DISEASES OF HARDY PLANTS. 229 



before the iiowering period, and causes the sterns to droop 

 and the leaves to shrivel and die. Another disease, called 

 the Pjvony Eust (Gronartiiim pcieonite) attacks the under 

 sides of the leaves in the form of bright yellow or rnsty 

 pustules. 



Kemedt. — The only one is to promptly cut off and burn 

 all diseased leaves and stems to destroy the fungus. 



Sweet Pea Bligfht (Peronospora trifoliorum).— A 

 fungoid disease frequently met with on plants of the pea 

 family (Leguminosie). It first appears in the form of 

 yellowish blotches on the leaves, these eventually becom- 

 ing covered with a dense grey mould, the fruiting stage of 

 the fungus. The disease gradually spreads to the shoots 

 and seed pods, and the result is crippled growth and the 

 eventual death of the plant. 



Remedies. — In the case of badly-infected plants, pull 

 them up and burn them, and especially burn all dead 

 haulm in the autumn, as the winter spores hibernate in 

 these, and are liable to give birth to the summer form of 

 the fungus the next season. Spraying with a solution of 

 soft soap and sulphide of potassium is a good preventive 

 I'emedy. Dissolve 3oz. of soft soap and loz. of the potas- 

 sium in lint water, and add water to make two gallons. 



Sweet Pea Mildew (Erysiphe polygoni). — Another 

 fungoid disease attacking the leaves, stems, and seed-pods 

 in dry seasons. The white mealy mould, indicating its 

 presence on the plants, is the fruiting stage of the fungus, 

 the mycelium, or plant form which produces the fruit 

 (spores), having previously estabhshed itself in the tissues 

 of itis host, and thereby injured the cells. The winter or 

 resting spores consist of minute black spots, which in the 

 following spring produce the mycelium that injures the 

 plant. 



Eemedies.— Dust the plants occasionally with a mixture 

 of four parts of flowers of sulphur to one of quicklime from 

 the time the plants are 1ft. to 3ft. high, and burn all 

 badly-diseased plants, also old haulm, in autumn. 



