Nematodes, or eelworms, are tiny, worm-like creatures that live in the soil. They're microscopic and can't be seen with the human eye. Many groups are nematodes are beneficial in soils; however, some can be plant pathogens.
Eelworms in the group Aphelenchoides are mostly harmless to plants. However, there are a handful of species which can be damaging. These include A. ritzemabosi and A. fragariae, which attack Chrysanthemums and strawberries and ferns respectively.
Symptoms can vary depending on the species of nematode and the host it attacks, but general signs of infection include stunted growth, deformed growth and water-soaked patches on flowers. Because flower growth is impacted the nematodes can influence fruit production, too.