FUNGI AFFECTING FLOWERS 



The Hollyhock Rust 



Puceinia malvacearum 



This fungus is a native of Chili, from whence, 

 about 1869, it was introduced into Europe, where it has 

 done much damage. It first appeared on hollyhocks in 

 this country in 1886, having been accidentally imported 

 Into Massachusetts the previous year on another plant. 

 Since then it has gradually spread in various directions. 

 It appears in May and June, in the shape of yellow or 

 orange spots, on the leaves and stems of the holly- 

 hock. These spots occur especially on the under sur- 

 face of the leaves ; they increase rapidly in size, and the 

 yellow color gives way to a brown. The spots, or sori, 

 are composed of two-celled spores. When they are very 

 abundant they cause the plant to become sere and brown, 

 preyenting, in whole or in part, the production of flow- 

 ers. A leaf showing the sori on the under surface is 

 represented in Plate XIII. 



Treatment. — When this disease appears in a new 

 locality for the first time the best method will be to pull 

 up and burn the affected plants at once. European 

 gardeners have reported successful results from spong- 

 ing all diseased parts of the plants with a mixture made 

 by adding two tablespoonfuls of saturated solution of 

 permanganate of potash to one quart of water. It seems 

 probable that thorough spraying with some fungicide 

 like the Bordeaux mixture or the ammoniacal copper 

 carbonate solution, would prove helpful. In any case, 



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