Pests and Diseases on Chives

I am interested in the pests and diseases on chives (Allium schoenoprasum).

The only pest we have encountered on chives is an unidentified aphid that attacks the base of the plant, close to the soil. These were easy to clear up using several applications of insecticidal soap spray. There is some anecdotal evidence that chives are susceptible to thrips, but that remains to be proven. Otherwise, chives is been relatively trouble-free among the herbs.
Some diseases that have been reported on chives are downy mildew (Peronospora destructor), rust (Puccinia porri) and smut (Urocystis cepulae). Our impression is that these tend to be opportunistic in nature and are not significant in plants that are provided good growing conditions.
Chives require a cold dormant period to thrive. Unless we move pots outdoors to expose them to killing frosts chives do not do well past the first year. This is why chives do not succeed well outdoors in tropical and sub-tropical areas.
Addendum from W.L.M. Tamis:

Thank you for your answer.
In the literature I encountered the following pests and diseases of chives. Especially the susceptibility to the stem and bulb nematode is very worrying. Pests and Diseases of Chives (Allium schoenoprasum)
Common diseases of Allium:

• Pythium spec. (Damping off)
• Botryotinia squamosa (Botrytis squamosa) (Leaf blight, Leaf rot) Urocystis cepulae (Onion smut)
• Botrytis aclada (Neck rot)
• Thrips tabaci (Onion thrips)
• Ditylenchus dipsaci (Stem and bulb nematode)

Diseases Specific to A. schoenoprasum:

• Stromatinia cepivorum (Sclerotium cepivorum) (White rot) Puccinia alli (P. porri) (Rust)
• Acrolepiopsis assectella (Leek moth)
• Onion mite-borne latent (?) potexvirus (common name?)

Occasionally on A. schoenoprasum:

• Peronospora destructor (Downy mildew)
• Alternaria porri (Purple blotch)
• Colletotrichum dematium f.sp. circinans (Smudge) Puccina mixta (Rust)
• Uromyces ambiguus (Rust)
• Sclerotium rolfsii (common name?)

Thank you for sharing your research results. Nematodes are a serious problem in many areas of the world. The Mexican marigold (Tagetes minuta) is proving to be an effective control of many kinds of nematodes. In Holland and in Africa the Mexican marigold is grown as a crop over one season and then plowed under. We do not know if the stem and bulb nematode responds to Tagetes, but it is worth a try if the nematode is a problem in your area.