200 Diseases of Economic Plants 



numerous, black pycnidia, so small as to remain unnoticed 

 unless by special search. The injury is usually insignificant, 

 though some dwarfing and curling of the leaf results. Upon 

 seed plants these same diseases attack the leaves with 

 greater vigor, causing pale brown, discolored areas and 

 the death of the older leaves. Sometimes, through neglect 

 to destroy plants of the seed bed, these diseases may gain 

 such foothold as to cause injury in other beds. This can 

 usually be avoided l^y destruction of the seed-bed plants as 

 soon as transplanting is over. 



Root-knot (nematodes) occurs on lettuce, doing some 

 damage. 



MANGOLD a«d MANGEL WURZEL. See beet. 

 MELON. See cucumber. 



MUSHROOM 



Mold -•^'' {Mycogone perniciosa Magn.). — Though noted 

 in Germany as early as 1887 this disease was not called to 

 attention in America until 1909. 



French experts detect the disease first in the spawn as 

 an abnormal, white, fluffy growth. Later the mycelium of 

 the mushroom fails to develop normally, but instead pro- 

 duces monstrous soft growths. Whole clumps develop 

 into moldy masses, which soon putrify with a clisagreeable 

 odor. 



Infested beds or houses may be aliandoned or cleaned 

 thoroughly, then fumigated with formalin, 3 pints, per 1000 

 cubic feet of space. 



Bacterial-spotting.-^^ Small areas, pale yellow to brown, 

 on cap, stipe, or gills, or even covering the whole plant, 

 occur. Fumigating the beds with sulfur before planting has 

 given excellent results. 



MUSKMELON. See cucumber. 



