WineGrape Advisory

Andy Allen
Extension Associate - Viticulture and Small Fruits
(919) 515-3705
andy_allen@ncsu.edu

Volume 1, Number 1
March 2, 2001

Time to Lime

Grapes are adapted to a wide range of soil types, from shallow to deep, sandy loams to clays, provided that soil drainage is good. A general rule of thumb is that the soil pH should be around 6.0 to 6.2, especially if you're planning on planting a combination of different types (ie - vinifera, F/A hybrids, American varieties). For new acreage, now is a great time to apply lime because it can be disked in if you're preparing the entire field or rototilled into the planting rows if you're only working up the soil in the rows. For established vineyards, lime can be surface-broadcast and allowed to move through the soil with rain or irrigation. Late winter/early spring is an excellent time to surface apply lime because the spring rains will begin moving it into the soil profile. Also, because lime moves very slowly through the soil profile, broadcasting a little every year is better than dumping a large quantity on the vineyard every few years.

While we're on the subject

One of the questions I'm asked by new growers is "When do you fertilize grapes?". Contrary to conventional wisdom, applications of synthetic fertilizers just before budbreak to support new growth are not very beneficial to grapevines. The reason is because grapevines do not begin active root growth until AFTER new growth has commenced. Research from around the world has confirmed that new growth in the spring is supported by nutrient reserves stored in the roots, trunk, and other permanent woody structures of the vine. Furthermore, grapevines prefer the nitrate form of nitrogen, which is highly mobile in the soil and therefore easily leached by spring rains. Current wisdom for commercial vineyards based on research in California and elsewhere is to apply fertilizers in the pre-bloom period. Where irrigation is not used, however, you still want to get fertilizer out early enough to be watered in by spring rains. Though not as well researched, fall fertilizer applications have not been shown to be any more beneficial or different from pre-bloom applications.

Other Pre-season Considerations

Bud swell and bud break are not too far off in the future now. An early season problem to be on the look out for as buds begin to swell is climbing cut worm damage. Cut worms are one-inch-long gray or brown larvae that climb up the vine at night to feed on developing buds. Damage will appear as hollowed-out buds, similar to grape flea beetle damage. In the day they hideout in soil or debris around the vine. Keeping vineyards free of debris may lessen the amount of damage, but will not eliminate it. Climbing cut worms are controlled by applications of Sevin, BT, or Guthion. Spraying late in the afternoon or near dusk just before the worms come out can increase effectiveness of the spray. For further information and pictures on the web, visit:

http://www.nysaes.cornell.edu:80/ipmnet/ny/fruits/grapes/grapesfs/cc/cc.html

New Tool for Vineyard Site Evaluation

An exciting new tool is about to be made available for vineyard site evaluation in North Carolina. The NC Grape Growers Council commissioned Mr. John Boyer of VA Tech to develop a computer program that will combine soil, climate, and geographic data for the entire state to produce recommendations on a site's suitability for grape production. This program will be delivered to us on March 8 and should enable us to make more accurate site evaluations with much more detail.

Upcoming Meeting

Wineries Unlimited - Lancaster, PA March 20-23.
For information on program and registration go to:
http://vwm-online.com/Events/WineriesUnlimited/WU2001.htm