76 ILLINOIS NATURAL HISTORY SURVEY CIRCULAR 46 



This fungus produces two types of growth — slender, flattened, 

 dark red, rootlike strands (Fig. 71) and white mycelial fans (Fig. 

 72) beneath the bark of infected trees. The rootlike strands or 

 shoestrings which grow in the duff and soil around infected trees 

 are round, black, and about one-sixteenth inch in diameter. Since 

 weakened and injured trees are most susceptible to this disease, 

 maximum protection can be obtained by avoidance of root in- 

 juries and by applications of plant food to maintain vigorous 

 growth, as described in the section "Feeding." 



PINE 



Pine is affected occasionally by needle blight diseases and 

 by a tip blight disease. The white pine blister rust has been 

 known in Illinois since 1946, when it was found in Jo Daviess 

 County. 



Needle Blight. — This leaf disease, mainly of Austrian pine, 

 is caused by the fungus Dothistroma jmii. It appears in late sum- 

 mer as slightly swollen, dark spots or bands on 1-year-old needles. 

 The part of a diseased needle from the swollen area to the tip 

 turns light brown and dies. The swollen areas, produced by 

 growth of the fungus in the needles, do not enlarge during the 

 fall and winter months. However, they begin to enlarge in 

 March. By May they appear as dark brown to black, raised fruit- 

 ing bodies visible through fissures in the needles (Fig. 73). 

 Spores produced in these fruiting bodies can cause new infec- 

 tions. Affected trees show sparse foliage, since the diseased 

 needles drop prematurely. 



Spraying with organic mercury or copper sulfate and hy- 

 drated lime during April and early May should control needle 

 blight (Table 1). The first spray should be applied about the mid- 

 dle of April. In wet seasons, a second spray should be applied 3 

 weeks after the first spray. 



Needle Cast. — This leaf disease, caused by several species of 

 fungi of the genus Lophodermium, produces reddish-brown spots 

 or elongate areas on affected needles. Fruiting bodies of the asso- 

 ciated fungus appear as small, black, oval spots on the diseased 

 portions of needles (Fig. 74) . Needle cast seldom causes sufficient 

 damage to warrant control treatment. Spraying with copper sul- 

 fate and hydrated lime, as indicated for tip blight (Table 1) has 

 been reported to control needle cast. 



Needle Rust. — This fungus disease, mainly of red pine, de- 

 velops in the spring as cream- to orange-colored, baglike pustules 



