occurred when the winter minimum ranged between 28 and
320F, although temperatures of 25F and lower are commonly
associated with winterkill. In the Gainesville-Ocala area con-
siderable winterkilling or depletion of stand has been noted in
the early spring for many years. From 1945 through 1952 it
was observed that five or more killing frosts during the winter
with one week or more of mild temperatures (400 to 50F at
night and 60 to 80F daytime) between frosts caused severe
loss of pangolagrass plants.

Fertilizer Effect

 There is ample evidence that rate of N fertilization, espe-
cially in late summer and fall, influences the severity of winter-
killing. An experiment started in February 1954 at Gainesville
included plots sprigged to pangolagrass and given N applica-
tions of 0 to 540 pounds per acre between May 28 and Septem-
ber 23 (25). These yielded from 2,000 to 15,000 pounds of
oven-dry forage per acre in five harvests. By March 1955 it was
evident that plants receiving 447 pounds or more of N annually
had a greater tendency to resume growth during warm periods
of winter than those receiving lesser amounts. It was also ob-
served that plots receiving the high rates of N had very few
living plants. With the same fertilization practices continued
through 1955, root yields of pangolagrass plots were reduced at
N rates above 112 pounds per acre (Table 3), and plant survival
data for spring 1956 revealed the effect of increased N rates.
The phosphorus and potassium fertilization rates were variable
in this experiment, but no increase in cold resistance was ob-
tained from extra increments of either fertilizer component.

Table 3.-Effect of N rate on pangolagrass root development and winterkill
 (25).
 N/Acre Dry Roots/Acre, Living Plants/Acre,
 Annually Fall, 1953 Spring, 1956
 lb. lb.

 0 7,600 304,000
 56 6,400 256,000
 112 7,100 152,000
 224 5,600 76,000
 447 5,600 28,000
 666 3,700 20,000
 1113 2,400 4,000
 1560 1,400 0