Ace the Certified Arborist Test 2026 – Branch Out and Leaf Your Mark!

Brown rot primarily affects cellulose while leaving lignin relatively intact. This type of decay is caused by certain fungi that break down the polysaccharides in wood, which include cellulose but not lignin. This results in a significant loss of structural integrity in the wood since cellulose is the primary component that provides strength and stiffness. As brown rot progresses, it leaves behind a brown, crumbly residue composed mainly of lignin and minerals, which can lead to the characteristic appearance of wood affected by this form of decay.

In contrast, white rot fungi have the ability to degrade both cellulose and lignin, resulting in a lighter-colored, spongy wood that has been extensively decomposed. Soft rot fungi also have a different decay mechanism and tend to affect both cellulose and hemicellulose more than lignin, although they also attack lignin over a longer period. Dry rot typically refers to certain types of wood decay that could involve various fungi and is not specifically related to the cellulose-lignin relationship as brown rot is.