Bul. 1169, U. S. Dept. of Agriculture. PRATE LHe 
IMPROPER WAYS OF APPLYING PARADICHLOROBENZENE. 
1. The crystal ring is too close to the tree trunk. It should be at least 1 inch away. 2. The crystal 
ring is too far from the tree trunk for good results. 3. The soil level should have been raised around 
this tree before applying the crystals, as there are borers at work above the present soil level. No 
borers will be kiiled above the crystal ring, as the gas is heavier than air. 
