Treatment Plan

Cultural practices used to reduce the incidence of angular leaf scorch include planting varieties less susceptible to the disease, increasing air circulation in the vineyard, destroying leaf litter by cultivation prior to bud break, and removing wild grapevines and Virginia creeper in hedgerows and woods bordering vineyards.

Where control is needed, fungicides should be applied before rainfall, beginning at 3” shoot growth through fruit harvest. Although not specifically labeled for control of angular leaf scorch, mancozeb products applied according to label directions to control Phomopsis, black rot, and downy mildew have provided good control of the disease. Mancozeb is the active ingredient in Dithane F-45 Rainshield (liquid formulation) and Manzate Pro-Stick Fungicide (dispersible granules). The maximum allowance for all products containing mancozeb ranges from 18-19.2 lb of active ingredient per acre per season. At the maximum use rate, Dithane or Manzate Pro-Stick can be used up to six times per season, but not within 66 days of harvest. For applications at 3-5” shoot growth, apply 1.6 to 3.2 qt Dithane or 2-4 lb Manzate Pro-Stick; for applications at 10-12” shoot growth through the immediate pre-bloom spray, apply 2.4 to 3.2 qt Dithane or 3-4 lb Manzate Pro-Stick; for post-bloom application, apply 3.2 qt Dithane F-45 or 4 lb Manzate Pro-Stick. 66 day PHI, 24 hr REI for listed mancozeb products.

Pristine Fungicide is labeled for control of Angular Leaf Scorch, but due to the concern for development of powdery mildew and downy mildew resistance, use of Pristine and any other strobilurin (Group 11) fungicides should be limited to a maximum of two applications per year, and should be saved for the immediate pre-bloom stage or later when they are likely to be most beneficial. For further discussion of the use of Pristine, refer to: https://abigailsgarden.com/pages/powdery-mildew and https://abigailsgarden.com/pages/downy-mildew.