70 CIRCULAR 270, U.S. DEPARTMENT OF AGRICULTURE 



NICOTINE 



Nicotine is a very effective contact insecticide for sucking insects, 

 as it not only destroys insects by coming in direct contact with them 

 but also acts as a fumigant in hot weather, killing insects that do not 

 actually come in contact with the spray. This fumigating action is 

 undoubtedly limited to a very short distance, possibly only a fraction 

 of an inch. For this reason it is advisable to spray with nicotine on 

 calm days when the temperature is above 80° F., if possible, and under 

 such conditions the quantity of nicotine recommended for cold weather 

 may be reduced. Nicotine is sold in the form of free nicotine and also 

 in the form of nicotine sulphate (40 percent nicotine), the latter being 

 employed chiefly for orchard spraying. Homemade decoctions are 

 likely to be unreliable. If nicotine sulphate is used alone, 2 or 3 

 pounds of soap dissolved in water or 1 pound of casein spreader should 

 be added to each 100 gallons of water, to cause the mixture to spread 

 better and penetrate any waxy covering of the insects. The soap 

 should be omitted if the nicotine is added to other insecticides, but 

 the spreader may be used. 



PYRETHRUM 



Pyrethrum is finding some use as a contact insecticide. It has 

 little fumigating action, and is thus likely to be less effective than 

 nicotine in hot weather, but in cool weather it is very useful. It 

 should be diluted according to the manufacturer's directions. 



SPREADERS AND STICKERS 



Some sprays have a tendency to collect in drops and roll off the fruit 

 or foliage, and some are easily washed off by rains. A number of 

 materials may be added to insecticides to overcome these difriculties. 

 Various soaps have been used as spreaders and are very useful in 

 nicotine sprays ; but soaps are incompatible with lime-sulphur solution 

 and should not be used with it. Also, when used with standard lead 

 arsenate they have a tendency to produce free arsenic, which may burn 

 the foliage or fruit ; since soap also causes the lead arsenate to spread 

 out too thinly, these two materials should not be used together. 

 Another spreader that has been used very commonly is a mixture of 

 casein and lime, commonly known as casein spreader or calcium 

 casemate. This is very useful with nicotine or lime-sulphur sprays 

 and in a combination of lead arsenate and lime-sulphur or lead arsen- 

 ate and oil emulsion. Its use with lead arsenate alone, however, is of 

 doubtful value, as it has a tendency to spread the insecticide too thinly. 

 There are other spreaders containing protein that may not have this 

 disadvantage. Fish oil is a very effective sticker for lead arsenate and 

 other poisons, and some fish oils, particularly certain herring oils, 

 also tend to spread the insecticide more uniformly. 



SPRAYING SCHEDULES 



In the Pacific Northwest extensive spraying schedules for insect 

 control are required only for pears and apples. Ordinarily other fruit 

 trees should be sprayed while dormant, and at other times only if 

 insects become troublesome, as explained in the sections of this circu- 

 lar dealing with the control of the various insects. Apple and pear 

 trees should also be sprayed while dormant, as a rule, for the control 

 of scale insects, red spiders, and other pests that may be on the trees 



