Basal Rot

• Basal rot is a fungal disease caused by cylindrocarpon, which effects Oriental lilies, and the more damaging fusarium oxysporum var lilii, which attacks Asiatic lilies. Pathogens enter the roots and first appear as a dark brown rot, and the fungi will quickly extend into the scales of lilies from the basal plate. Premature aging of foliage, detached scales and stunted stalk growth are all signs of basal rot, with a dead flower and destroyed bulb the end result. The stem bulblets, however, are rarely infected and suitable to plant.
  
  

Botrytis

• Botrytis is a disease that only effects the surface of lilies and is caused by two different, but related, species of fungi: B. cinerea and the more destructive B.elliptica. Both strains can occur on the flower simultaneously, with each showing its own signs. Careful watering practices are necessary to avoid the spread of spores since they are easily transferable to other surfaces of the same flower or neighboring blooms. Botrytis first appears as white spots that quickly turn to teardrop-shaped spots with light margins and dark centers that do not fade. Leaves or the entire flower will eventually decay, collapse and die.
  
  

Cucmber Mosaic Virus

• Easily spread from lily to lily, the cucumber mosaic virus can cause streaky colors, brittle or misshapen foliage and stunted plant growth within a matter of weeks. With a wide variety of host plants, the cucumber mosaic virus can quickly appear throughout a garden and is often spread by aphids looking for food. Only the seed can be salvaged from infected lilies, as the cucumber mosaic virus corrupts the DNA of the rest of the flower.
  
  

Lily Symptomless Virus

• Stunted petal and plant growth are the only visible signs your flowers may be infected with the lily symptomless virus. It is the most common virus to affect pure species and hybrid lilies, and what makes it so dangerous is that it is easily transferable and leaves the flower more susceptible to the attacks of other diseases and viruses.
  
  

Tulip Breaking Virus

• The tulip breaking virus is what causes the streaking colors in some Dutch tulips, but the virus can wreak havoc on lilies. Molted foliage, weak colors and streaks in the petals are all tell-tale signs that a lily has been infected with the tulip breaking virus. Since the virus is so easily transferable, it is wise to keep any "painted tulips" separate from lilies in any flower garden.