Seed-borne Fusarium pathogens in agricultural crops

Abstract

Diseases caused by Fusarium spp. occur worldwide throughout all production areas of edible and ornamental plants as well as tree plantations. Fusarium spp. cause yield losses of up to 80% in both field- and greenhouse-grown crops, resulting in serious economic losses. It is known that plant material such as fruits and seeds as well as soil, can be a pathway of disease transmission; therefore, different strategies to control Fusarium have been used e.g., planting new cultivars, grafting, using inorganic and organic substrates, soil solarization, biofumigation and seed treatments. Nonetheless, new Fusarium pathotypes are often detected or reported to be the causal agents of diseases. To determine the pathway of Fusarium transmission, specifically through seed, is challenging and scientific reports in this regard are lacking. To prove that seed is the pathway of pathogen transmission is time-consuming and laborious, since pathogenicity tests with several Fusarium isolates must be conducted during several growth stages of the host. The isolates then have to be re-isolated from infected plant parts to confirm Koch's postulates and seeds from inoculated plants need to be obtained which in turn need to be tested again for the presence of the pathogen. To prevent the introduction and distribution of Fusarium spp., growers (for local and export markets), technical advisors, and seed producers need to use disease-free seed. The potential production of Fusarium mycotoxins during storage is an additional concern when using Fusarium infected seeds for food. Depending on the region, it is important to know which crops (hosts) are susceptible to a particular Fusarium sp., how this pathogen can be avoided, and how to produce and select healthy fruits and seeds. Efforts must be directed towards avoiding seed contamination with pathogens and developing or optimizing seed health testing methods to detect Fusarium.