Net blotch of barley

Net blotch, caused by the fungus Pyrenophora teres, is one of the most significant foliar diseases affecting barley crops globally. The pathogen disrupts the photosynthetic efficiency of the plant, leading to substantial yield losses if not managed correctly throughout the growing season.

The fungus is primarily seed-borne and residue-borne, meaning it survives on infected barley straw left in fields from previous harvests. Initial infections typically occur in early spring when spores are splashed onto emerging seedlings by rain or carried by air currents from nearby debris.

Symptoms are identified by dark brown lesions that develop a distinct net-like pattern of venation, which gives the disease its common name. As the infection progresses, these lesions merge, causing the leaf tissue to wither and die prematurely, effectively reducing the grain-filling period.

The development of Pyrenophora teres is highly dependent on environmental conditions, thriving in cool, moist weather with high humidity. Rainfall is particularly crucial for the spread of conidia, often leading to rapid epidemics in dense, well-fertilized barley stands during the tillering and stem elongation stages.

Management of net blotch requires an integrated approach to minimize inoculum pressure. This includes the use of disease-free certified seeds, crop rotation to break the survival cycle, and the application of foliar fungicides during critical stages of crop development to preserve the upper leaves for yield formation.

• Use of resistant barley cultivars
• Crop rotation to non-host crops
• Seed treatments with systemic fungicides
• Effective management of crop residues
• Timely application of foliar fungicides based on risk monitoring