The Concept of Grafting in Avocados
Grafting is a horticultural technique that involves joining two plants together so they grow as one. In the world of avocados, this practice is common and can yield impressive results. The “scion,” or the part of the plant that bears the fruit, is attached to a “rootstock,” the root system that will support the entire tree.
Importance of Rootstock Selection
Choosing the right rootstock is not just a trivial gardening decision; it’s a critical factor that can make or break your avocado tree’s health and productivity. The rootstock influences:
- Tree Health: A strong rootstock provides better nutrient uptake.
- Fruit Yield: Certain rootstocks can increase the amount of fruit your tree produces.
- Disease Resistance: Some rootstocks offer resistance to devastating diseases like Phytophthora root rot (PRR).
Pull Quote: “The rootstock is the foundation of your avocado tree. Choose wisely.”
Variance in Performance
Not all rootstocks are created equal. Their performance can vary significantly depending on:
- Soil Conditions: Some rootstocks thrive in sandy soils, while others prefer clay.
- Climatic Conditions: Cold-hardy rootstocks are different from those suited for tropical climates.
This article aims to provide a comprehensive guide on the commonly used rootstocks, their adaptability to various environmental conditions, recent advances in rootstock development, and practical considerations for growers. Whether you are a commercial grower or a home gardener, you’ll find valuable insights to help you make an informed decision on rootstock selection for grafting avocados.
Click here for more information on how to graft your own avocado tree
Commonly Used Rootstocks for Avocado Trees
When it comes to grafting avocados, rootstock selection is key. There are numerous options, each with its unique set of advantages and disadvantages. Below are some of the most commonly used rootstocks in the avocado industry and among home gardeners.
A. Zutano Seedling
Popularity Among Home Gardeners
Zutano is a favorite among home gardeners for a simple reason: it’s easy to come by. Many novice growers start their avocado journey with a Zutano seedling.
Accessibility and Affordability
One of the significant advantages of Zutano is that it’s generally affordable and accessible. You can often find Zutano seedlings at local nurseries or even start one from a seed.
Pull Quote: “Zutano is the beginner’s friend in the world of avocado rootstocks.”
B. Dusa
Origins and Recognition
Originally from South Africa, Dusa has gained considerable recognition, especially in California, for its resilience and performance.
Tolerance to Root Rot
Dusa is highly tolerant to Phytophthora root rot, a common disease that plagues avocado trees.
Soil Preference
This rootstock performs exceptionally well in non-saturated soil conditions, making it versatile for different types of terrains.
C. Duke 7 and Toro Canyon
Notable Appearance
Both Duke 7 and Toro Canyon stand out for their robust structure and notable appearance, often characterized by vigorous growth.
Vigorous Growth in Trials
In various trials, these rootstocks have shown a propensity for vigorous growth, making them a compelling choice for those looking to maximize tree size and yield.
D. Hass
Commonality as a Rootstock
Hass is frequently used as a rootstock, and it’s not just because of its name recognition as a popular fruit variety.
Reasons for Being Chosen
Many choose Hass due to its generally good all-around performance, although it may not excel in any one particular area like disease resistance or yield.
Adaptability to Environmental Conditions
In the complex world of avocado growing, environmental conditions play a pivotal role. Not every rootstock can thrive in all conditions, which makes the choice of rootstock even more critical. Let’s delve into how different rootstocks adapt to varying environmental factors such as cold, salinity, and disease resistance.
A. Cold Tolerance
Mexican Race Avocados and Other Varieties
When the mercury drops, certain avocado rootstocks stand up to the chill better than others. Mexican race avocados, along with Bacon seeds, Mexicola seeds, and Fuerte, are known for their cold-hardiness.
Toro Canyon and Duke 7
Both Toro Canyon and Duke 7 have also received high marks for cold tolerance in various studies. If you live in a region with colder winters, these could be your go-to options.
Pull Quote: “Cold tolerance is not just a luxury; it’s a necessity in certain climates.”
B. Salinity Tolerance
Dusa (Merensky II) and Toro Canyon
In areas with saline irrigation water, Dusa (also known as Merensky II) and Toro Canyon are often the preferred choices. They have shown resilience in conditions where salt levels in the soil are elevated.
Steddom and Velvick
Other notable mentions for good salt tolerance include Steddom and Velvick rootstocks. These can be alternative options if Dusa or Toro Canyon are not available.
C. Disease Resistance
Dusa, Duke 7, and Toro Canyon
Phytophthora cinnamomi, commonly known as avocado root rot, is a formidable enemy for avocado growers. Dusa, Duke 7, and Toro Canyon are widely recognized for their resistance to this disease.
New Entrants: Zentmyer, Steddom, and Uzi
Recent developments have introduced new rootstocks specifically designed for Phytophthora root rot (PRR) tolerance. These include Zentmyer, Steddom, and Uzi, and they offer a new line of defense against this devastating disease.
Understanding how these rootstocks fare under various environmental conditions can help you make an educated choice. From the frosty challenges of cold climates to the salty soils of certain regions, selecting the right rootstock can be the difference between a struggling tree and a thriving one.
Advances in Rootstock Development
Advancements in rootstock development are a game-changer in the field of avocado cultivation. By leveraging scientific research and biotechnology, new types of rootstocks are being developed to address various challenges that growers face. Here, we’ll explore two significant areas of advancement: clonal rootstocks and the development of Phytophthora root rot (PRR)-tolerant rootstocks.
A. Clonal Rootstocks
Demonstrated Resistances
Clonal rootstocks are not grown from seeds but are instead produced through grafting. One of their significant advantages is their demonstrated resistance to diseases, particularly when compared to seed-grown rootstocks.
Consistency is Key
Another benefit of clonal rootstocks is their consistency. Because they are genetically identical to the parent plant, there are fewer surprises when it comes to performance.
Pull Quote: “With clonal rootstocks, what you see is generally what you get: consistent performance and resistance.”
B. Development of PRR-tolerant Rootstocks
The Introduction of New Varieties
The University of California, Riverside, has been at the forefront of developing PRR-tolerant rootstocks. Notable among these are Zentmyer, Steddom, and Uzi.
The Long-term Objective
While these new rootstocks offer improved tolerance to PRR, the ultimate goal remains elusive: finding a rootstock that is truly resistant to this devastating disease. It’s an area of ongoing research, and future developments are eagerly awaited.
Practical Considerations
While scientific advancements and adaptability to environmental conditions are essential, practical considerations are equally crucial. From local availability to individual grower preferences and commercial propagation, these factors significantly influence the choice of rootstock.
A. Local Availability
Availability of Certain Rootstocks
Not all rootstocks are widely available. For instance, Velvick rootstocks might be hard to come by depending on your location.
Impact on Choices
Limited availability often forces growers to opt for what’s accessible rather than what’s ideally suited for their specific needs.
Pull Quote: “Sometimes, the best rootstock is the one you can actually get.”
B. Grower’s Preference
Shared Experiences
Growers often turn to online forums and local communities to share their experiences and preferences. These first-hand accounts can provide valuable insights that scientific data alone may not capture.
Role of Preferences
Personal preferences based on these shared experiences can sometimes outweigh scientific recommendations, especially for home gardeners.
C. Commercial Propagation
Licensing and Propagation
Newly developed rootstocks often come with licensing agreements that can limit their availability. These rootstocks are usually propagated on a commercial scale and are subject to regional distribution restrictions.
Market Availability
The commercial propagation of new rootstocks ensures they become more widely available over time, but it can take a while before they are easily accessible to the average grower.
Practical considerations can be the deciding factor in your choice of rootstock. Whether it’s the availability of specific types in your area, personal preferences influenced by community insights, or the commercial propagation of new varieties, these practical aspects deserve your attention.
Growing Avocados at Home: A Rootstock Guide
If you’re a home gardener looking to grow avocados, you may wonder if all the talk about rootstocks is relevant to you. The answer is a resounding yes. Picking the right rootstock can make a world of difference in your backyard or even in your indoor gardening endeavors. Here are some key considerations.
A. Seed-Grown vs. Grafted Trees
Seed-Grown Trees
Growing an avocado tree from a seed might seem like the simplest route, but there are downsides. These trees take longer to produce fruit, and there’s no guarantee of the quality of the fruit.
Grafted Trees
On the other hand, grafted trees, which involve attaching a scion to a rootstock, offer quicker fruit production and known fruit quality. The rootstock plays a vital role in this.
Pull Quote: “For quicker fruiting and disease resistance, consider grafted avocado trees.”
B. Popular Rootstocks for Home Gardening
As discussed earlier, Zutano is a popular choice among home gardeners due to its affordability and accessibility. Duke 7 is also a strong candidate if you’re looking for something more robust and tolerant to different conditions.
C. Local Climate and Disease Concerns
Your local climate should influence your choice of rootstock. If you’re in a colder region, consider rootstocks known for their cold tolerance like Duke 7 and Toro Canyon.
Similarly, if your local area is known for certain diseases like root rot, opt for a rootstock with high disease resistance like Dusa.
D. Starting Small
If you’re new to avocado growing, you might want to start with a mini-tree or even try container gardening. In such cases, rootstocks like Duke 7 are often recommended for their moderate growth habits.
Conclusion
Choosing the right rootstock for grafting avocados is not a decision to be taken lightly. From the commonly used options like Zutano and Dusa to considerations of adaptability to different environmental conditions such as cold and salinity, each rootstock brings its own set of advantages and challenges.
Pull Quote: “Your choice of rootstock is the cornerstone on which your avocado tree’s future rests.”
It’s not just about what’s popular or scientifically recommended; practical considerations like local availability and personal preferences also play a crucial role. Advancements in rootstock development, such as clonal rootstocks and disease-resistant varieties, offer promising avenues for improving yield and resilience.
As the search for the ideal rootstock continues, sharing knowledge and experiences within the avocado growing community becomes ever more vital. The field is ripe for continued research and community collaboration to help both commercial growers and home gardeners make informed decisions for a fruitful future.
In summary, the right rootstock can significantly impact your avocado tree’s health, fruit yield, and resistance to diseases and environmental stressors. Choose wisely, and don’t hesitate to tap into the collective wisdom of the avocado growing community.
References
https://gregalder.com/yardposts/avocado-rootstocks-what-do-they-matter/
https://www.viverosbrokaw.com/products/avocado/avocado-rootstocks/
https://phys.org/news/2012-04-avocado-rootstocks-high-performing-disease-tolerant.html