144 MASS. EXPERIMENT STATION BULLETIN 177. 



sprayer or similar apparatus, but numerous combinations of rods and 

 nozzles may be made to increase the spraying area or the number of rows 

 treated at one time. In the case of traction sprayers or other direct row- 

 spraying apparatus the common inverted T method is ordinarily used 

 with two nozzles attached to throw spray in opposite directions, so that 

 two rows may be treated from each T. By attaching several T's to the 

 main cross rod, so that the T's come between the rows, a number of rows 

 may be sprayed simultaneously. It is essential with such apparatus that 

 the T's be made sufficiently long and the nozzles attached at the proper 

 angle to thoroughly drench the underside of the foliage. Work with such 

 apparatus must be done slowly if satisfactory results are to be expected. 

 Some growers have adopted an arrangement with traction sprayers 

 whereby a cross piece, located a short distance in front of the nozzles, 

 tips over the plants. The nozzles are directed forward and downward so 

 that, theoretically, while the plants are thus tipped over, the underside of 

 the leaves are covered with the spray. Not only is the efficiency of this 

 method open to doubt, but the effect upon the plants of such treatment is 

 worthy of consideration. 



A nozzle giving a fine mist spray is essential. The disk and Vermorel 

 are two types of nozzles well adapted for the work. The disk nozzle 

 must be of the angle form, which gives a suitable underspray at a right 

 angle to the rod, and covers a fairly large area, being on this account pref- 

 erable to the Vermorel nozzle. The Vermorel nozzle cannot be purchased 

 in the angle form, but a 45° elbow can be obtained or a bend made in the 

 extension rod to overcome this difficulty. It is fairly well adapted for 

 use with a knapsack or compressed-air pump. 



Where a considerable length of hose is needed it is desirable to have this 

 as light as possible in order to faciUtate handUng among the rows with 

 the least possible injury to the plants. One-fourth inch Meruco tubing 

 has been found highly satisfactory for this purpose, especially for the 

 leading hose. Attachments for this tubing to rubber or cotton hose of 

 larger size can be readily obtained. Long-tail hose couplings will also be 

 found advantageous in preventing a "blow-out" where pressure of any 

 amount is used. 



Summary of Control Measures. 



1. Potato plant lice can be readily controlled by the use of a contact 

 insecticide of "Black Leaf 40" or similar nicotine preparation at the rate 

 of 1 part of this material to 800 parts water, with the addition of com- 

 mon laundry soap, dissolved in boiling water, at the rate of 2 pounds 

 (liquid or soft soap, 1 quart) to 50 gallons of the diluted "Black Leaf 40" 

 solution. The formula in practical terms is given on an earlier page. 



Fish-oil or whale-oil soap at the rate of 1 pound to 6 gallons of water is 

 about equally as effective, but is less desirable on account of the extra 

 time and bother involved in dissolving larger quantities of soap. 



"Black Leaf 40" can be combined safely with Pyrox, Bordo-lead, Bor- 



