Sometimes seeds and/or fruits may carry fungal spores from the field or can develop fungal infestation after collection, especially if they are kept in a warm and humid environment. For this reason, proper ventilation of the seed collection is recommended in order to limit these risks. However, pay attention, as recalcitrant seeds may carry the risk of desiccation. In some cases, wings, hairs, or other appendices of the fruit or seed tend to accumulate moisture and promote fungal attack. Removal of these appendices is often done as a routine prior to transportation or storage.
In the seed bank, it is important to prioritize these seed collections for processing, separating seeds from fruits and other plant material as soon as possible using a special working place to avoid pathogens’ spread. Sometimes, capsules attacked by insects or fungi may not open properly, either because the network of fungal hyphae physically hinder the release of the seeds, or because the infection blocks the normal opening mechanism. The seeds of these fruits can only be extracted by threshing them.
A visual check can help to manually select the seeds already compromised by fungi. However, before discarding any seeds, always perform a cut test on a few of them to assess if the fungi have affected the internal tissues. If seeds look healthy inside, it’s worth keeping them, especially if the species is rare or endangered.
Drying and refrigerating/freezing the seeds will stop fungal growth, but it is unlikely that the fungi will die. Therefore, it is recommended to surface sterilize the seed coat prior to germination (please click here for further details).