152 



Illinois Natiral IIisiorv Sur\ly Hui.lltin 



Vol. 27, Art. 2 



In i-;irl\ Au;j;ust of l'^27 Professor 

 M. J. Dursey of the Universit> of Illinois 

 foiind, in a larj^e orchard near Ccntralia, 

 the first authentic case of peach yellows 

 in Illinois. By 1929 the disease had 

 spread to 37 trees scattered in 11 orchards 

 located in Jefi'erson, Marion, Pike, and 

 Pulaski counties. In recent _\ears peach 

 \ello\vs has not been observed in Illinois. 

 Diseases which are destructive to the 

 peach crop and which have appeared an- 

 nually in recent years are scab, brown rot, 

 shothole, and peach leaf curl. 



Durinji the earl\' years of the plant dis- 

 ease survey, nailhcad canker was a serious 

 disease of apple trees. However, this dis- 

 ease disappeared from the orchards of the 

 state when j^rowers eliminated those va- 

 rieties susceptible to the disease. The 

 majcjr destructive diseases of apples which 

 have continued to appear annually are 

 scab, lircbli^ht, frof^eye, and blotch. Mil- 

 dew has increased in destructiveness in 

 recent years because the sulfur fungicides 

 which controlled the disease in the early 

 years have been replaced by new types of 

 fungicides; these new materials more ef- 

 fectively control the other diseases of 

 apples. Cedar apple rust, which was prev- 

 alent and destructive for many years, is 

 controlled satisfactorily at present by some 

 of the recently developed fungicides, fer- 

 bam plus sulfur on the deciduous hosts, 

 Elgetol and acti-dione on the evergreen 

 hosts. 



Many pear orchards in the state have 

 been severely damaged or destroyed by 

 fireblight. At present there is hope that 

 this disease can be effectively controlled 

 by some of the new antibiotic sprays. 

 Other diseases destructive annually to 

 pear trees are leaf blight and leaf spot. 



The disease most destructive to cherry 

 trees in the state is shothole. Yellowing, 

 necrosis, and premature leaf drop, caused 

 by this disease, gradually reduce the vigor 

 of affected trees and, eventually, the qual- 

 ity and (iuantit\' of cherries produced. 



Diseases that may appear annually on 

 other fruit crops are bacterial spot and 

 black knot of plum ; black rot, downy 

 mildew, and powder\ mildew of grape; 

 crown gall and rust of blackberry ; an- 

 gular leaf spot of currant; leaf spot, leaf 

 scorch, and yellows of strawberry; an- 

 thracnose of raspberry, currant, and goose- 



berry ; and Septoria leaf spot of black- 

 berry and raspberry. Although many of 

 these diseases are not destructive each 

 year, they cause serious losses in some 

 years. 



Vegetable Diseases. — Although 

 vegetable crops are affected by many dis- 

 eases, only a few of the diseases cause 

 serious losses annually. The most com- 

 mon and destructive diseases in Illinois 

 are bacterial blight, halo blight, and 

 mosaic of bean ; yellows of , cabbage ; 

 Ascoch\'ta leaf spot, Fusarium wilt, and 

 powdery mildew of pea; Fusarium wilt, 

 mosaic, and bacterial leaf spot of pepper; 

 early blight, Fusarium wilt, black leg, 

 and scab of potato; and early blight, 

 Fusarium wilt, and Verticillium wilt of 

 tomato. 



Botanical Collections 



The first of the present botanical col- 

 lections of the Natural History Survey 

 was started in a small way in 1921. At 

 that time the collection of plant disease 

 fungi of the Natural History Survey was 

 separated from the collection of the Uni- 

 versity of Illinois. The vascular plants 

 collected with State Laboratory funds 

 and with Natural History Survey funds 

 previous to 1921 were left in the her- 

 barium of the University of Illinois. 



Plant Disease Collection. — The 

 earliest reported specimens in the plant 

 disease collection of the Natural History 

 Survev are several hundred specimens col- 

 lected", 1918-1921, by H. W. Anderson 

 of the University of Illinois. Collection, 

 identification, and preservation of such 

 specimens were expanded rapidly during 

 the four summers of 1921 through 1924, 

 when special emphasis was placed on ob- 

 taining information on the plant disease 

 situation of the state. To conduct this 

 plant disease survey, one to four men 

 were employed full-time each summer to 

 collect specimens of diseased plants in 

 each county of the state. This activity 

 resulted in adding over 18,000 plant dis- 

 ease specimens to the collection. Among 

 these specimens were five plant diseases 

 new to the state and 18 species of plant 

 parasites new to science. 



In 1924 this collection contained type 

 specimens which represented three genera 

 and 73 species of plant-inhabiting fungi 



