Which of the following diseases is associated with Rhizoctonia sp.?

Brown patch is indeed associated with Rhizoctonia sp., specifically Rhizoctonia solani, which is a significant fungal pathogen known to affect turf grasses and other plants. This disease manifests as circular patches of dead or dying grass, often appearing in warm, humid conditions.

Rhizoctonia typically thrives in conditions where moisture is high, and temperatures are conducive to fungal growth. The lesions created on the plant can be quite distinctive, leading to the characteristic brown patches that can spread rapidly if not managed properly.

In contrast, powdery mildew is caused by a different group of fungi, including species from the genera Erysiphales. Root knot is caused by nematodes from the genus Meloidogyne, rather than fungi, while white mold (also known as Sclerotinia) primarily involves the Sclerotinia genus, not Rhizoctonia. Therefore, recognizing the specific association of brown patch with Rhizoctonia sp. is crucial for effective management and control of the disease in agricultural and horticultural practices.