372 



STATE BOARD OF AGRICULTURE. 



too, is subject to this disease which often attaclvS the blossoms, leaves and young 

 shoots as well as the fruit. It is also not uncommonly found on apples, especi- 

 ally early varieties, and has been induced to grow on raspberries, blackberries 

 and numerous other fruits. In fact this is one of those fungous pests which seem 

 capable of adapting itself to almost any of the horticultural fruits although it 

 is especially common on the stone fruits. Among plums, the Japanese and Ameri- 

 can varieties seem less subject to the brown rot than the European or "Domestica" 

 type. Of the latter the Lombard is especially subject to this disease. 



The disease manifests itself on the fruit by the formation of a rapidly enlarg- 

 ing, brown discoloration, hence the name brown rot. Sometimes only a few hours 

 are needed for this fungus to cause the decay of affected specimens. Plums 

 which have been bitten by the plum curculio and the plum gouger are almost sure 

 to decay by means of the brown rot, the spores of which are enabled to infect 

 the fruit in these wounds. After the disease is well established the epidermis 

 of the fruit becomes ruptured in many places by the spore-bearing branches of 



Fig. 23. — a, section through a diseased phira showing a spore pustule bursting through the 

 .skin of fruit and producing cliains of spores (conidia); b, part of a spore-chain; c, spores 

 germinating in a drop of water (all highly magnified); d, an old mummy plum wliicli has 

 lain on the ground over winter, giving rise to small fleshy outgrowths (ascophores in form 

 like little wine glasses; e, one of these outgrowths somewliat enlarged; f, some of the 

 slender spore sacs (a.sci), which line the cup like part of the fleshy organs shown at d, e; 

 g, mature spores from a spore sac, h'ghly magnified. (Original.) 



the mycelium which push out in little tufts. These ash-colored tufts have a 

 powdery appearance due to the great number of spores (conidia) given off. When 

 several plums are in contact with an affected one they are all pretty sure to 

 rot and instead of falling off remain on the trees nearly all winter. One of the 

 most common sights in the average plum orchard during winter is furnished by 

 these mummy fruits which were attacked by the brown rot during the previous 

 summer. In spring these diseased plums become softened by rain and the dormant 

 mycelium which they contain may give rise to another crop of spores (conidia). 

 Another spore-form has been recently discovered. Thus when the mummified 

 fruits have lain partly covered with soil on Ihe ground they may give rise in 

 spring to little fleshy outgrowths somewhat resembling wine glasses with long 

 stems. The cup-shaped part of these outgrowths is lined with a spore-bearing 

 layer in which are minute spore sacks (asci) each containing eight spores. 

 When mature these spores are discharged and may infect the new crop of fruit. 

 The brown rot fungus sometimes attacks the tender foliage and young shoots 



