Grove Heating 
Rolland E. Stevens 
Mr. President, Ladies and Gentlemen : 
The object of grove heating, or smudg¬ 
ing, as it is popularly termed, is to keep 
the temperature in the grove above the 
danger point. This point is not an ab¬ 
solutely fixed one, by any means. There 
are times and conditions when fruit will 
freeze at 30 degrees Fahrenheit, ana 
other times it will not freeze with the 
thermometer at 28. Some growers claim 
that an orange will stand 26 degrees for 
three hours; as to this I am not prepared 
to say. If it is a possible thing, I don’t 
ever expect to let the temperature get 
to 26 degrees when there is either fruit 
or bloom on the trees. A dormant orange 
tree will stand remarkably low tempera¬ 
tures. Personally I think that in Decem¬ 
ber or the early part of January, if the 
trees are in a dormant condition, they 
could stand 15 or possibly 10 degrees 
above zero with little or no damage; the 
fruit, however, will not stand any such 
temperatures as these. The danger mark 
must be decided by each man for himself, 
and when he has done so he must use 
whatever means he has for protection ac¬ 
cordingly. It is better to be safe than 
sorry, and while it is not advisable to 
burn up a large quantity of oil needlesssly, 
still it is better to burn the oil and save 
the fruit or trees, than to save a few gal¬ 
lons of oil per acre and lose a car of 
fruit per acre or several years’ growth off 
the trees. It must also be kept in mind 
that it is much easier to hold the tem¬ 
perature at any given point than it is to 
raise it to that point after, it has gone 
below. 
There are two distinct methods of pro¬ 
tecting a grove from frost. I shall di¬ 
vide these as follows: First, overhead 
protection, which includes sprinkling sys¬ 
tems of all kinds, with which many of 
you are familiar,—the so-called ‘‘over¬ 
head irrigation systems.” These will keep 
off a frost and will raise the temperature 
a little, in all probability, as the water 
here in Florida will be some warmer than 
the air. It will also help the fruit that 
has been frozen on the trees to turn on an 
overhead system and thoroughly soak out 
the fruit and foliage. The damage will 
be much less than if the sun came out on 
the fruit and trees when they were cov¬ 
ered with frost. Another overhead sys¬ 
tem which has been used in a few isolated 
instances, is the use of sheds. I shall not 
dwell on this as the cost of installation 
and up-keep is practically out of the ques¬ 
tion. 
Second, protection by fires: There are 
three classes of fuel available for fires— 
wood, coal and oil. Wood, while perhaps 
cheaper than the other two, has several 
disadvantages. It takes too long to build 
a large number of fires; it is impossible 
to regulate the fires -very close; and is 
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