class="Tabelle" style="text-align: justify;"&gt;&lt;strong&gt;Significance and impact of the study&lt;/strong&gt;:&lt;/p&gt;&lt;p class="Tabelle" style="text-align: justify;"&gt;The enhanced understanding of the effect of environmental conditions on the bunch rot epidemics supports growers to optimize control measures and is supposed to result in a Botrytis bunch rot model.&lt;/p&gt;

Fungal Diseases in Two North-West Spain Vineyards: Relationship with Meteorological Conditions and Predictive Aerobiological Model

“…Despite this, the Botrytis incidence may endanger the fruit ripening as inoculum introduction can occur prior to these phenological stages [51]. Grey mould is able to infect vines at any stage [52], but flowering (S-6) may be more vulnerable since pollen release processes and sugary exudates present in flowers enhance the fungal colonization of vegetal tissues [53,54]. Some authors indicated that Botrytis conidia germination could occur at 13 • C [10], which explains the early infections that we detected during leaf development (S-1) at both vineyards in 2017.…”

Climate vs grapevine pests and diseases worldwide: the first results of a global survey

“…While rainfall is a key factor for the onset of grey mold (Molitor et al, 2016), other factors such as relative humidity and wind speed may favor Botrytis cinerea development on berries (Thomas et al, 1988). In dry climate vineyards, low temperatures are common (high thermal amplitude), possibly favoring dew development on berries.…”

What do we know about grapevine bunch compactness? A state-of-the-art review

“…In addition to these direct effects on fruit and wine composition, high pest or disease levels in the vineyard (particularly bunch rot) may force growers to harvest grapes at a stage of incomplete maturity, also affecting the final composition of grapes, musts and wines (Molitor et al ).…”