Petite pearl

Minneapolis, Minn. -- The development of cold-hardy grape varieties in breeding programs such as the University of Minnesota have made grapegrowing possible in the cold climates of the northern Midwest and New England. Now growers in those regions have a new red variety to add to the mix.

Tom Plocher, a Minnesota grape breeder, has just released Petite Pearl, a promising new cold-hardy red winegrape with a high degree of disease resistance and excellent wine potential. Unlike many of the northern red varieties, this grape has good tannins and low acids that make it one of the next generation of cold hardy hybrid grapes.

Petite Pearl is a 1996 cross between MN 1094 and ES 4-7-26. MN 1094 is a Minnesota hybrid with a complex parentage including vinifera, riparia and other species. ES 4-7-26 is an Elmer Swenson hybrid selected from seedlings of Swenson’s variety St. Croix.

The vine is moderately vigorous with an orderly trailing habit and little lateral growth, making it easy to manage in the vineyard. It is a late-ripening variety and in the Minneapolis area has a range of maturity extending from mid-September to early October. With a late spring break and bloom, there is less risk of damage from a late spring frost.

In the vineyard, Petite Pearl has outstanding cold hardiness and has survived several winters when low temperatures reached -32°F. Sharp overnight drops in temperature occur in most winters in Minnesota, and during a 50° drop in late December 2007, 3-year-old vines had little damage and 4-year-old vines none. Petite Pearl is highly disease resistant to downy mildew, powdery mildew and black rot. No bunch rot has been observed, even though Petite Pearl has compact clusters with small berries. However, minimal preventive spray protection is recommended. Thick skins give good cluster protection late in the season, and there have been no instances of berry split.

At harvest, sugar levels have averaged 24° Brix. Titratable acidity, low in comparison with other Minnesota red varieties, has averaged 0.8 and the pH has been 3.4. Depending on soil conditions, yields have ranged from 2 to 3 tons per acre.

Wine made from Petite Pearl has a dark garnet color and complexity in aroma and flavor. The soft mid-mouth tannins are a welcome departure from most other Minnesota reds with riparia in their background, which have lacked tannins and have required the use of oak to bring up the tannin levels. For this reason, Petite Pearl may be a valuable blending component in making those wines. Experimental wines made from Petite Pearl using D-254 yeast and French oak have been described as elegant.

Plocher summarized his opinion of Petite Pearl for Wines & Vines: “I think because of its cold hardiness and reliability in cold climates and its wine quality, it will have real promise in the Midwest, though not much north of the Twin Cities because of its late ripening, New England, New York and Québec. I look at Petite Pearl as one of the next generation of cold-hardy hybrid grapes.”

Three nurseries are carrying Petite Pearl:
• Bevens Creek Vineyard and Nursery, 9350 Foxford Road, Chanhassen, Minn. 55317. Contact Dell Schott, (952) 212-0523; e-mail: dellsss@yahoo.com

• Northeastern Vine Supply, 2494 Route 140, Poultney, Vt. 05764. Contact Andy Farmer, (802) 287-9311; www.nevinesupply.com

• A&M Viticulture, St. Paul d’Abbotsford, Québec. Contact Alain or Mariette Breault, (450) 379-5302; e-mail: coquine@endirect.qc.ca

Tom Plocher lives in Hugo, Minnesota, and may be contacted by e-mail at tplocher@msn.com.