Lupin phomopsis blight

Diaporthe toxica is a fungal pathogen responsible for phomopsis blight in lupin crops. This fungus is specifically known for its ability to produce potent mycotoxins known as phomopsins, which present a severe health risk to livestock consuming contaminated plant material, leading to a condition commonly referred to as lupinosis.

Symptoms of the disease initially appear as small brown spots on the stems, leaf petioles, and pods of the lupin plant. As the infection progresses, these lesions expand, eventually encircling the stem and causing internal tissue decay. This makes the plant structure weak, significantly increasing the risk of lodging before harvest.

The development of Diaporthe toxica is highly dependent on environmental conditions, particularly high humidity and moderate temperatures during the growing season. The fungus overwinters in crop residues and stubble left in the field. Spores are primarily dispersed through wind and rain splash, infecting healthy tissues during periods of rapid plant growth.

The economic impact of this pathogen is twofold: it reduces seed yield and quality while simultaneously rendering the lupin crop dangerous for agricultural use. Because the mycotoxins can remain stable in the plant material for long periods, harvesting and storing infected crops requires strict quality control measures to prevent animal poisoning.

Effective control of phomopsis blight relies on an integrated management strategy. This includes maintaining an appropriate rotation period, as the fungus can persist in the soil and residues for several years. Selecting resistant lupin varieties, employing clean seed stocks, and ensuring that any infected crop stubble is deeply buried or removed can significantly reduce the risk of future outbreaks.