IOO WEEDS OF THE FARM AND GARDEN 



eight gallons of water. This is also a poison. Use with 

 caution. 



Iron Sulphate. For a number of years experiments 

 have been conducted by a number of experiment stations 

 with reference to the extermination of weeds by this 

 chemical. It has been found at the Iowa Experiment 

 Station that a number of weeds like dandelion, dooryard 

 knotgrass, purslane, yarrow, sorrel, large ragweed, hedge 

 mustard, sour dock, smartweed, mustard, velvet leaf, 

 small ragweed, lamb's quarter, pepper grass, sow thistle, 

 bull thistle, wild carrot, pigweed, shepherd's purse, and 

 spurge can be destroyed by this substance. Bolley finds 

 that it is not effective on pennycress and hares' ear 

 mustard. The grasses are resistant. This substance 

 should be used at the rate of 100 pounds to a barrel of 

 water. A dust spray has also been used ; it is effective 

 when there is sufficient dew on the plants. 



In order to make the spraying effective, however, the 

 application should be made sometime before the mustard 

 or other weeds are in bloom. It is advisable to begin 

 spraying in a grain field when the mustard is from 6 to 12 

 inches in height. Bolley puts it third to fifth leaf. The 

 spray should be evenly spread over the leaves on a 

 quiet day with no rain for two or three days. Damp 

 weather is effective if sunshine follows. It is better to 

 use a large machine having a capacity of 160 gallons, and 

 if the ground is not too soft two horses can pull the ma- 

 chine readily. The machine should have wide tires. The 

 trouble, as Bolley well says, is because nozzles and 

 machines are not efficient. 



The cost of spraying is approximately $1.25 per acre 

 and the iron sulphate can be had approximately from 

 $1.00 to $1.15 per 100 pounds in the northern Mississippi 

 valley. 



Professor Selby briefly sums up the matter of spraying, 

 as follows : 



