MSU Extension Grapes

Introduction

Effective canopy management plays a critical role in grapevine cultivation, contributing to the overall health of the vineyard and the quality of the grapes produced. By implementing early season shoot thinning and positioning techniques, vineyard managers can strike a balance between vegetative growth and reproductive development, optimizing fruit yield and ripening potential. This article delves into the importance of canopy management, exploring key practices such as shoot density maintenance, the removal of weak and unwanted shoots, and the proper positioning of shoots within the trellis system.

By understanding and implementing these canopy management strategies, vineyard operators can mitigate challenges associated with excessive vine vigor, promote disease prevention and enhance the overall quality of their grape harvest. Early season canopy management plays a crucial role in Michigan vineyards, particularly due to the potential winter damages and their impact on pruning decisions. In our region, where harsh winters are common, grapevines are susceptible to winter cold injury. As a result, growers often use caution during winter pruning, leaving an excessive number of buds on the vines to compensate for potential losses. However, this conservative approach can lead to overcrowded canopies, reduced air circulation, increased disease pressure and diminished fruit quality.

The consequences of overcrowded canopies

Addressing challenges for vine health, grape quality and disease management

Overcrowded canopies pose significant challenges that can have detrimental effects on vine health, grape quality and disease management. Certain sites and grape varieties, particularly those with high vegetative vigor like Blaufrankisch, Cabernet Franc, Sauvignon Blanc, and several hybrids like Marquette, Chambourcin and Frontenac, are particularly susceptible to the development of dense canopies. Understanding the consequences of overcrowding is crucial for effective canopy management.

Here are the key challenges associated with overcrowded canopies:

Increased disease susceptibility. Dense canopies lack proper air circulation, resulting in high humidity and prolonged drying time after rainfall. This creates an ideal environment for diseases to thrive. Moreover, inadequate pesticide penetration further compounds the problem, making disease management more difficult.

Diminished grape quality. Shaded clusters within overcrowded canopies suffer from reduced varietal character, increased herbaceousness and delayed ripening. Adequate sunlight penetration into the canopy, especially reaching the clusters, is vital for producing uniformly ripened fruit with optimal levels of secondary compounds and varietal characteristics.

Pesticide application challenges. Crowded canopies limit the effectiveness of pesticide application, compromising disease management strategies. Controlling diseases like downy and powdery mildew, as well as late-season fruit rots such as Botrytis, becomes increasingly challenging.

Shoot thinning and positioning

Maintaining a delicate balance between vegetative growth and reproductive development is essential for successful grapevine cultivation. Early season shoot thinning and positioning play a crucial role in achieving this equilibrium. Here are key points to consider when implementing these practices:

Shoot density. The shoot density in VSP (vertical shoot positioned) and high cordon systems should be carefully managed, aiming for approximately three to five shoots per linear foot of trellis. However, it is important to consider factors such as cluster size and previous thinning levels. Adjustments to shoot density may be necessary to achieve optimal crop levels and ripening potential. It is worth noting that additional cluster dropping later in the season can help attain the desired crop level and enhance fruit ripening.

Removing weak and unwanted shoots. During the early stages, identify and thin out weak and unwanted primary and secondary shoots. These shoots can typically be easily snapped off by hand without causing any harm to the spur or cane. However, it is crucial to exercise caution and preserve secondary shoots in cases where the primary shoots have suffered cold damage. By safeguarding secondary shoots, future crops and spur development can be ensured.

Strategic shoot positioning. Timing is key when positioning the shoots within the catch wire. Carry out this task before the tendrils start attaching. Waiting too long increases the risk of shoot breakage during the positioning process, potentially harming vine health and fruit production. Each grape variety and vineyard location may have specific requirements and timing for shoot positioning, which should be determined based on individual vineyard conditions and growth patterns.

The importance of proper canopy management

Implementing effective canopy management practices in the vineyard offers a range of benefits that contribute to vine health, grape quality, and overall vineyard sustainability. Here are some key advantages of adhering to recommended shoot density and conducting timely canopy management:

Disease prevention. Maintaining the recommended shoot density and ensuring proper air circulation within the canopy is crucial for disease prevention. By reducing humidity levels and improving canopy drying after rainfall, a well-thinned canopy creates an unfavorable environment for disease development. This helps minimize the incidence of fungal diseases such as powdery mildew and downy mildew.

Efficient pest management. Proper canopy management allows for improved pesticide penetration and coverage. When the canopy is adequately thinned, sprays can reach the target areas more effectively, increasing the efficiency of pest management practices. This helps control harmful insects and pests that can damage both the vines and the grapes.

Reduced leaf removal. An optimally thinned canopy requires less leaf removal during vineyard maintenance. Excessive leaf removal can be time-consuming and labor-intensive. By achieving the desired shoot density early in the season, vineyard operators can minimize the need for excessive leaf removal, saving time and effort.

Enhanced fruit quality. One of the primary objectives of canopy management is to promote fruit quality. Proper shoot thinning allows for adequate sunlight penetration into the canopy and clusters. This exposure to sunlight helps in uniform fruit ripening, improving color development, flavor complexity and the accumulation of desirable secondary metabolites. A well-managed canopy also reduces the shading of leaves and clusters, mitigating the risk of herbaceous flavors and promoting varietal character.

Conclusion

Proper canopy management is a fundamental aspect of successful viticulture. By maintaining the recommended shoot density, conducting timely shoot thinning, and positioning shoots appropriately, vineyard operators can reap numerous benefits. These include disease prevention, efficient pest management, reduced leaf removal and enhanced fruit quality. Through careful attention to canopy management, vineyard managers can create an optimal environment for vine growth and grape development, leading to healthier vines, improved grape quality, and ultimately, the production of exceptional wines. By prioritizing canopy management practices, vineyards can achieve sustainable and thriving operations, ensuring the long-term success of their grapevine cultivation.