|HOLLAND, STEPHEN - North Carolina State University|
|HOWARD, ADAM - North Carolina State University|
|HEITMAN, JOSHUA - North Carolina State University|
|GIESE, GILL - Shelton Vineyards|
|SUTTON, TURNER - North Carolina State University|
|AGAM, NURIT - Ben Gurion University Of Negev|
|BEN-GAL, ALON - Agricultural Research Organization Of Israel|
|HAVLIN, JOHN - North Carolina State University|
|Sauer, Thomas - Tom|
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/14/2013
Publication Date: 6/24/2014
Citation: Holland, S., Howard, A., Heitman, J.L., Sauer, T.J., Giese, G., Sutton, T.B., Agam, N., Ben-Gal, A., Havlin, J.L. 2014. Implications of an interrow fescue cover crop for below-canopy water dynamics in a North Carolina vineyard. Agronomy Journal. 106:1267-1274.
Interpretive Summary: Vineyards are carefully managed to produce high quality grapes for wine production. Water management is very important. At some times sufficient water is needed by the vines but at other times water is limited to improve grape quality. Evaporation from the soil between the vine rows affects the amount of water available to the vines and also affects the humidity in the vineyard. Humidity is a critical factor affecting several diseases. The objective of this study was to determine how row management (bare soil or grass) affects evaporation and humidity within the vine canopy. Measurements were made in a vineyard in northwestern North Carolina. There was greater evaporation from the grass but not enough to dry the soil and stress the grapevines. The greater evaporation did, however, increase the humidity in the vine canopy by an average of 2 and 5% based on direct measurement and model estimates, respectively. These results are of interest to growers and managers interested in management strategies to reduce disease outbreaks in vineyards.
Technical Abstract: Vineyard production in the southeastern U.S. faces challenges including poor internal soil drainage, high precipitation, and warm temperatures. This environment leads to significant canopy humidity, in turn, creating ideal conditions for fungal diseases. Maintaining fescue in the vineyard interrow is a common cultural practice in the region, believed to benefit grapevines by increasing competition for soil water and thereby reducing vine vigor. We hypothesized that, although interrow fescue may reduce soil water availability, it may also increase canopy humidity. Our objectives were to compare surface vapor flux from two treatments in the vineyard interrow (bare soil and fescue) and to asses any corresponding effects of vapor flux on below-canopy humidity. The surface vapor flux was measured with a micro Bowen ratio system. Below-canopy humidity was measured and also evaluated using a simple one-dimensional model. The surface vapor flux was greater for fescue interrow, compared to bare soil, by a daily average of 1.06 mm during the grape growing season. Although vapor flux was greater for fescue interrows, soil water depletion was insufficient to produce significant stress in the vines, as assessed by stem water potential measurements. Vapor flux from fescue interrows caused relative humidity to increase compared to the bare soil interrows by an average of 2 and 5%, based on measurements and the model, respectively. Data suggest that interrow fescue effects on below-canopy humidity may lead to a greater risk for grapevine fungal diseases in warm, humid environments.