White mold

White mold, caused by fungi of the genus Sclerotinia, is a devastating plant disease with a worldwide distribution. The pathogen produces survival structures called sclerotia, which can remain dormant in the soil for several years. This ability to survive makes Sclerotinia a persistent threat to agricultural fields.

The fungus is polyphagous and affects hundreds of plant species, including major crops like sunflowers, oilseed rape, soybeans, beans, and various vegetables. It causes significant economic losses by reducing both the yield and the quality of harvested products, often leading to total crop failure in heavily infested areas.

The primary symptoms include the development of soft, water-soaked lesions that eventually become covered with a fluffy, white mycelial growth. As the disease progresses, the internal tissues of stems or pods decompose, and the characteristic black, hardened sclerotia are formed inside or on the surface of the plant tissue.

Conditions favoring Sclerotinia development include high humidity, moderate temperatures, and limited air circulation. Ascospores are released from the apothecia and spread by wind over long distances. Rain or heavy dew allows the spores to germinate on plant surfaces, facilitating the rapid spread of the infection through the field.

Management strategies are multifaceted and focus on reducing the inoculum density. Essential measures include selecting resistant or tolerant varieties, utilizing wide row spacing to improve canopy aeration, and strict crop rotation with non-host plants. Proper management of irrigation and nutrient levels, combined with the application of specific fungicides during the flowering stage, provides effective control against the disease.