108 SWEET PEAS 



isolated case here and there could have appeared. From the 

 description it was probably the 



Seedling Pea Blight (Brachysporium pisi). This disease 

 attacks the young seedlings. Mouldy black patches appear on the 

 leaves, which turn yellow, and the plants soon collapse. The way 

 to prevent the disease from spreading is to burn all the young 

 plants attacked and spray those remaining with a solution made by 

 dissolving 1 oz. of liver of sulphur and 3 oz. of soft soap in 

 2 gallons of water. 



Mildew (Erysiphe polygontf.The principal cause of mildew 

 is found in sudden climatal changes. A spell of damp, cold 

 weather after a few bright days often causes mildew to appear. 

 The usual remedy is to dust the plants with flowers of sulphur. 



FIG. 12. ROOT-ROT FUNGUS AFFECTING SWEET PEAS 



(Tliiela/oia, syn. Torrila, basicola) 



R, plant collapsing when 12 to 18 inches high : z, growing point stunted, 

 having ceased to develop ; a, leaves browned and curled upwards ; b, side 

 or axillary shoots browned and withered ; c, dark spots on stem near 

 collar ; d, blackish spots on root stem ; <?, roots more or less blackened 

 and destroyed ; /, extremities of roots killed. 



S, collapse of young plant when just springing above ground : g, black and 

 killed underground stem; h, not seriously affected; i, remains of 

 seed-leaves where mycelium probably passed from saprophytic to 

 parasitic mode of life in Sweet Pea stem ; ./, ground level. 



T, plant killed when only a few inches high : k, top growth ceased ; I, 

 blackened stem ; m, roots killed ; n, radicle least affected ; o, remains 

 of seed-leaves. 



U, bit of rather fresh stable manure showing : p, mycelium of fungus as 

 saprophyte. 



V, portion of leaf mould only partially rotted, with #, mycelium of fungus, 

 as a saprophyte. 



W, vegetative portion of fungus from bit of diseased stem of R : r, septate 

 threads, which penetrate the tissues of the host plant 



X, special thread of mycelium pushed externally and prod ucing endospores : 

 , threads bearing the endospore case ; t, point where endospores 

 are pushed out ; u, endospores, 



Y, chlamydospores borne on same mycelium as the endospores : v, endospore 

 thread ; m, chlamydospore thread ; x, chlamydospores ; y, the same 

 breaking up, and acting as resting spores, brown or blackish. 



Z, ascospores containing eight spores : z, free ascospores. 



