Choosing the right citrus rootstock for optimal growth and yield
Citrus rootstocks serve two essential functions. Firstly, they help overcome environmental limitations related to soil quality, water issues and climate conditions. Secondly, they improve the fruit’s marketability by affecting size, yield and internal quality. The longevity of a citrus orchard, typically 25 to 40 years, largely depends on choosing the right rootstock at the outset. If a rootstock proves unsatisfactory, the trees can be top-worked, however, this process delays production by at least two years.
Factors to consider when choosing a rootstock
- Climate analysis: Understanding the local climate is essential for choosing rootstocks with the right cold and drought tolerance
- Water quality and quantity: Conducting a water analysis ensures that rootstocks with appropriate tolerance to salinity and irrigation conditions are selected
- Soil classification and analysis: Soil type, pH and drainage influence rootstock performance. For example, calcareous or clay-heavy soils may not suit all rootstocks
- Disease presence: Nematodes and Phytophthora can devastate crops, so selecting disease-tolerant rootstocks is crucial
- Compatibility with scion cultivars: Some rootstock-scion combinations are incompatible, leading to stunted growth or other issues
5 popular citrus rootstocks in South Africa
South African growers primarily use five rootstocks, each with distinct strengths and weaknesses:
- Carrizo Citrange
- Vigour: Moderate growth and productivity
- Tolerance: Poor tolerance to high-pH soils and calcareous conditions but does well in moderate soils
- Fruit characteristics: Produces medium-sized, high-quality fruit but prone to inducing creasing in scions
- Swingle Citrumelo
- Vigour: High initial growth rate, second only to Rough Lemon
- Tolerance: Excellent resistance to nematodes and Phytophthora. Tolerant to poor drainage and drought but sensitive to high-pH soils
- Fruit characteristics: Produces fruit like Carrizo, with good yield and quality but lower acidity
- X639 Citrandarin
- Vigour: Moderate growth, slightly less than Swingle and Carrizo
- Tolerance: Best suited for high-pH soils and calcareous conditions. Excellent cold and frost tolerance
- Fruit characteristics: Slightly lower yields than Swingle and Carrizo but good internal fruit quality
- C-35 Citrange
- Vigour: Semi-dwarfing, with a growth slowdown after six years, leading to a final size 15 to 25% smaller than Carrizo
- Tolerance: High resistance to nematodes and Phytophthora but struggles in high-pH soils
- Fruit characteristics: Produces the highest Brix (sugar content) and acid percentages, making it ideal for sweeter fruit production
- Rough Lemon
- Vigour: The most vigorous rootstock, leading to the largest trees
- Tolerance: Poor cold tolerance but recovers quickly from frost. Performs best in deep, sandy soils and has some resistance to creasing
- Fruit characteristics: Produces large fruit with thick rinds and low juice content, making it less ideal for high-quality fruit markets
Conclusion
Choosing the correct citrus rootstock is vital for the success of your orchard. By considering factors such as soil quality, climate and scion compatibility, one can select a rootstock that ensures strong growth, high yields and superior fruit quality. Make the right decision today and enjoy a thriving citrus orchard for decades to come.
Contact us for more information and to order your rootstocks and trees: info@duroi.co.za
