I I I 2 



THE BOOK OF GARDENING. 



species it is a wound-parasite. P. sqiiauiostis also occurs on a 

 number of trees, Maple, Oak, Mountain Ash, Horse-Chestnut, 

 and many others. The semi-circular sporophores are yellowish- 

 white on top, with darker scales (hence the specific name). 

 Then there are also the destructive and distinctive P. betulinus^ 

 on Beech, and P. d?yadei(s, on Oak, both having hoof-like 

 sporophores, and many others. 



PoLYSTiGMA RUBRUM. — This is a well-marked fungus attack- 

 ing Plums (both w^ild and cultivated), Bird Cherries, &c. The 

 leaves are frequently disfigured by somewhat roundish patches ol 

 a reddish colour, which, after a time, thicken. The disease is 

 not a virulent one, and, moreover, is easily controlled by burning 

 the infested leaves as they are shed. 



Rusts {Uredineai). — These fungi are almost as familiar as the 

 Mildews. They differ, however, from the latter in many im- 

 portant details. One is that the mycelium instead of being on 

 the outer surface is intercellular — in the leaf or bark-tissues, 

 as a rule. The life-histories of many are quite unknown, more 

 particularly those species which are heteroecious. One of the 

 best known of these Rust fungi is the Rose Rust (yPhi-aginidiuin 

 subco7'ticatuiii)^ whose deep yellow patches may be found alike 

 upon foliage and shoots of garden and wild Roses. Another 

 familiar species is that causing Rust of Wheat {Piiccinia gfaini7iis), 

 a heteroecious species whose aecidium-form is familiar to gardeners 

 by reason of the orange-yellow spots on Be?'beris in spring. 

 This species develops both uredospores and teleutospores upon 

 wheat and other cereals. The former are bright orange-yellow, 

 and appear in summer, and the latter are dark brown, with 

 a harder coat, and are associated with autumn. The uredospores 

 germinate readily in summer as soon as ripe ; but the teleuto- 

 spores are for the purpose of carrying the disease over the time 

 when the host-plant is resting. 



Two other examples of the Rusts may be instanced in the 

 injurious Hollyhock Fungus {Puccinia vialvacearinii) and the 

 Raspberry Rust {Phragmidiiim 7'ubi-idcei). Weak Bordeaux 

 Mixture is useful in both the aecidium and uredospore con- 

 ditions ; but the teleutospores, which are in the soil, are difficult 

 to reach. Quicklime, where it can be applied with safety to the 

 roots, might be useful; while the burning of all leaves, fruits, 

 &c., from infested plants will also help to lessen the attack the 

 following season. In the case of heteroecious species like 

 Puccinia gi^aviinis^ whose aecidium-stage, as previously stated, 

 is passed on BerbeiHs ; or Gymuosporangium sabinoe (destructive 

 to Pear foliage), and whose teleutospore stage is passed upon the 

 Common Juniper {/tniiperiis comvninis) and other species, care 

 should be taken to uproot and destroy both the Barberry and 

 the Juniper if they can be traced, often a matter of great 



