Taxonomy: Fungi, scientific name "Sclerotium cepivorum".

Description: White mat of Fungal growth at the base of the bulb which can develop into black pin head sized fungal formations. The leaves of the onion can also start to die off starting with the older leaves. For more information visit this link. 

Life-cycle: This disease can survive in the soil. 

Control general remarks: Crop rotations are very important. 

Contact a Cropserve agronomist for more information.