Understanding Sprouts on Grafted Avocado Trees: Characteristics and Management

Avocado trees are widely grown for their fruit and ornamental value. Grafting is often used in avocado cultivation to ensure the desired qualities are preserved. However, a common question that arises in avocado growers is what happens when a sprout emerges from the basal portion of a grafted tree. This article explores the characteristics of such sprouts and how to manage them.

Understanding Sprouts on Grafted Trees

Grafting in avocado trees is a technique where a bud or a branch from one variety (the cion) is attached to the rootstock of a different variety. The cion is chosen for its fruit quality, while the rootstock is usually chosen for its root-related qualities like disease resistance, soil adaptability, and vigor. If a sprout appears from below the graft union, it can pose a management challenge for growers.

Characteristics of Sprouts Below the Graft Union

If a sprout is growing from below the graft union, it will most likely have the characteristics of the rootstock. This is because the rootstock grows from the lower part of the trunk, and its genetic makeup determines the traits expressed by the tree below the graft level. In many cases, nurseries carefully select rootstocks for specific desirable traits, such as:

Soil adaptation and resilience to specific environmental conditions Drought resistance Increased vigor and faster growth Compatibility for dwarfing and reducing tree size

If the rootstock is a seedling, it might have limited predictability regarding its characteristics. However, nurseries usually aim for rootstocks with proven desirable traits. Ignoring these genetic traits can result in a tree that does not meet the desired management goals of the grower.

Managing Growth Reversions

Treating the sprout carefully is essential in maintaining the desired characteristics of the grafted tree. Here are some key points to consider:

Removing the Basal Sprout: It is generally recommended to remove the basal sprout as soon as it is noticed. If left, the reversion eventually spreads throughout the whole plant, resulting in the wild growth being dominant, which might be undesirable. This practice involves:

Identification of the sprout Pruning the sprout to prevent it from spreading to other parts of the tree Ensuring thorough removal to prevent regrowth

No Grafting: It is important to note that the sprout is not grafted and, therefore, will not become a grafted tree. The sprout originates from the rootstock, which means it lacks the cion's genetic material. Consequently, you cannot expect the sprout to regain the characteristics of the cion if it is pruned or removed.

Conclusion

Understanding the nature of sprouts on grafted avocado trees is crucial for maintaining and optimizing the performance of the tree. Proper management, including recognizing sprouts and removing them from below the graft union, is essential for ensuring that the tree retains the desired characteristics of the grafted cion. This approach not only preserves the quality of the fruits but also maintains the grower's intended management objectives.