103 



20. The Lcaf-spoh . 



Discolored spots aud blotches on leaves, due to various fung-us 

 species and affecting- various trees. Injurious in the nursery and 

 carried over the winter either on dead leaves or on the bark of 

 twijjfs. 



WiNTHK Forms and Appearances of the Pkincipal 

 Nursery Pests. 



As nursery stock is prepared for shipment only during- the dor- 

 mant season of vegetable and insect life, the winter location and 

 condition of the pests and parasites of the nursery is of special 

 importance to both buyer and seller in the nursery trade. Only 

 those insects and fungi which pass the dormant season on the tree 

 or shrub are likely to be delivered with the stock, and the form or 

 state in which they appear at that time must determine the meth- 

 ods of inspection, of prevention, and of remedy. 



The parasites of tree and shrub which infest the root are 

 usually to be found there dormant in winter, but alive throughout 

 the year: the woolly aphis, the black peach-aphis, the crown-gall, 

 and the root-rot are examples. Those on or in the bark are either 

 the eggs of such insects as bark-lice or plant-lice; or living stages 

 of the former, like the San Jose scale; or dormant stag-es of fungus 

 parasites, such as the black-knot, the leaf-spots, and the apple- 

 scab. In or beneath the bark or wood living borers may some- 

 times be found inactive through the winter; and fastened to the 

 twigs are bunches of eggs, like those of the tent-caterpillar, the 

 bag-worm, or the tussock-moth; or partly grown insects hidden in 

 curious nests — the apple leaf-crumpler for example. 



The following synoptical descriptions of these objects will 

 serve for their identification in winter, as found on the tree. 



1. Tufts of dead leaves or similar objects fastened by webbing to 



twigs or branches. 



A tough, slender, leathery tube within the cluster of dead 

 leaves and containing a small, dark, living caterpillar. (Fig-. 16. ) 



TJic apple leaf-n'jmiplcr. 

 A grayish empty cocoon within, with a thick patch of white 

 eggs upon it which are cemented together to form a grayish 

 smooth mass. (B"'ig. 25.) Jlie titssork-moth. 



A soft bag, an inch or more in length, pointed at both ends, 

 and fastened by one to a branch or twig. Contains a mass of 

 several hundred globular eggs. (Fig-. 22.) Ihe bao-zvo)in. 



