Black Spot and Powdery Mildew on a Golden Shrimp Plant

The golden shrimp plant (Pachystachys lutea) is a shrub with dark green leaves and bright yellow bracts. This tropical plant is generally easy to grow but occasionally experiences various foliar diseases.

Black Spot

Black spot (Diplocarpon rosae) is a fungal disease that causes black spots to appear on the upper section of golden shrimp plant foliage and on its stems. The spot margins are often yellow, and the leaves eventually drop. The University of California Statewide Integrated Pest Management Program suggests treating black spot with neem oil or a homemade spray made of 4 teaspoons baking soda mixed with 1 gallon water and a 1 percent solution of a narrow-range horticultural oil.

Powdery Mildew

Powdery mildew is a fungal disease that causes a white powder to form on the leaf surfaces of golden shrimp plant. Infestations can be eradicated with fine horticultural oil, neem oil or jojoba oil. There are also some fungicides designed to eliminate the condition.

Prevention/Solution

Preventing black spot on golden shrimp plants requires keeping the foliage dry and providing good air circulation around plants. Avoid powdery mildew by placing golden shrimp plants in a part-sun location, rather than a shady site, and spraying them with a preventative fungicide.

References

• "Pachystachys Lutea Golden Shrimp Plant"; Edward F. Gilman, et al.; 2009
• University of California Statewide Integrated Pest Management Program: Black Spot --- Diplocarpon Rosae
• University of California Statewide Integrated Pest Management Program: Powdery Mildew on Ornamentals

Resources

• University of Connecticut: Pachystachys Lutea