372 



ARBORICULTURE 



ARBORICULTURE 



each fall and carefully burned in order to prevent the 

 wintering over of harmful fungi. (4) Care should be 

 taken that all wounds made in pruning or by accident 

 be immediately treated with some waterproof adhesive 

 to prevent infection by wound parasites. In the absence 

 of anything like accurate knowledge concerning better 

 preparations, coal or gas tar and lead paint are to be 

 recommended. The tar will last longer than the paint. 

 The whole idea of wound-protection is to bridge over 

 the time lapsing between the injury and the natural 

 healing of the wound by the callus. Wounds previously 

 treated should be gone over at least once a year and a 

 new coating applied if necessary. 



Prevention of leaf diseases. 



Although the most of the damage done by leaf dis- 

 eases is mainly to the appearance and not to the life of 

 the tree, it may even be desirable to prevent the un- 

 sightly appearance of leaf -spot or other diseases of that 



nature. If, after the 

 sanitary methods de- 

 scribed above fail to 

 control the disease, it is 

 desired to spray, this can 

 be done at some little 

 expense if the trees are 

 not too large. Bordeaux 

 mixture, full strength or 

 half strength, applied 

 three or four times after 

 the leaves begin to 

 show, at intervals of 

 about three weeks, will 

 probably tend to lessen 

 354. Cross-section of maple limb infection in most cases, 

 affected by Fomes igniarius. Note Spray mixtures should 

 that the frost crack was possibly the J,e applied a few hours 

 infection court. A young sporophore ,{,, to epnpra l ra j n 

 is shown just emerging at the top 18 ,V g , ra , 



of the picture. ( x H) periods, the advance of 



which can be predicted 



by observing the government weather maps. General 

 directions about spray mixtures and spraying machinery 

 is now attainable from almost any one of the State 

 Agricultural Experiment Stations. 



Treatment of diseased trees. 



When the woody part of the tree is the diseased 

 area, tree-surgery methods must be used. Badly dis- 

 eased limbs and twigs should be pruned off flush. Never 

 leave a stub. Wounds so made should immediately 

 be coated with a waterproofing. Decayed parts of 

 larger limbs or trunks should be carefully dug out with 

 a gouge and mallet, being sure to remove far back 

 on all sides of the cavity into apparently healthy wood. 

 The growing mycelium of the fungus is advancing some 

 distance beyond the decayed area, in what appears 

 as healthy tissue, and must be removed to effect a 

 stoppage of the decay. Cavities thus made may be 

 filled with concrete or left open, provided, in either case 

 however, that the entire surface exposed is carefully 

 painted with a waterproofing paint or tar. Diseased 

 roots may be treated in the same way. At the 

 present time no method of treating diseased trees 

 internally is known. The ideas of quacks who may 

 advance such treatments should be doubted, for in the 

 majority of cases such treatments will prove to be harm- 

 ful. The matter of chemeotherapy for the cure of tree 

 diseases is not without hopeful outlook, but much care- 

 ful investigation by experts must be forthcoming before 

 such methods can be evolved. \y jj RANKIN. 



Choice of trees for special purposes. 



The following lists include trees of proved hardiness 

 and are not intended to be complete but merely sugges- 

 tive, and chiefly for the northeastern United States and 

 Canada. 



1. TREES WITH SHOWY FLOWERS. 



A. Blooming in early spring before or with the 



leaves. 



Acer rubrum (fls. blood-red). 

 Amejanchier canadensis (fls. white). 

 Cercis canadensis (fls. rosy pink). 

 Cornus florida (fls. white, also pink). 

 Cornus mas (fls. yellow). 

 Magnolia denudata (fls. white). 

 Magnolia Soulangeana (fls. white to purple). 

 Prunus americana and other plums (fls. white). 

 Prunus Avium and other cherries (fls. white). 

 Prunus Davidiana (fls. pink, also white, the earliest of all 



Prunus). 



Prunus pendula (fls. pinkish, branches pendulous). 

 Prunus Sargentii (fls. light pink). 

 Prunus serrulata (fls. white to pink). 

 Pyrus baccata and other species (fls. white to pink). 

 Salix (staminate plants with yellow catkins). 



AA. Blooming late in spring after the leaves. 



^Eseulus Hippocastanum and other species (fls. white or 



red). 



Catalpa speciosa (fls. white). 

 Cladrastis lutea (fls. white). 

 Cornus kousa (fls. white). 

 Cratfegus (fls. white). 

 Fraxinus Ornus (fls. white). 

 Laburnum (fls. yellow). 

 Magnolia hypoleuca (fls. white). 

 Pterpstyrax (fls. white). 

 Robinia (fls. white or light pink). 

 Syringa vulgaris (fls. white to purple). 

 Tamarix parviflora (pink). 



AAA. Blooming in summer and autumn. 



Aralia chinensis and A. spinosa (fls. Aug. and Sept.). 

 Castanea dentata (fls. white; July). 

 Gordonia pubescens (fls. white; Sept., Oct.). 

 Kcelreuteria paniculata (fls. yellow; July, Aug.). 

 Oxydendrum arboreum (fls. white; July, Aug.). 

 Rhus semialata (fls. white; Aug., Sept.). 

 Robinia neomexicana (fls. light pink; Aug.). 

 Sophora japonica (fls. white; Aug.). 

 Syringa japonica (fls. white; July). 



Tamarix gallica (fls. pink; Aug., Sept., if severely cut 

 back). 



2. TREES WITH SHOWY FRUITS. 



Acer pseudoplatanus var. erythrocarpa (fr. bright red). 



Acer rubrum (fr. bright red in May and June). 



Ailanthus altissima var. erythrocarpa (fr. red). 



Cornus florida (fr. scarlet). 



Cotinus coggygria (ample feathery panicles.) 



Crattegus mollis and others (fr. scarlet or red). 



Hippophae rhamnoides (fr. yellow). 



Ilex opaca (fr. red). 



Magnolia hypoleuca (fr. scarlet). 



Magnolia tripetala (fr. pink). 



Pyrus baccata and allied species (fr. yellow or scarlet). 



Rhus typhina (fr. scarlet). 



Sassafras (fr. dark blue with red stems). 



Sorbus americana and aucuparia (fr. red). 



Taxus baccata (fr. scarlet). 



3. TREES VALUED FOR FOLIAGE EFFECTS. 



Section 5, Evergreens, next page.) 

 A. With colored foliage. 



(See also 



Acer Negundo var. argenteo-variegatum (the most effec- 

 tive of hardy variegated trees.) 



Acer Negundo var. aureo-marginatum (Ivs. yellow). 



Acer palmatum var. atropurpureum (Ivs. purple). 



Acer platanoides var. Reitenbachii (Ivs. becoming dark 

 red in summer). 



Acer platanoides var. Schwedleri (Ivs. bright red in 

 spring). 



Acer pseudoplatanus var. Worleei (Ivs. yellowish). 



Betula alba var. purpurea (Ivs. purple). 



Fagus sylvatica var. purpurea (Ivs. purple). 



Populus alba var. nivea (Ivs. white beneath). 



Populus deltoides var. aurea (one of the best yellow- 

 leaved trees). 



Quercus pcdunculata var. atropurpurea (Ivs. purplish). 



Quercus pedunculata var. Concordia (Ivs. yellowish). 



Salix alba var. argentea (Ivs. silvery white). 



Tilia tomentosa (Ivs. white beneath). 



Uimus campestris var. argenteo-variegata (Ivs. whitish). 



AA. With large, bold foliage. 



Acanthopanax ricinifolium. Catalpa speciosa. 



Acer insigne. Magnolia macrophylla. 



Acer macrophyllum. Magnolia tripetala. 



Aralia chinensis and A. spinosa. Paulownia tomentosa. 



Asimina triloba. Quercus dentata. 



