As a Protea plant, my kind has traveled far from our native South African fynbos to grace gardens and nurseries across the United States. While we are celebrated for our bold, architectural beauty, this new environment presents unique challenges. From my perspective, my survival hinges on robust health, but certain pests and diseases can threaten my vitality. Here is a detailed account of the primary adversaries I face.
My tough, leathery leaves are a defense mechanism, but they are no match for insects that pierce and suck. Aphids are a common nuisance. They cluster on my tender new growth and flower buds, sucking the sugary sap I have worked so hard to produce. This weakens me, causing leaves to curl and distort. More alarmingly, aphids excrete a sticky substance called honeydew, which attracts sooty mold—a black, fungal growth that coats my leaves, blocking sunlight and further impeding my photosynthesis. Scale insects are another stealthy threat. They attach themselves to my stems and the undersides of leaves like small, immobile bumps, draining my fluids slowly and often going unnoticed until I show signs of yellowing and stunted growth.
Perhaps the greatest danger to me is not what happens above ground, but what occurs below. I am a plant of well-drained, acidic, and relatively poor soils. My roots are adapted to seek moisture in gritty, sandy conditions and are highly susceptible to rot if left sitting in water. The primary culprits are fungi from the Phytophthora and Pythium genera. In overly moist, compacted, or poorly draining soil, these pathogens attack my root system, causing it to turn brown, mushy, and ineffective. From my perspective, this feels like a slow suffocation and starvation. My leaves begin to wilt, yellow, and die back, even when the soil seems damp. Unfortunately, by the time these above-ground symptoms are visible, the damage to my root system is often severe and frequently fatal.
Humidity is my enemy. In regions of the US with humid summers, fungal pathogens thrive. Gray mold, or Botrytis blight, caused by the fungus Botrytis cinerea, is a significant concern, especially during cool, wet periods. It appears as a fuzzy gray mold on my flower heads and leaves, causing buds to rot before they open and spoiling the spectacular blooms for which I am grown. Leaf spot diseases, caused by various fungi, also manifest as unsightly brown or black spots on my foliage. These spots can coalesce, causing leaves to yellow and drop prematurely, which reduces my overall energy-capturing capacity and weakens me over time.
Some pests cause direct, physical destruction. Protea borers are the larvae of certain moths that tunnel into my stems. This activity disrupts the vital flow of water and nutrients, causing entire branches to wilt and die back suddenly. The entry holes also provide an opening for secondary fungal infections. Additionally, various caterpillars find my foliage palatable. They chew irregular holes in my leaves, and while a small amount of damage is tolerable, a severe infestation can defoliate me, leaving me unable to photosynthesize effectively and sapping my strength for future growth and flowering.
