290 REPORT OF THE BOTANICAL DEPARTMENT OF THE 
related to this disease and what are the anatomic and physio- 
logic relations of stock and scion to each other: are they com- 
patible? Also, what relation to the destruction of the cortex 
and the final dying of the wood to the center of the tree, have 
the fungi often found present on the roots, crowns, trunks and 
branches of affected trees? May low temperature induce in- 
jurious enzyme-action ? 
Preventive measures.— The prophylactic measures advised in 
the main agree, but in some respects they are diametrically 
opposed. The disagreements are not to be wondered at, since 
but little work has been done in an endeavor to ascertain the 
causes under definitely controlled conditions and but little 
more upon preventive measures. The best methods of orchard 
management and the stock-scion relation required for par- 
ticular regions to reduce frost-injuries to a minimum, need yet 
to be determined, though some progress has been made in that 
direction. 
REVIEW OF LITERATURE ON FROST-INJURY TO 
FRUIT TREES. 
FROST-INJURY MOSTLY TO CROWN AND ROOTS. 
The earliest available reference on this type of frost-injury, 
in this country, is by T. J. Burrill4 The most important ideas 
in this article bearing on the question may be very briefly 
stated. If late growth occurs, as may be caused by a moist, 
warm autumn, following a drought, a severe winter will injure 
the trees mechanically by freezing the relatively large quan- 
tities of water in the cambial region. It is said that ice 
formation in the cambial region, “ together with the consequent 
shrinking of the tissues, * * * pushes off the bark.” It 
seems that the crown injury observed by Burrill occurred most 
often on the sunny side of trees. The injury was first noticed 
on account of the early yellowing of leaves in autumn. 
It is thought that cultivation and good drainage to secure a 
*Climatal destruction of orchard trees. Thirteenth Ann, Rpt, Univ, Il, 
pp. 283-93. 1886, 
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