12 
WISCONSIN HORTICULTURE 
September, 1916 
Orchard Winter Injuries 
Winter injuries to fruit trees 
-may be attributed to various 
causes but their extent is more 
largely determined in the system 
of soil management than prob- 
ably any other factor. Owing 
to the prevailing rigorous climate 
conditions, methods for lessen- 
ing the injury in its various forms 
must necessarily have become 
of vital importance to growers 
in this and neighboring states 
with similar conditions. The 
subject has been studied in its 
various phases and practical 
methods for control have been 
attempted in Wisconsin, Iowa 
and Minnesota since at least 1870 
or earlier. We have thus from 
time to time heard more or less 
about hardier varieties that are 
better adapted, of certain cover 
crops to be used under certain 
conditions, of own-rooted and 
hardy-rooted scions in nursery 
stock — but not enough of the 
proper method of soil manage- 
ment. The grower may be de- 
pendent on others in the se- 
curing of his nursery stock, but 
the care of the stock is within 
his control and upon his methods 
will depend the success of the 
orchard in- the harvest. He 
should thus become familiar with 
this problem of winter injuries — - 
and there are many forms of 
them, and recognize their cause 
and means of prevention. 
We frequently hear of blights 
and disease in trees that are 
directly traceable to the effects 
of a hard summer drouth fol- 
lowed by severe winters and 
winter killing of the trees. In 
Wisconsin we usually have dry 
summers with a long, moist 
autumn when such injury is 
most prevalent. Under such con- 
ditions conducive to little vigor 
in growth — a prolonged growing 
season and wood imperfectly ma- 
tured, with severe winters and 
high, drying winds — even the 
hardier varieties require the best 
cultural treatment to come 
through unharmed. 
Winter injuries may be classed 
for convenience under four main 
divisions according to the parts 
of the tree affected as — buds, 
roots, wood and bark. 
Bud injury is chiefly to the 
fruit buds, caused by extremes 
of cold, by permature growth 
induced during winter warm 
spells and followed by sudden 
drops in temperature. The ef- 
fects may be similar to spring 
frost injury when the whole or 
part of the crop may be killed, 
and fruit only slightly injured 
may even develop in an abnormal 
or deformed condition. Thus 
fruits are found on trees with 
otherwise perfect fruits occasion- 
ally seedless and at times core- 
less. 
Root injury occurs usually in 
very wet soils or where there is 
no ground cover of vegetation or 
snow to prevent drying out and 
deep freezing as on bare hill- 
sides. The trees will at times leaf 
out in the spring and try to de- 
velop their foliage, but, being 
unable to supply sufficient mois- 
ture as the weather grows warmer 
the leaves gradually die off. 
Injury to the wood occurs 
more or less every season and, 
evidenced in a darkening in the 
sapwood, is often difficult to 
distinguish from the ripening of 
the sapwood to form heart- 
wood. In severe cases, however, 
the darkening clear to the bark 
may be readily distinguished in 
cutting across the injured limb. 
Such injury is especially noticed 
where the wood has been poorly 
matured. If in nursery stock, the 
trees may frequently be saved 
by cutting back to the snowline 
where the wood is apt to be 
normal. 
Winter injury to the bark us- 
ually kills the cambium or grow- 
ing region in the outer wood and 
is familiar to us under the types, 
which we often indefinitely term 
as Sunscald, Crownrot and 
Cankers. 
Sunscald is shown chiefly in 
the blistering of the trunks of 
young trees and scaffold branches 
as well on larger trees, mainly on 
the sunny side with character- 
istic numerous dead and blis- 
tered areas. It may frequently 
be caused by imperfect foliage 
protection or by the reflection of 
intense sunlight in winter from 
the snow surface. Its most usual 
cause however probably lies in 
the stimulation to winter sap- 
flow on the sunny side in warm 
weather with a subsequent rapid 
freezing of the tissues. The oc- 
currence is found greater where 
the trees are less protected from 
sudden changes in air and soil 
temperatures. An adequate 
ground cover combined with 
whitewashing the exposed 
branches and trunks will usually 
effectually prevent such injury. 
Crown-rot is more prevalent 
where the union between stock 
and scion in grafting is not per- 
fect, and thus is to be looked for 
rather in younger trees. The 
tissue is more readily affected by 
severe weather conditions and 
the entrance of the rot-pro- 
ducing organisms is made doubly 
easy. As a prevention all nursery 
stock should be examined well 
before planting. 
Collar-rot and Crotch Cankers 
are more frequently found, oc- 
curring at the base of the trunk 
and at the junctures with the 
main limbs. At these parts it is 
known that the period of growth 
is continued longer than in the 
rest of the tree, the wood being 
less apt to be fully matured and 
thus more readily injured. The 
form is easily recognized in its 
