Hyacinth Diseases 271 



Control. Since numerous sclerotia are left in the 

 soil with decayed bulbs, steam sterilization of the 

 soil is recommended. Badly infected bulbs should 

 be removed and destroyed by fire. Plenty of ven- 

 tilation should be provided whenever possible. 



Nematode 



Caused by Tylenchus dipsaci Kuhn. 



Symptoms. This disease was first found in the 

 United States by Byars * on imported hyacinth 

 bulbs. It is prevalent in Europe where it attacks 

 besides the hyacinth, clover, alfalfa, rye, oats, onion, 

 potatoes, and numerous other wild and cultivated 

 plants. 



On the leaves, the nematode produces character- 

 istic distortions and yellow to brown longitudinal 

 discolorations. At the end of the growing season, 

 the parasite migrates from the leaves to the scales 

 of the bulbs. Diseased scales become discolored, so 

 that when one cuts through an infected bulb, one or 

 more yellow characteristic rings become very appar- 

 ent. 



The Organism. The adult worm is barely per- 

 ceptible to the naked eye. It may, however, be read- 

 ily seen with a magnifying hand lens. Each female 

 produces numerous eggs which hatch into larvge, the 

 latter of which reach maturity quickly. This means 

 that several generations are produced in one season. 



Control. The disease is carried with infected 



♦Byars, L. P., Phytopath. 4:45, 1914. 



