Purple coral pea (Hardenbergia violacea) is a decorative, flowering plant that grows as a sprawling shrub or climbing vine. It is native to the coastal regions of eastern Australia, but is also cultivated in the United States and Europe. Purple coral pea is relatively hardy and tolerates various soil conditions, including both shady and exposed locations. Several factors, including pests and diseases, damage this plant's leaves, causing them to wilt and die.
Various herbivores feed on purple coral pea's foliage. They may completely consume some leaves or only eat part, leaving the rest of the leaf to die. Extensive damage to a single plant may cause additional leaves and stems to wither. According to the Tasmanian Department of Primary Industries, Parks, Water and Environment, grazing by animals, such as deer, sheep and rabbits, threaten the survival of the native purple coral pea population in Tasmania. Protect domestic plantings with cages or fences limiting damage from wildlife.
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Purple coral peas are plagued by relatively few insect pests, but occasionally an infestation attacks the plant's leaves and other green growth. According to the Royal Botanical Gardens and Domain Trust, mealybugs, scales and various caterpillar species consume the foliage. Scales are serious pests that travel in large numbers, often in the hundreds or thousands. They cover the surface of green growth, such as leaves and stems, feeding on sap. Mealybugs attack the roots, leaves and flowers. According to the University of Florida, mealybug infestation symptoms include discoloration, wilting and distorted growth of leaves.
Fungal diseases harm the purple coral pea vines' leaves. Elsinoe leaf spot, caused by the Elsinoe hardengergiae fungus, targets purple coral pea and its close relatives. According to the Victoria Department of Primary Industries, this fungal ailment is a common problem for nursery plants, particularly during autumn. The fungus causes discolored patches on leaves and stems. Infected tissue eventually rots away, leaving tears across the affected foliage's surface. Powdery mildew, a prolific fungus that grows in white colonies, also damages leaves and stems. Pruning stems and leaves affected by a fungal infection and removing all debris at the end of the year prevents the fungus from surviving through the winter.
A soil chemistry imbalance or other adverse environmental conditions can kill the leaves. They are not drought tolerant, so long periods of low moisture stress the plant and causes leaves to become desiccated and eventually die. On the Australian continent, several weeds, such as African boxthorn (Lycium ferocissimum) and boneseed (Chrysanthemoides monilifera), compete with purple coral pea. Purple coral pea tolerates a range of soil types, but prefers slightly acidic soil with a pH between 5.5 and 6.0. Severe pH levels cripple plants by inhibiting the uptake of nutrients from the soil, so balancing the pH with limestone or the appropriate fertilizer may be necessary. Heavy, saturated soil is also a problem for purple coral pea. Excess water damages the plant's roots and fosters fungal growth.
- Tasmania Department of Primary Industries, Parks, Water and Environment; Hardenbergia Violacea; October 2005
- The Royal Botanic Gardens and Domain Trust: Growing Hardenbergia Violacea Flat White and Carpet Royale
- Victoria Department of Primary Industries; Elsinoe Leafspot of Hardenbergia; Ian Pascoe et al.; September 1994