Grape Research - Western Agricultural Research Center

grapes in a vineyard

Research Importance

MSU WARC is conducting research in cold-hardy grapes that are adapted to favorable sites in Montana to support the growing vineyard and winery industry in the state. There are currently 53 vineyards planted in Montana, with over 25,000 vines. WARC, in partnership with the Montana Wine and Grape Association, is studying pruning, control of canopy vigor, vine nutrition and irrigation practices in vineyards throughout the state, to help growers determine how these practices affect fruit chemistries (sugars and acids) for the optimal fruit quality and wine flavor.

The cold-hardy wine grape varieties that are grown in Montana and other USDA plant hardiness zone 4-6 areas are French-American hybrid grapevines, created by crossing French wine grapes (Vitis vinifera) that are only hardy to -5⁰ F with American native grapes, most commonly Vitis aestivalis (the Summer grape); Vitis riparia (the Riverbank grape), and Vitis rupestris, (the Sand grape). Breeding programs continue to improve hybrid grapevines, with active programs at Cornell University, the University of Minnesota and North Dakota State University that have created thousands of new varieties. In addition to cold tolerance, French-American hybrids are more resistant to common vineyard diseases like downy and powdery mildew, nematodes and phylloxera. French-American hybrids can produce quality wines when there’s sufficient heat during the growing season to ripen the grapes (~2000 growing degree days base 50⁰ F). Site selection is critical to ensure good ripening conditions and the most favorable areas in Montana include the Yellowstone River and Clark Fork of the Yellowstone valleys and warmer sites west of the continental divide.

Program Overview

Research Summary

MSU WARC current research vineyard was planted in 2014, with an additional planting in 2016. The varietals chosen at WARC are Marquette, Frontenac, Petite Pearl, Frontenac Gris, LaCrescent, and St.Pepin as wine grapes, with Somerset Seedless and Bluebell for table grapes. The 2016 planting included Crimson Pearl, Verona, Baltica, and three yet unnamed Tom Plocher varietals, TP B-3-40, TP 1-1-12 and TP 2-3-51 (http://www.petitepearlplus.com/). These vines are studied for their cold hardiness and winter survival rates, as well as their phenology, to monitor bud burst, fruit set, and harvest in this area of the state.

Results

The most popular red wine varieties currently planted in Montana include Marquette, Petite Pearl, Marechal Foch, and Frontenac, while the most widely planted white variety is St. Pepin, followed by Prairie Star. Some of the many other cold hardy varietals include Frontenac Gris, Crimson Pearl, St.Croix, Verona, LaCrescent, Leon Millot, Louise Swenson, Itasca, and Sabrevois. In our research vineyard, all varieties planted in 2014 have grown well. Among the red wine varieties, Frontenac has larger clusters (Table 1) and is very vigorous and productive (Table 2). Marquette has experienced higher mortality (Table 2, as seen in other vineyards in the state), but produces quality juice. Petite Pearl has lower sugar content and lower total acidity (TA, Table 2).

Our results also emphasize the balance between production and quality in grapes. In 2018, an average of 128 clusters per vine were left to ripen (more than twice the number compared to the year before). The increase in production was associated with a large increase in total acidity (Tables 2 and 3).

Table 1. Cluster and berry weights for grape varieties in trials planted in 2014 at WARC
Type	Variety	Cluster Wt (g)	Berry Wt (g)
Red	Frontenac	70.8	0.9
	Marquette	44.6	0.9
	Petite Pearl	44.7	0.9
Table	Bluebell	64.4	2.5
Table/White	Somerset Seedless	25	0.9
White	Frontenac Gris	73.3	0.9
	LaCrescent	52.9	1
	St. Pepin	66.3	1.8

Table 2. Performance of three cold-hardy, red wine grape varieties planted in 2014 over 3 years at WARC.
Variety	Year	% Fruiting	Harvest Date	Clusters per vine	Yield (lbs/plant)	Yield (lbs/acre)	Brix	pH	TA
Frontenac	2016	83	9/27	5	0.4	285	30.7	3.0	2.4
	2017	100	9/21	50	9.2	5995	23.8	3.0	1.9
	2018	100	10/3	149	19.3	12645	18.0	2.9	3.6
Marquette	2016	50	9/27	7	0.4	287	29.0	3.1	1.8
	2017	67	9/21	63	6.3	4157	23.7	3.0	1.7
	2018	67	10/3	126	12.1	7939	22.5	3.0	2.6
Petite Pearl	2016	92	9/27	7	0.6	384	21.9	3.1	1.3
	2017	92	9/29	72	7.6	4961	19.1	3.1	1.0
	2018	92	10/3	123	11.2	7368	17.0	3.0	2.4

All white wine varieties have been hardy and productive (Table 3). La Crescent and St. Pepin have had lower total acidity than Frontenac Gris when production is lower than 10 lbs/vine.

Table 3. Performance of three cold-hardy, white wine grape varieties planted in 2014 over 3 years at WARC.
Variety	Year	% Fruiting	Harvest Date	Clusters per Vine	Yield (lbs/plant)	Yield (lbs/acre)	Brix	pH	TA
Frontenac Gris	2016	67	9/27	3	0.3	185	29.9	3.0	2.3
	2017	75	9/21	41	7.3	4784	25.5	3.0	2.0
	2018	83	10/3	124	17.8	11658	18.4	3.0	3.2
La Crescent	2016	75	9/27	5	0.4	291	25.4	3.0	2.3
	2017	100	9/29	63	9.0	5867	24.4	3.0	1.8
	2018	100	10/3	143	13.0	8530	21.7	3.0	3.0
St. Pepin	2016	58	9/27	2	0.2	101	23.7	3.1	1.2
	2017	83	9/29	51	7.3	4812	21.3	3.1	1.2
	2018	83	10/3	103	15.2	9981	18.1	3.1	2.4

Both table grape varieties have grown well, although Bluebell experienced higher mortality rates in the first few years. Both are productive and have excellent flavor. Bluebell has large purple grapes (Table 1) with a Concord grape flavor. Somerset seedless has small, peach colored grapes with a flavor reminiscent of peach and raspberry that ripen 3 to 4 weeks before Bluebell (Table 4).

Table 4. Performance of two cold-hardy, table grape varieties planted in 2014 over 3 years at WARC.
Variety	Year	% Fruiting	Harvest Date	Clusters per Vine	Yield (lbs/plant)	Yield (lbs/acre)	Brix	pH	TA
Bluebell	2016	50	9/19	2	0.2	142	22.1	ND	ND
	2017	50	9/21	44	6.7	4381	21.3	3.1	0.9
	2018	86	10/3	76	10	6531	16.7	3.1	2.3
Somerset Seedless	2016	50	9/19	4	0.2	139	25.6	ND	ND
	2017	100	9/6	42	4.0	2651	23.3	3.2	1.0
	2018	100	9/9	161	9.0	5870	22.9	3.4	1.5

Conclusions

Quality table and wine grapes can be grown in warmer sites in Montana. MSU-WARC will continue to work with growers and winemakers to exploit the agro-tourism opportunities in the state.