As a resilient and sun-loving succulent, we Portulaca (often called Moss Rose or Purslane) are generally quite tough. However, even we can fall victim to certain pests and diseases that disrupt our vibrant blooms and fleshy foliage. Understanding these threats is key to keeping us healthy and flourishing in gardens across the USA.
Our succulent leaves and stems are a source of moisture and nutrients, making them a target for a few persistent insects. The most frequent unwelcome visitors are aphids. These tiny, soft-bodied insects, often green or black, cluster on our new growth and flower buds. They pierce our tissues to suck out sap, which can cause our leaves to curl, pucker, and yellow. More importantly, their feeding excretes a sticky substance called honeydew, which can lead to the growth of sooty mold, further inhibiting our photosynthesis.
Another significant pest is the spider mite. These are not insects but arachnids, and they are especially problematic in hot, dry conditions. They are minuscule and often go unnoticed until their damage is severe. They feed on individual plant cells, leaving behind tiny stippling marks on our leaves. A severe infestation will cover us in fine, silky webbing, causing our overall vigor to decline and our foliage to take on a bronzed or dusty appearance as we weaken.
Lastly, we can be susceptible to infestations of mealybugs and thrips. Mealybugs appear as small, white, cottony masses in the leaf axils and on stems, also sucking sap and excreting honeydew. Thrips are slender, tiny insects that rasp our petal and leaf surfaces, leading to distorted growth and silvery streaks or spots on our beautiful flowers.
The most common diseases that affect us are fungal and are almost always related to excessive moisture. Our succulent nature means we are highly drought-tolerant but intolerant of wet, poorly drained conditions. The primary fungal disease is stem and root rot, often caused by pathogens like *Pythium* or *Rhizoctonia*. This occurs when the soil remains soggy, either from overwatering or heavy rains coupled with poor drainage. The rot begins at the soil line, causing our stems to become soft, mushy, and blackened. The entire plant can quickly collapse and die if the roots are severely affected.
Another frequent issue is Botrytis blight, or gray mold. This fungus (*Botrytis cinerea*) thrives in cool, humid, and overcrowded conditions. It appears as a gray, fuzzy mold on our flowers, flower buds, and leaves. It typically attacks aging or damaged plant tissue first but can quickly spread to healthy parts, especially in periods of prolonged wet weather, causing blossoms to rot and foliage to develop large, soft, tan spots.
We can also suffer from powdery mildew, though it is less common than rot. This fungus presents as a white, powdery coating on our leaves and stems. Unlike Botrytis, it often develops in humid conditions with dry foliage. While it rarely kills us outright, it stresses us by interfering with photosynthesis, leading to stunted growth and reduced flowering.
