Green With Envy: Sabrina Hahn's Weekly Gardening Q&A Session
Every Saturday, gardening expert Sabrina Hahn delves into the most pressing horticultural challenges faced by West Australian gardeners. In her latest column, she provides detailed solutions for issues ranging from invasive weeds to problematic fruit trees, drawing on her extensive experience and knowledge.
Unwelcome Weed: A Dangerous Intruder in the Garden
Emil Pilkiw from Beckenham discovered a small tree, approximately 3 meters tall, with white flowers and large green pods featuring soft spikes. Sabrina Hahn identified this plant as the swan plant, also known as narrowleaf cottonbush (Gomphocarpus fruticosus).
This species is classified as a terrible weed that has spread extensively across the Swan Coastal Plain and Darling Range, from Perth to Busselton. The plant produces numerous seeds that germinate easily, allowing it to dominate areas rapidly. Importantly, it is poisonous to livestock, posing a significant risk. Hahn advises immediate removal to prevent further spread and protect local ecosystems.
Nut Good News: Saving a Rotting Macadamia Tree
Ben Giustiniano from Menora sought help for a macadamia tree transplanted from his late grandfather's home about five years ago. The tree shows signs of rotting at the base, despite producing nuts each summer that are picked green, as they rarely fall to the ground in time for consumption.
Sabrina Hahn diagnosed the tree with rot that has damaged half of the cambium layer, but noted it is beginning to heal and callus over. Her recommendations include:
- Pruning the tree by one-third to reduce stress.
- Using grafting tape to wrap the trunk entirely, protecting it from further infection.
- Removing side shoots to prevent them from developing.
- Applying compost and biochar around the base, along with a wetting agent, and watering thoroughly.
- Adding a layer of lupin compost, kept well away from the trunk, to promote health and healing.
These steps aim to support the tree's recovery and ensure it continues to thrive.
Cumbersome Fruit: The Mystery of Seedless Avocados
Paul Fuller from Mt Barker reported an issue with his Fuerte avocado tree, which produces small, gherkin-shaped fruit up to 7cm long with no seeds, unlike his Hass avocado trees that yield normal-sized fruit. All trees receive similar fertilizing, water, and soil conditions.
Sabrina Hahn explained that this phenomenon is a known trait of Fuerte avocados. The cucumber-like fruits, called 'cukes,' occur when flowers are not fully pollinated but still develop into seedless fruits. While the exact reason for this is not fully understood, the fruits remain edible and offer the unique benefit of being seedless. Hahn reassured Fuller that this is a natural occurrence and not a cause for concern regarding the tree's overall health.
How to Submit Your Gardening Questions
Readers are encouraged to submit their own gardening questions to the Green With Envy column, published in Saturday's edition of The West Australian. To participate, write to Ask Sabrina, GPO Box D162, Perth, 6001, or email home@wanews.com.au. Please include your full name and suburb. Due to the high volume of inquiries, not all questions can be answered, but Sabrina Hahn continues to provide valuable insights for the gardening community.
