Decaying asparagus plants: treatment of asparagus crown and root rots

Asparagus crown and root rot is one of the most economically disastrous diseases of asparagus worldwide. Asparagus crown rot is caused by three species of Fusarium: Fusarium oxysporum f. sp. asparagi , Fusarium proliferatum , and Fusarium moniliforme . These three fungi can invade roots, but F. oxysporum f. sp. asparagi also invades the xylem tissue, the woody support tissue that carries water and nutrients from the roots to the stem and leaves. For more information on the control of crown and fusarium root rot, click here.

Symptoms of Fusarium Crown Rot of Asparagus

Generally referred to as Fusarium disease, asparagus crown rot, seedling blight, decay disease or replanting problems, asparagus crown rot results in reduced productivity and growth, indicated by yellowing, wilting, dry crown rot and eventual death. This soil-borne fungus causes infected areas of the crown to turn brown and then rapidly kill decaying asparagus.

Stems and bark are strewn with reddish-brown lesions and, when open, reveal vascular discolouration. The food roots are almost completely rotten and have the same reddish-brown colouration. Rotted and dying asparagus plants infect each other and the disease can spread exponentially.

Management of Fusarium crown and root rot of asparagus

Asparagus crown rot can survive indefinitely in the soil and is spread by the movement of infected air and soil currents and seed contamination. Plant stress and environmental factors such as poor cultural practices or drainage further open plants to infection. Positive identification of crown rot is determined by laboratory tests.

Fusarium disease is extremely difficult, if not impossible, to manage once in the field. As the saying goes, «the best offense is a good defense,» so watch out for pests and diseases and keep the area around your asparagus crop free of weeds and other plant debris.

In addition, disease-free seedlings, transplants or crowns minimize plant stress, avoid long harvest periods and are compatible with irrigation and fertilization to reduce the risk of Fusarium infection of crops.