Fungal diseases and pests pose a significant threat to your privet plants (Ligustrum species), potentially causing severe cosmetic damage and decline. Though prized and widely used in the home landscape as border plants and hedges, your privets are not immune to fungal pathogens. Privets will not consistently perform once infected, but with appropriate care and observation, you can avoid problems and maintain a healthy home garden.
Gray mold is a fungal disease of privet plants, caused by the fungal pathogen Botrytis cinerea, according to the University of Illinois Extension HortAnswers. Anthracnose is a disease of privet plants caused by several fungal pathogens including, but not limited to, Apiognomonia errabunda, Apiognomonia veneta, Colletotrichum gloeosporioides and Gnomonia species, according to the University of California IPM Online. Cercospora leaf spot is caused by a fungal pathogen of the Cercospora species, according to the Clemson Public Service Activities.
Also attacking other hosts like barberries, azaleas and magnolias, gray mold disease overwinters on plant tissue and spreads sporadically on wind and water from infected hosts to healthy hosts. In moist conditions with a temperature range of 32 to 84 degrees Fahrenheit, fungi germinates and infects privets after entering through wounds or natural openings in plant surfaces. Anthracnose disease attacks twigs and leaves after overwintering in plant debris and spreading sporadically on water and wind until landing on growing host plants. Widely observed in privet plants, Cercospora pathogens inhabit fallen plant parts like leaves and spread sporadically by wind and rain, according to the Clemson Public Service Activities.
With gray mold, look for twig blight and the formation of gummy areas of foliage. A webbed mold-like substance on plant tissue, referred to as mycelium, often forms in a gray hue, as suggested by the name. Your privet plant may experience diminished vigor and cosmetic damage. In a moist environment, fungal infection of anthracnose leads to dark spots on leaf surfaces, malformed leaves, branch dieback and the development of cankers, or lesions of dying plant tissue. With cercospora leaf spot, look for early leaf drop that may lead to severe defoliation as well as yellow spots surrounded by purple borders on leaf surfaces, particularly during the end of the summer season and autumn, according to the University of Florida IFAS Extension.
For control of gray mold, provide optimal maintenance of your plants as vigorous privets are more capable of resisting disease. Avoid overhead irrigation that provides an ideal environment for fungal germination. Remove and destroy affected plant parts. For anthracnose control, avoid the susceptible common privet (L. vulgare) and choose more resistant varieties like Amur (L. Amurense) or Regal (L. obtusifolium 'Regelianum'). Additionally, remove and destroy affected plant parts and avoid overhead irrigation. For control of cercospora disease on privet plants, avoid overhead irrigation and remove and destroy infected plant parts.
For chemical control of gray mold, contact a local county extension agent or a licensed professional in extreme cases to discuss potential fungicidal treatments. Fungicides do not offer control for anthracnose on privet plants. For chemical management of cercospora spot, apply a chemical with the active ingredient azoxystrobin or myclobutanil, according to the Clemson Public Service Activities.