240 Diseases of Greenhouse Crops 



rapidly and causes great damage. According to 

 Spaulding* no one variety or color of chrysanthe- 

 mum showed any difference in resistance. 



Besides chrysanthemums the disease also attacks 

 poinsettias (Euphorbia pulcherina). In this case 

 the projecting angles on either side of the leaf be- 

 come affected. It seems that with poinsettias, infec- 

 tion is localized in the broad green leaves which 

 grow along the stems below the red zones. At the 

 place of infection there is an exudation of small 

 white drops of the hardened juice along the larger 

 veins. These hardened drops of juice on the dead 

 spots are very characteristic of the disease on poin- 

 settias. Infected leaves drop off prematurely, thus 

 marring the appearance of the plant. About two 

 days after infection, the characteristic fruiting of the 

 fungus makes its appearance. 



Phyllosticta Leaf Spot 



Caused by Phyllosticta chrysanthemi E. and D. 



Symptoms. The spots are orbicular, purplish 

 brown with a distinct border. The trouble is mostly 

 confined to the leaves. 



Little is known as yet of the causal organism. It 

 is probable that spraying with a standard fungicide 

 will control the trouble. 



* Spaulding, P., Missouri Botanical Garden, Twenty-first Ann. 

 Rept: 185-188, 1910. 



