642 INSECTS AFFECTING VEGETATION 



MAPLE. 



Anthracnose (Gloeosporium apocryptum). This disease at- 

 tacks young Norway maples (see N. Y. Sta. Report '95) and has 

 been also identified on the young shoots of sugar maples in Ohio. 

 The new leaves were reported destroyed by the fungus which is much 

 more common in Ohio on sycamore trees. Applications of Bordeaux 

 mixture should check this disease. 



Rhytisma and Leaf-spot. The leaves of cultivated maples are 

 often disfigured by dark colored incrustations following the line of 

 the veins. These incrustations are almost black and are caused by 

 a fungus (Rhytisma acerinum). The trouble is usually not serious, 

 but if prevalent it would seem advisable to gather and burn all leaves 

 attacked by it. The leaf-spot fungus (Phyllosticta acericola) often 

 causes small spots, or dead areas, in the leaves. This may sometimes 

 prove so serious as to call for applications of fungicides. 



Mildew. Maple leaves are overrun by the powdery mildew 

 fungus (Uncinula) at times, but this is not difficult to check even if 

 spraying becomes necessary. 



Tip-Burn Sun-Scald. Tip-burn conditions upon the maple 

 in 1908 and 1909 were similar to those described for horse chestnut 

 and evidently due to secondary consequences of insect punctures. 



Sun-Scald or Winter Injury. These are frequent upon maples 

 after the manner of those described for apples. They are due to a 

 killing of unripened tissues by premature freezing and are only pre- 

 ventable by avoidance. 



OAK. 



Anthracnose. The oak leaves are attacked by the same anthrac- 

 nose fungus as attacks the leaves in young shoots of sycamore and 

 maple, but this is not so prevalent upon oaks in Ohio as upon the 

 sycamore. (Ohio E. S. B. 214.) 



PINE. 



Damping-Off. A damping-off fungus (Fusarium) has recently 

 been very troublesome with seedlings of white pine in the east. This 

 has been investigated and remedies have been tried successfully. 

 These are either dilute sulfuric acid or powdered copper sulfate and 

 lime ; the former being sprayed on the seedlings about the base and 

 the latter applied as dust. It is likely that with efforts to grow white 

 pine for timber purposes in this state, troubles of this type will not 

 be restricted to this parasite. 



Leaf Blight and Leaf-Spot. Leaf troubles have been met in 

 most areas where white pine grows naturally or is being cultivated 

 very largely. One of these so-called leaf blights is referred to a fun- 

 gus (Septoria parasitica). It has been found in adjoining states if 

 not in Ohio. Another leaf-spot fungus (Phoma strobi) is quite prev- 

 alent upon white pine in Europe. It is believed that this parasite 

 or a closely related one (Phoma strobilinum) occurs within our 

 borders. Remedies have yet to be worked out for these troubles. 



Root-Rots. These are to be expected in addition to the damp- 

 ing-off fungus before mentioned, especially among seedling pines 

 under culture. 



