696 



PARKS 



the present time. If the lawns are much frequented, the soil about the 

 trees becomes trodden and packed, interfering with both aeration and 

 water supply of the roots. Finally, the trees of city parks, like the trees of 

 city streets, suffer from smoke and fumes. Conifers are usually the first to 

 succumb. There is no remedy for this condition except the planting of 

 trees that are smoke resistant, such as the holly, the ginkgo and the sycamore. 

 In the average park many trees are hollow as a result of early injuries. 

 It is customary in many places to fill these hollow trees with cement, wood, 

 magnesite, asphalt mixtures and various other substances. While such 

 filling makes a tree look neat and hence may be desirable in trees located 

 in very conspicuous positions, there is little scientific evidence that cavity 

 filling prolongs the life of a tree or materially strengthens it, and as cavity 

 filling is expensive the park manager must decide whether his available 

 funds are not better spent in other processes. A badly decayed tree should 

 be replaced with a new and healthy tree unless there is some very special 

 reason for trying to prolong its life. 



SPECIFIC 



ASH. Rust (Puccinia fraxinata). Found in the 

 Eastern and Central States. Irregular swellings on 

 twigs and petioles. Also attacks the leaves. Affected 

 areas covered with yellow pustules. Requires marsh or 

 cord grass as alternate host. Control: Trees should not 

 be grown in or near marshy land. 



CATALPA. Leaf spot (Phyllosticta catalpa). Found 

 in Eastern, Southern and Central States. Circular 

 brown spots scattered over leaf surface, slightly de- 

 pressed, causing wrinkling of leaf. If very numerous, 

 the spots coalesce. Control: Spray trees with Bordeaux 

 (2-2-50) at intervals of about two weeks during the 

 summer. Use Bordeaux (4-4-50) in fall and early 

 spring. Keep soil cultivated about the trees. 



ELM. Leaf spot (Gnomonia ulmea). Occurs in 

 Eastern and Central States. Gray and black spots on 

 upper surface of leaves. If severely infected, leaves 

 turn brown and fall early. Control: Rake up and burn 

 all fallen leaves. Spray in early spring, before growth 

 begins, with Bordeaux (4-4-50). A second or third 

 application may be necessary before midsummer. 



HORSE-CHESTNUT. Leaf blotch (Guignardia ezsculi). 

 Occurs in the Eastern, Southern and Central States. 

 Reddish brown, irregular blotches on leaflets, sur- 

 rounded by yellowish zone merging into the green of 

 leaflets. Greater part of leaf surface may be discolored. 

 Leaves begin to fall early by last of August. Occurs only 

 on buckeye. Control: Spray with Bordeaux (4-4-50). 

 Infected nursery stock should be dusted with mixture of 

 nine parts finely ground sulphur to one part arsenate of 

 lead. Rake up and burn all fallen leaves in autumn. 



MAPLE. Wilt (Ferticillium). Found in eastern 

 United States. Leaves on individual limbs or parts of 



DISEASES 



tree wilt and die. Fungus grows in sapwood of tree, 

 producing characteristic dark green streaks. Control: 

 Not successful on individual trees. Wilted limbs should 

 be burned and wounds painted. Often best to remove 

 tree immediately to retard infection of surrounding 

 healthy trees. 



Anthracnose (Glasosporium apocryptum). Occurs in 

 eastern United States. Irregular brown blotches ex- 

 tending from margins of leaves downward along veins. 

 Moist weather favors its spread. Control: Spray trees 

 in early spring with Bordeaux (4-4-50). Two or three 

 applications may be necessary. Rake up and burn all 

 infected leaves. 



Leaf spot (Phyllosticta minima). Occurs in eastern 

 United States. Light brown circular spots with dark, 

 reddish brown margins. Common on red and white 

 maples. Control: Destroy by burning all fallen leaves. 



Tar spot (Rhytisma acerinum). Found in Eastern and 

 Central States. First appears as light green or yellowish 

 spots, which become black, resembling tar. Leaves fall 

 early. Affects only white and red maples. Control: Rake 

 up and burn all fallen leaves. Spray with Bordeaux 

 (4-4-50) in early spring before growth begins. 



OAK. Anthracnose (Gnomonia veneta). Occurs in 

 Eastern and Central States. White oaks particularly 

 susceptible. Brown blotches or spots of irregular shape, 

 particularly along veins of leaves. Moist weather favors 

 spread of disease. Control: Spray trees with Bordeaux 

 (4-4-50) before growth begins in spring at intervals of 

 two weeks. Spray again in fall, and also rake up and 

 burn fallen leaves. 



Leaf blister (Taphrina coerulescens). Found through- 

 out the United States. Begins as yellowish spots on 



