260 REPORT OP STATE BOARD OF HORTICULTURE. 



The prevention of frosts by smudging is well known to most fruitgrowers,, 

 but for those who may have had little experience in smudging the following 

 paragraph is given. 



PREVENTION OF FROST. 



There are several different methods of preventing frost, but the most 

 practical is the smudge or smoking fire. The object of the smudge is to form 

 a smoky vapor cloud which prevents the radiation of heat from the ground 

 and thus keeps the temperature above the frost point. As no appreciable 

 amount of heat is derived from the smoke, the smudging, which prevents the 

 air and earth from losing heat, must be begun at a temperature above 

 freezing. If the work were begun at a temperature of 40° F. the ground 

 could be protected for several hours. In order that the smoke should cover 

 the ground the smudges should be placed from one to two rods apart on the 

 windward side of the spot to be protected. A good smudge can be made 

 from a i^itchy pine stump or log. In the stump vertical and horizontal auger 

 holes are bored so that they meet each other at right angles. A little coal 

 oil is poured in the vertical hole, and a match applied to oil and wood at the 

 horizontal opening. The holes act as a chimney, causing a current of air to 

 pass upward through the stump. The stump should be four feet or more in 

 height, and at least one foot in diameter, and of a pitchy character and not 

 too dry. The horizontal hole should be near the ground. If the stump is 

 large it will serve two or three nights. As it burns it may become dry and 

 begin to blaze, in which case a little water should be thrown on it; for the 

 object is to produce a smoky cloud and not to use the heat from the blaze. 

 Damp straw or manure will make a good smudge. During the season in 

 which the damaging frosts occur it is desirable to keep the stumps or straw 

 ready for use at any time, and, for this reason, the stumps are to be pre- 

 ferred, since they are not affected by the weather. 



LOW TEMPERATURE AND FROST. 



A warning of a low temperature during the night is not necessarily a pre- 

 diction of frost. Thus a warning of 40° F. near sunrise, and especially if the 

 sky were clouded, would not mean frost; while, on the other hand, the same 

 temperature at an early hour in the night, with a clear sky and no wind, 

 could be taken as a warning of frost before morning. And, in order to make 

 use of the heat remaining, smudging should be begun. These remaks can 

 only be taken for average conditions, for much depends upon local features, 

 such as elevation, slope of the land, bodies of water, and cold-air currents. 

 With a little experience and a knowledge of his ground the practical man 

 can always be on the safe side. 



In order to protect against frosts, a warning should be given when the 

 temperature has fallen not less than 8° or 10° F. above freezing. For this 

 purpose a nightwatch is often employed. Thermostats have been used for 

 the same purpose. Neither method is desirable, as the nightwatch adds to 

 the labor and expense of raising the crop, and the thermostats have not 

 proven very reliable. See Fig. 3. 



