STRAWBERRY PESTS 



1943 



eggs upon the lice, hatching into a grub 

 which feeds within the body of its host, 

 eventually emerging as an adult through 

 a large circular opening in the body of 

 the louse. These two enemies dispose of 

 considerable numbers of the pests, but 

 not enough usually to constitute an im- 

 portant factor in control. 



Control 



The first consideration in prevention is 

 clean plants on clean land. If land has 

 become infected, rotation should be prac- 

 ticed with crops requiring constant cul- 

 tivation. If coin and melons are the 

 rotation crops, care should be taken that 

 they are not infested with root lice, for 

 while the strawberry root louse is not 

 found upon these plants they might spend 

 a season there if the ground is badly in- 

 fested with them to begin with. 



When plants are purchased from a nurs- 

 ery the utmost care should be taken that 

 they are clean of all lice. If none are in- 

 troduced of course none will appear. The 

 best plan is to buy from a region where 

 as yet no root lice have appeared. In 

 this way it may be possible to keep them 

 out of new territor.v. Compel the nurs- 

 ery man to guarantee freedom from pests. 

 If it is impossible to get plants free from 

 lice they may be disinfected. 



The following discussion of a method of 

 disinfecting strawberry plants is repro- 

 duced from Bulletin 49, Delaware Experi- 

 ment Station, by E. Dwight Sanderson: 



Disiiifecfioii of Plants 



All methods of disinfection must be ap- 

 plied after the aphis eggs have hatched 

 (first week in April), as none of them 

 have been found to kill the eggs. Inas- 

 much as the weather conditions upon 

 which depends the time of planting also 

 determine the time of hatching of the 

 eggs, but little inconvenience will usual- 

 ly be. experienced by waiting for all the 

 eggs to hatch. The plants will need to be 

 carefully gone over and the eggs exam- 

 ined with a magnifying glass to see that 

 they have hatched before disinfecting can 

 safely be commenced. 



1. Dippinie; 



In dipping plants they should be 



thoroughly submerged, as a few lice will 

 be found both on the leaves and roots at 

 almost any season of the year. 



Kerosene Emulsion 



Dr. C. M. Weed states that he success- 

 fully disinfected plants in Ohio by dipping 

 in dilute keiosene emulsion. This may be 

 made according to the following formu- 

 la: 



Kerosene, two gallons; whale-oil soap 

 (or one quart soft soap), one to two 

 pounds: water, one gallon. Dissolve the 

 soa]) in the water by boiling, and add, 

 boiling hot, away from the fire, to the 

 kerosene. Agitate violently for five min- 

 utes by pumping the liquid back upon It- 

 self with a force pump and direct-dis- 

 charge nozzle throwing a strong stream. 

 The mixture will have increased about 

 one-third in bulk and have become about 

 the consistency of cream. Well made, the 

 emulsion should keep indefinitely, and 

 should be diluted only as wanted for use. 

 Dilute this with 10 to 15 parts of water. 

 The plants should not be left in this 

 emulsion more than two or three minutes 

 and should then be well washed in fresh 

 water. 



2. Funii^fation with Hydrocyanic Acid 

 Gils 



Though dipping in an insecticide will 

 undoubtedly kill most of the aphids, fimri- 

 gation by means of hydrocyanic acid gas 

 is much quicker, less work, and a more 

 certain and complete remedy. It should 

 always be remembered that it is a most 

 poisonous gas and should be used with 

 caution. 



A. Apparatus 



The only apparatus needed is a fair- 

 sized air-tight box. This box is 2x2x2% 

 feet, without a bottom, made of two 

 thicknesses of matched wainscoting with 

 buildmg paper between; the cover closes 

 upon a rabbet the depth of the thickness 

 of the material and lined with felt; a 

 small door about 6x6 inches is placed at 

 the lower corner and similarly fitted so 

 as to close on felt; four or five frames cov- 

 ered with wire netting rest upon the 

 cleats, the lower one being about three or 

 four inches above the ground and extend- 



