Rootstock (water) © 2001
Dr. Terry Bates

West Tier and phylloxera research projects discuss the advantages of C.3309 rootstock in terms of phylloxera resistance. However, root trenching of mature ownrooted Concord vines and Concord vines grafted onto C.3309 rootstock shows a significant difference in root distribution.

40-year-old Concord and C.3309 roots at the Cornell Vineyard Laboratory. Concord roots tend to spread out into the vineyard floor with a few roots growing down. C.3309 roots tend to grow down and not out. This root distribution pattern may explain why ownrooted Concord are more susceptible to drought and have a larger response to floor management and fertilization treatments.

During the dry weather conditions of 1999, the deep rooted C.3309 rootstock helped maintain good water relations and high photosynthetic rates in the Concord leaves.

Leaf photosynthesis of Concord vines during the height of the dry weather in 1999. Photosynthesis rates were lowest in ownrooted Concord vines grown in sod and highest in Concord/C.3309 vines. See the West Tier section for more information on these treatments.

Concord/C.3309 vines have bigger berries and lower brix -- is this true?

1. Shade effect? There is a tendency toward excessive vine size in Concord/C.3309 roots (possibly from deep phylloxera-free roots with good water and nutrient relations). Excessive vine size can lead to lower juice soluble solids because of canopy shading.
2. Dilution Effect? Concord/C.3309 tend to have bigger berries than ownrooted Concord. This takes on a different meaning in wet and dry years. In dry years, Concord/C.3309 vines maintain good water relations - the berries are full of water and leaf photosynthesis is good. Therefore, Concord/C.3309 has bigger berries and the same juice soluble solids as ownrooted Concord. In wet years, leaf photosynthesis is good for both ownrooted and grafted vines (sugar production is the same). However, Concord/C.3309 berries still tend to be slightly bigger in wet years which dilutes the juice soluble solids (slightly).
   This raises an important question for New York growers . . . Do we plant grafted vines for their superior performance in dry years (which are less frequent in New York) and manage for potential excess vigor, shading, and dilution in wet years? Or, do we stay with ownrooted Concord vines and find other means to maintain good water relations in dry years (floor management, irrigation, mulch)?
3. Soil type? The Fredonia Vineyard Lab is primarily a site of deep gravel/loam soil. C.3309 root growth is not restricted in any way and its deep roots can tap into a source of water. Water relations with C.3309 in terms of both berry size and leaf photosynthesis may change on a more restricted soil type.

New Rootstock Project!!!

Peter Cousins, USDA rootstock breeder, has initiated a cooperative rootstock project in the Lake Erie grape production region. The proposed project will test the performance of 10 rootstocks grafted with Concord on two different soil types.