DISEASES OF CULTIVATED PLANTS, 445 
Broom-Rape. In certain infested districts in Brown county the common 
broom-rape (Orobanche Ludoviciana Nutt. } attacks the roots of tobacco, while ey 
in Kentucky the hemp broom-rape (QO. ramosa) also occurs even to a greater 4 
extent than in Ohio. Nothing can be done to prevent these attacks of this para- 
site which produces its own. flowers and seeds after once established. If losses 
are large it would be wise to rotate crops on infested land to get rid of the 
broom-rape. 
4) 
Fig. 94. Roots of white burley tob plant attacked by broom-rape. Each of these masses 
attached to the root shows beginning of the plant which will grow up in larger dense form, and produce 
an abundance of blossoms and seeds but no leaves. Each one of these must have started froma 
buried seed of the broom-rape, Orobanche Ludoviciana Nutt. 
Curing House Troubles. At times tobacco growers have in very moist weather 
troubles from rotting in the curing house. . These are called shed-burn, pole- 
burn, etc., and are difficult to control under unfavorable weather conditions. 
Thorough ventilation of the houses is certainly-necessary where these are feared. 
Downy and Powdery Mildew (Peronospora sordidaB. & B.) and (Erysiphe 
communis Wallr.) both occur in the old world, but up to this time have not been 
listed in America. 
Leaf-Spot (Cercospora nicotianae E. & E.) (Phyllosticta nicotiona E. & E.) 
occurs in some tobacco states, but is very rare with us. 
Mosaic Disease also among the enzymatic diseases, is not very common upon 
tobacco, except in seasons when the normal development of the plants is inter- 
fered with by excessive rains and water logged soils. In Connecticut the disease © 
is known as ‘‘calico,’’ diseased plants showing a mottled appearance due to 
the alternating areas of dark green and yellowish green in them; they are 
