41 B Millardet et de Grasset
Name of vine variety in France (and common name)
41 B Millardet et de Grasset (41 B MGt)
Breeder and year of obtention
Alexis Millardet and Charles de Grasset, 1882
Genetic origin
This variety was derived from the crossbreeding of Vitis vinifera cv. Chasselas B and Vitis berlandieri.
Evolution of areas under rootstock nurseries
1945 1955 1965 1975 1985 1995 2005 2015
Rank 3 3 2 2 2 4 5 6
ha 152 504 634 745 379 229 196 133
Estimated surface area of French vineyards grafted with this rootstock and the main areas of use
80 000 ha. Champagne, Bourgogne Franche-Comté, Midi-Pyrénées, Val de Loire, Aquitaine, Charentes,
Provence-Alpes-Côte d’Azur, Languedoc-Roussillon, Rhône-Alpes
Ampelographic description
Identification signs include:
- the tipe of the young shoot which is open has a very dense coat of flat-lying hairs and anthocyanin pigmentation on the edges.
- bronze colored young leaves,
- the shoot has a very ribbed contour with a circular section or slightly elliptical with an absence of upright and flat-lying hairs,  
- fairly developed tendrils,
- orbicular to wedge shaped adult leaves, whole with an almost completely upturned leaf blade but revolute on the edges,  a U-shaped petiolar or not very open lyra shape limited by the vein near the petiolar point, short teeth with straight sides. 
- female flowers,
- the berries are small, round-shaped ad the skin in bluish black,
- the vine shoots have a fairly large diameter with brownish gray internodes and darker nodes.
Genetic profile
Allel 1 133 223 231 254 194 256 254 241 239
Allel 2 141 225 239 255 194 260 255 267 255
Resistance to soil parasites
The degree of tolerance of 41 B MGt to radicicolae phylloxera is moderate to high. It is also sensitive to the nematodes Meloidogyne incognita, Meloidogyne arenaria and Meloidogyne hapla and would appear sensitive to Agrobacterium vitis.
Adapt to environment
41 B MGt is characterized by its adaptation to limestone soils and its resistance to chlorosis. It resists up to 60% of total limestone, 40% of active limestone and a CPI of 60. It likewise absorbs magensium in the soil well. 41 B MGt is however sensitive to temporary excess humidity conditions in the spring and its reistance to drought is moderate. It would appear not very adapted to soils which are too compact.
Interaction with grafts and production objectives
The vigor transferred by 41 B MGt to the grafts is moderate to strong.It generally presents good affinity with grafts even if problems have been noted with blending with Merlot N and Pinot noir N which is however grafted in large numbers with this root stock. The beginning plant development is rather slow. 41 B MGt promotes grape cluster compactness. It also tends to dealy the vegetative cycle of grafts. Compared to other root stocks, the products obtained are always less rich in sugar and slightly more acidic.
Aptitudes for plant propagation
The length and diameter of the internodes are moderate to large and wood production (15 000 to 50 000 m/ha) is low to moderate with sometimes a certain proportion of dry wood. In nursery stocks, 41 B MGt is both sensitive to hydric stress and to excess humidity in the soil. It can also be affected by wilting of the vine trunks. 41 B MGt wood lignifies easily. Once harvested, they must be stored correctly and be sufficiently rehydrated before using. Debudding and cutting is fairly easy. The propagation by cuttings capacity of 41 B MGt is low to moderate with occasionally the onset of necrosis at the bottom of the plants but it displays good aptitude for grafting. Special attention (duration, hormoning) must be paid during the stratification phase in order to avoid large calluses.
Resistance to aerial parasites
41 B MGt presents a high degree of tolerance to gallicolae phylloxera  but is sensitive to downy mildew.
Clonal selection in France
The 16 approved 41 B MGt clones carry the numbers: 80, 86, 87, 88, 153, 172, 193, 194, 195, 210, 212, 231, 232, 233, 238 and 1177.