Brown patch (large patch or Rhizoctonia blight )
Rhizoctonia solani
Also Known As - Large patch (brown patch or Rhizoctonia blight ),Rhizoctonia blight (brown patch large patch),Damping offWhat is a Brown Patch (Rhizoctonia solani)?
Brown patch, caused by the fungus Rhizoctonia solani, is a widespread turfgrass disease occurring globally. It affects various turfgrass species, including cool season grasses such as tall fescue, Kentucky bluegrass, and perennial ryegrass. The disease manifests as circular patches ranging from a few inches to several feet in diameter, with a dark purple to grayish-brown border known as a "smoke ring." Infected leaves exhibit irregular lesions with purplish to brown borders, eventually turning brown and drying out.
How does the Brown Patch (Rhizoctonia solani) occur?
Rhizoctonia solani reproduces through sclerotia, compact mycelium masses that serve as survival structures. These sclerotia persist in the soil or on plant debris. When conditions are favorable, sclerotia germinate, producing hyphae that infect plants. The fungus can also spread through spores, transported by wind, water, or equipment, facilitating the disease's dissemination to new areas.
Symptoms
2 - Plant damage
• Brown patch (Rhizoctonia solani) cause browning, drying, and death of foliage, reducing growth, thinning, and weakening plant vigor. • Infected plants are more susceptible to stress and may experience a decline in overall health and aesthetic value.
5 - Soil health
Rhizoctonia fungi disrupt soil microbial composition, impacting soil health and nutrient cycling. Furthermore, the persistence of Rhizoctonia allows the disease to persist and potentially reoccur in subsequent growing seasons.
Solutions
6 - Cultural Practices
• Avoid excessive nitrogen applications, as lush growth is more susceptible. • Improve drainage to prevent waterlogged conditions. • Remove dew manually to reduce leaf wetness. • Prune trees and shrubs to improve air circulation and light penetration. • Thatch removal should be considered if it exceeds 0.5 inches. • Plant disease-tolerant cultivars.
8 - Treatment
• Plant biofumigant crops such as mustards (Brassica juncea) in the affected area. • Allow the plants to grow until they reach the flowering stage. • Cover the soil with a plastic sheet or tarp to trap the released gases. • Leave the cover in place for 2-4 weeks, allowing the breakdown of plant tissues to release bioactive compounds that suppress the pathogen.
