The 41 B Millardet et de Grasset rootstock, more commonly known as 41 B MGt, represents a historic and still highly relevant solution to viticultural challenges, particularly adaptation to limestone-rich soils. Resulting from a judicious cross, it established itself as a cornerstone of post-phylloxera reconstruction and continues to offer significant advantages for modern viticulture, especially in regions with limestone-dominated terroirs.

Origin and development of an exceptional rootstock

The 41 B MGt rootstock is the result of research conducted by Millardet and de Grasset, two iconic figures in French viticulture following the phylloxera crisis. Created at a time when the survival of the vineyard was at stake, it is the result of a cross between Vitis vinifera Chasselas and Vitis berlandieri. This combination aimed to unite the good grafting affinity of Chasselas with the limestone and phylloxera resistance of Berlandieri. Its development was part of a major effort to find long-term solutions against the devastating pest that was ravaging European vineyards.

Rootstock profile

The 420 A MGt rootstock (420 A Millardet et de Grasset)ot>

Adaptation and performance in limestone soils

41 B MGt is particularly valued for its very high tolerance to active limestone, capable of adapting to soils containing up to 60% active limestone with a Chlorosis Power Index (CPI/IPC) of 40. This characteristic makes it indispensable in wine regions with highly calcareous subsoils. It also exhibits very good drought resistance, which is a valuable asset in the context of increasingly hot summers. On the other hand, it shows moderate tolerance to wetness and compact soils, being susceptible to root asphyxiation under such conditions. Its ability to thrive in gravelly or clay soils depends on their drainage.

Behaviour and impact on the scion

This rootstock confers medium to high vigour to the scion, promoting sound vegetative growth. It has the distinctive trait of advancing grape ripening, which can be an advantage for certain varieties and in specific climatic conditions. In terms of water and nitrogen uptake, 41 B MGt maintains balance, thereby contributing to the quality of the grapes and, ultimately, the wines. Its impact on yield is generally well-balanced, avoiding excess, which helps maintain optimal quality.

Graft affinity and vineyard management

41 B MGt exhibits good affinity with most Bordeaux grape varieties, ensuring a solid and durable union. For optimal management, moderate planting densities are recommended; its vigour accommodates various pruning systems, although moderate pruning is often favoured to control yields. Particular attention should be paid to irrigation on very dry and shallow soils, despite its natural drought tolerance.

Vulnerabilities and points of vigilance

Although high-performing, 41 B MGt is not without vulnerabilities. Its primary weakness lies in its sensitivity to excess moisture and waterlogged soils. Despite its strong tolerance to limestone, iron chlorosis can appear in extreme cases or under nutritional imbalances. It also shows moderate susceptibility to nematodes and fanleaf degeneration (court-noué), occasionally requiring heightened vigilance in affected parcels.

41 B MGt in the face of climate challenges

With ongoing climate change, the drought resistance of 41 B MGt is a major asset for Bordeaux viticulture. Its ability to advance scion ripening can be advantageous, allowing harvests before late-season heat peaks. These traits make it a relevant choice for winegrowers seeking to adapt their vineyards to changing climate conditions while preserving high production quality.

Use of 41 B MGt at Château Cazebonne

At Château Cazebonne, we do not use this rootstock because limestone is scarce on our estate.
We are committed to replanting forgotten grape varieties and exploring viticultural solutions suited to future challenges. In this context, we might consider robust rootstocks such as the 140 Ru (140 Ruggeri) rootstock, or the 5 BB (Kober 5 BB) rootstock. Alternatively, the SO 4 (Sélection Oppenheim 4) rootstock also offers interesting characteristics. This work is made possible thanks to the support of wine enthusiasts who discover our cuvées and choose to buy our wines online. To learn more about the fascinating history of the grape varieties that shaped our region, feel free to download our book "Bordeaux, une histoire de cépages" and test your knowledge with our wine quizzes. You can also read our article on the 101-14 MGt (Millardet et de Grasset) rootstock.