Grevillea plants, with their stunning and intricate flowers, are generally resilient, but like all members of the plant kingdom, we can fall victim to a few persistent pests. These invaders disrupt our vital processes, sapping our strength and diminishing our beauty. Understanding these adversaries from our perspective is key to maintaining our health.
Our succulent new growth and the undersides of our leaves are prime targets for these tiny vampires. Aphids cluster on our stems, scale insects attach themselves like immobile bumps to our branches, and spider mites weave fine webs while piercing our cells. Their feeding drains our precious sap, which is rich in nutrients we've worked hard to produce. This leads to distorted, stunted, or yellowing leaves and a general decline in our vigor. The honeydew they excrete is an even greater insult, as it attracts sooty mold fungus, which coats our leaves and blocks the sunlight we need for photosynthesis.
These pests are particularly frustrating. The adult insects lay eggs on our leaves, and the hatched larvae burrow inside, feeding on the internal tissue between the leaf surfaces. From our perspective, we can feel these serpentine tunnels (mines) being carved out, which not only damages the affected leaf but also creates unsightly trails that spoil our appearance. While a minor infestation is something we can often tolerate, a severe attack can cause significant leaf drop, weakening us and making us more susceptible to other stresses.
Perhaps the most alarming pests are those we cannot see. Larvae of various beetles, such as curl grubs, inhabit the soil around our root system. They feed directly on our delicate roots, which are our primary means of absorbing water and nutrients from the soil. From our point of view, this is a direct attack on our very foundation. The above-ground symptoms are often vague but serious: unexplained wilting, a failure to thrive despite adequate water and sun, and yellowing or bronzing of our foliage. The damage is done in secret, often only discovered when it is already advanced.
For sap-sucking pests, a strong jet of water can physically dislodge many of them. For more persistent issues, horticultural oils or insecticidal soaps are effective as they suffocate the pests without leaving harmful residues that could also affect our pollinators. Introducing beneficial insects, like ladybugs for aphids, is a strategy we greatly appreciate as it restores the natural balance. For leaf miners, the best approach is often to simply remove and destroy the affected leaves, cutting off the pest's life cycle. Regarding root feeders, beneficial nematodes applied to the soil can seek out and destroy the grubs without harming our roots or the surrounding ecosystem. In all cases, ensuring we are planted in well-draining soil and receive appropriate water and sunlight is the best defense, as a strong, healthy Grevillea is far more capable of resisting and recovering from pest attacks.
