99 



critical time. To meet this requirement I have prepared the fol- 

 lowing- brief paper, which is a re-statemetit merely of the essential 

 facts concerning- the most important nursery pests likely to occur 

 in Illinois nurseries and to spread abroad in spring- or fall in the 

 course of the reg-ular nursery trade. Althoug-h written primarily 

 for nurserymen, it may be found useful also to purchasers of nursery 

 stock as an aid to an intellig-ent inspection of their own purchases, 

 and as a means of protection ag-ainst injury through the unnoticed 

 admission to their premises of dang-erous fung-us and insect pests. 



In making- a choice of subjects for this purpose I have had the 

 advantage of the results of several years' nursery inspection in this 

 state, and have naturally given prominence to those diseases and 

 pests commonest and most dang-erous in Illinois nurseries at the 

 present time. I have, however, further included under this discus- 

 sion a small number of both fungus and insect species hitherto un- 

 known to the nurserymen of this state, but liable to appear here at 

 any time. 



About thirty pests of the nursery have been selected for treat- 

 ment, and these are nearly equally divided between insects and 

 fungi. The most important insect species of this list are the San 

 Jose scale, the woolly aphis, the peach-borer, and the pear-leaf mite 

 causing- the "blister" of that leaf; and the most important fung-ous 

 diseases are the blig-ht of the pear and apple, the crown-g-all, the 

 root-rot, the apple-scab, and anthracnose of the raspberry and black- 

 berry. These and the less important forms of disease and insect 

 injury may be disting-uished with little difficulty by a careful study 

 of specimens in connection with the brief descriptions following-. 



Classification and Description of the Insect and Fungus 

 Pests of the Nursery most Important to the 

 Nursery Trade. 

 Injurious to the Roots. 



1. The Woolly Aphis (p. 106). 



Attacks the apple. Forms irreg-ular knots or swelling-s of 

 various sizes on the roots, most numerous on the larg-er roots and 

 near their orig-in. These outg-rowths are smooth and soft when 

 fresh, but become hard and roug-h when dry. Roots more or less 

 covered with whitish collections of small slug-g-ish insects, g-iving- 

 them a moldy look, these insects often appearing- above g-round, 

 especially upon knots, scars, or other roug-hened surfaces of trunks 

 and branches. Winters on roots as an inactive or dormant insect, 

 and on the bark as an eg-g-. 



