2006 Research Reports
Wine Production Assessment of Clonal Trials, Cab Franc Training, IBMP and Experimental Breeding Program Selections
G. Stanley Howell, Jon Treloar
Abstract: In order to understand the impact of various viticultural treatments on wine quality, individual wines from the 2005 clonal, training system/shoot density, experimental breeding and methoxypyrazine reduction trials were produced. The exceptional growing season ripened all varieties, producing outstanding varietal characteristics across all varieties. However, the unseasonably warm vintage masked most of the treatment affects that might otherwise be seen in an average year. Yet differences in methoxypyrazine concentration were seen based on the timing of leaf removal, as well as the clone of Cabernet Sauvignon. All of these wines have been added to the Department of Horticulture wine library for further evaluation.
Controlled Cultural Reduction in Fruit Set and Subsequent Harvest Season Botrytis Cluster Rot
G. Stanley Howell, Conrad Schutte, Jon Treloar
Abstract: Controlled leaf removal at trace bloom over 5-years reduced fruit set in a range of small, tight clustered wine grape cultivars with a concomitant reduction in harvest season sour rot development. Year-2 effects were negative as the buds at nodes of the leaf removal sites were less cold hardy and much less productive. This negative response was overcome for training systems employing cane pruning as fully foliated, non-fruiting canes were retained at the head as year-2 bearers. Employment of several photosynthesis (Pn) inhibiting sprays created short-term Pn reduction, but were insufficient to create the source-sink imbalance analogous to leaf removal and showed no reduction in fruit set.
Crop Estimation and Sampling to Achieve Optimal Fruit Maturity and Quality Under Michigan Conditions
G. Stanley Howell, Conrad Schutte, Jon Treloar
Abstract: The use of long-term berry weight averages to predict berry or cluster weights and thus final harvest weights was rejected due to: 1) year-to-year variation greater than 100%; 2) seasonal variation in fruit set; and 3) cluster weight variation due to spring frosts. Using the growing degree days (GDD) at which the berry is at 50% final weight has been shown to be a useful estimator of final harvest weight over three very different seasons. Importantly, the GDD (base 50F) for individual varieties varies for that variety. Most are near 1200 GDD, but a few are 1400 to 1700. The method, employing 3-vines at the appropriate GDD, used to predict final yield was quite good for a very different year like the 2005 season. Of the 10 varieties in the test, three were within ½ ton of the prediction, and six others were less than 1.5T/A off. We would like to be within 0.75 T/A for all varieties, and this will require refinement of the methods, likely an increase in the number of predictor vines from three to six or more.
Cellar Methods to Reduce Methoxypyrazine Levels in Cabernet Franc & Cabernet Sauvignon Wine
G. Stanley Howell, Jon Treloar, Randy Beaudry
Abstract: In cool climate wine growing regions such as Michigan, the limitations of a shortened growing season can make ripening Merlot, Cabernet Franc, & Cabernet Sauvignon problematic. As a result, fruit may be harvested with under-ripe green bell pepper flavors caused by excessive levels of 3-isobutyl-3-methoxypyrazine (IBMP). This study focused on the utilization of specific cellar practices to reduce the IBMP levels below the human detection threshold. Yeast choice had a significant affect on the IBMP concentration of the resulting wine, while malolactic bacteria choice had less of an impact. The addition of enzymes and oak chips did not result in a clear difference in IBMP concentration.
Influence of Training System Choice and Shoot Density on Yield, Yield Components and Fruit Composition of Cabernet Franc Grapevines
G. Stanley Howell, Conrad Schutte, Jon Treloar
Abstract: Cabernet Franc grapevines in SW Michigan were subjected to five different training systems and three levels of shoot density over the period from 2000 to 2005. The systems that were most acceptable were Guyot and Low Cordon trained to a VSP trellis. The Sylvoz system was excellent also, but the lack of adaptability to the "spare parts" concept, central to maintaining productivity under Michigan's conditions of frequent winter kill to the snow line, limits its utility to Michigan growers. The yield and fruit composition data suggest the utility of the 10-shoots/meter treatment, yielding in excess of 4 T/A. NOTE: That tonnage is based on zero vines missing/acre; 4 T/A when 50% of vines are missing is cropping vines at 8T/A. Grapevines, produce yield, not acres.
Systemic Insecticides for Selective and Targeted Insect Control in Michigan Vineyards
Rufus Isaacs, Steve Van Timmeren, John C. Wise
Department of Entomology, Michigan State University
Abstract: Systemic insecticides were applied to the root system of hybrid grapevines using a chemigation system, to determine their effectiveness at controlling potato leafhoppers. Applications in early June provided about 3 weeks of protection against this damaging pest, with Admire, Platinum, and Belay all providing high levels of control. These treatments did not protect vines against Japanese beetles, probably because the applications were too early for this pest. Comparison of different timings of application indicated that applications in early June were more effective than in late June. We are continuing to measure the effect of these soil treatments on non-target insects and nematodes in the soil.
Improving Control of Phomopsis Fruit Rot in Vignoles Grapes
Annamiek Schilder
Original Goals and Objectives: The goal of the project was to improve control of Phomopsis fruit rot in 'Vignoles' grapes and the specific objectives were to:
1) Determine tissue specificity/virulence of Phomopsis viticola isolates from 'Vignoles' vineyards
2) Evaluate the efficacy of late-season fungicide sprays against fruit rot development and simultaneously monitor spore release at the site.
A Strategic Screening Program for IR-4 Registration of Insecticides in Grape
John C. Wise, Rufus Isaacs
Department of Entomology, Michigan State University
Abstract: As a result of the 1996 Food Quality Protection Act (FQPA) the EPA is likely to eliminate or severely restrict many of the conventional pesticides (i.e.; organophosphate and carbamate insecticides) traditionally relied upon for fruit production. Because of these circumstances, minor-use crops, like grapes, may be left with a significant short-fall in pest management tools for the future. The USDA IR-4 project serves as the primary avenue that pesticide chemistries, not fully supported by their parent manufacturer, can be registered for minor-use crops. A strategic grape-pest chemical screening program has been established at the Trevor Nichols Research Complex (TNRC) to identify promising new insecticide candidates for IR-4. The 2006 insecticide screening trial tested the performance of Emmamectin Benzoate (Proclaim 5SG®) and V-10170 on the grape berry moth (GBM), Endopiza viteana in grape. The resulting data suggested that Proclaim and V-10170 at their currently tested rates and timing may not be worthwhile candidates for future IR-4 submissions. Based on results of last year's screening trials we submitted an IR-4 "clearance request" for one new compound, novaluron (Rimon®) for prioritization at the 2006 IR-4 Food Use Workshop. At the workshop there was strong support among grape producing states to get Rimon registered with the EPA, but there was request by the registrant to delay the initiation of work one year in order for a new formulation with higher levels of plant-safety to be developed. Although this resulted in only a "B" priority for this year, we are confident to attain an "A" next year to lead to a future registration in grapes.
Development and Evaluation of Crown Gall-Free (Agrobacterium vitis) 'White Riesling', 'Chardonnay' and 'Cabernet franc' Grapevines
Thomas J. Zabadal
Goal: Winter injury and subsequent development of the crown gall disease is widely prevalent in eastern U.S. viticulture. The technology described above provides an opportunity to significantly reduce the impact of winter injury on cold tender cultivars. The economic impact could be enormous in terms of stable production of premium wine grapes in cool climates.zation at the 2006 IR-4 Food Use Workshop. At the workshop there was strong support among grape producing states to get Rimon registered with the EPA, but there was request by the registrant to delay the initiation of work one year in order for a new formulation with higher levels of plant-safety to be developed. Although this resulted in only a "B" priority for this year, we are confident to attain an "A" next year to lead to a future registration in grapes.
