Sclerotinia White Mold. In: Compendium of Pea Diseases and Pests

Authors: Porter, Lyndon; WUNSCH, MICHAEL - North Dakota State University; Chen, Weidong

Submitted to: American Phytopathological Society Press
Publication Type: Book / Chapter
Publication Acceptance Date: 7/17/2020
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sclerotinia sclerotiorum is a major ascomycete fungal pathogen causing soft rot of pea foliage worldwide. The disease is known as Sclerotinia rot or white mold. White mold is particularly destructive when the pea canopy is dense, wet and the temperature is around 21C. Excessive soil nitrogen, heavy seeding rates, lodging and pea cultivars that produce a prostrate growth type are conditions that favor white mold development. First signs of infection can often be found after row closure and flowering have taken place and where stems or pods are touching the ground. Infected stems or pods often appear slimy and are tan to brown in color. After infected stems dry, they appear bleached. All above ground foliage of the plant is susceptible to infection. Hard, black survival structures called sclerotia are most commonly produced inside or on the outside of infected stem or pod tissue. Sclerotia can range in sizes but usually are around 3 mm in diameter. Sclerotia are capable of directly infecting plant tissue, but wind dispersed ascospores can also develop from apothecia that are cabable of moving great distances and can cause infection when coming into contact with susceptible host tissue. White mold management options include: avoid cultural practices that favor high humidity and dense plant canopies, orient planting rows with the direction of the prevailing wind to avoid conducive environments for disease development, plant crop rotations with cereals that are non-hosts and use effective available fungicides. Pea germplasm with moderate resistance to white mold have been identified but no commercial resistant cultivars are available.

Technical Abstract: Sclerotinia sclerotiorum is a major ascomycete fungal pathogen causing soft rot of pea foliage worldwide. The disease is known as Sclerotinia rot or white mold. White mold is particularly destructive when the pea canopy is dense, wet and the temperature is around 21C. Excessive soil nitrogen, heavy seeding rates, lodging and pea cultivars that produce a prostrate growth type are conditions that favor white mold development. First signs of infection can often be found after row closure and flowering have taken place and where stems or pods are touching the ground. Infected stems or pods often appear slimy and are tan to brown in color. After infected stems dry, they appear bleached. All above ground foliage of the plant is susceptible to infection. Hard, black survival structures called sclerotia are most commonly produced inside or on the outside of infected stem or pod tissue. Sclerotia can range in sizes but usually are around 3 mm in diameter. Sclerotia are capable of directly infecting plant tissue, but wind dispersed ascospores can also develop from apothecia that are cabable of moving great distances and can cause infection when coming into contact with susceptible host tissue. White mold management options include: avoid cultural practices that favor high humidity and dense plant canopies, orient planting rows with the direction of the prevailing wind to avoid conducive environments for disease development, plant crop rotations with cereals that are non-hosts and use effective available fungicides. Pea germplasm with moderate resistance to white mold have been identified but no commercial resistant cultivars are available.