a 
FALL-SOWN OATS IN THE SOUTH 5 
territory the hardier and less heat-resistant winter varieties of com- 
mon oats (Avena sativa), such as Winter Turf, Culberson, and Hat- 
chett, are best adapted and can be grown successfully. South of this, 
where higher winter temperatures prevail, the less hardy but more 
heat-resistant Red Rustproof and Fulghum varieties of the red oat 
(A. byzantina) group are the only types grown or at all well adapted. 
The northward advancement of the winter-oat belt can be accom- 
plished only by discovering or developing varieties hardier than 
those now available. 
Two major factors are instrumental in winterkilling or winter 
injury of oats. These are root exposure and injury from heaving 
and injury or death of the plants from low temperatures, especially 
PINTER TURF CAG7S 
B/E IOP AICRES 
LACH LOT REPRESENTS 
L000 FCRES 
Fic. 4.—Distribution of the Winter Turf oat in 1919 and location of the two isotherms of 20° and 30° 
F. (isotherms adapted from Salmon) 
in the absence of a snow covering. Alternate freezing and thawing, 
especially in the spring, often cause severe heaving, pulling the 
plant roots from the soil and otherwise injuring and breaking the 
roots. A prolonged period of temperatures below zero, especially 
when accompanied by winds and with no snow blanket to protect 
the plants, is usually fatal to the winter-oat crop. A period of warm 
weather in winter or early spring which encourages growth and high 
moisture content of the plants, followed by freezing weather, also 
results in winterkilling or injury to oats. 
There apparently is a rather definite relationship between the 
erowth habit of the young plant and cold resistance in winter oats. 
Usually the varieties showing a decidedly prostrate or spreading habit 
in early growth are the most winter resistant. Differences in growth 
habit of the three important fall-sown oat varieties, Winter Turf, 
Red Rustproof, and Fulghum, are shown in Plate 1. A fall-sown 
oat nursery at the Arlington Experiment Farm in which certain 
varieties and strains have been injured by winterkilling is shown in 
Figure 5. 
