MEXICAN" BEAN BEETLE IN THE SOUTHEAST. 47 



USE OF SPRAYED BEANS AS FOOD. 



For two seasons beans treated with arsenicals have been analyzed 

 for arsenical deposits. In no case has the amount of arsenic per 

 quart of green snap beans as picked approached the point where 

 there is any danger whatever from consumption of even this amount. 

 Snap beans which have been treated should be washed in two changes 

 of clear water before marketing to safeguard against any difficulty 

 from this source. In accordance with ordinary cleanliness, beans 

 should be thoroughly washed before cooking. There is not the 

 remotest danger from dried beans. Bean- vine hay which has been 

 treated with arsenicals must not be fed to stock. 



COST OF TREATMENT. 



Computations of the cost of treating an acre of beans, from records 

 obtained on the experimental plats, give results as follows: Spray- 

 ing costs from $4 to $8 per acre, depending on the costs of arsenicals 

 and type of machine used; dusting costs from $4.50 to $12 per acre, 

 depending chiefly on the prices of arsenicals and the type of machine 

 used. These figures are based on four treatments of bush beans 

 drilled in rows 3 feet apart. 



In these calculations, man labor is figured at 20 cents per hour 

 and horse labor at 10 cents per hour. Where labor is higher, 

 calculations may be made to suit conditions. From 4 to 8 hours 

 are required to spray an acre of bush beans with a small hand sprayer, 

 depending on the size of the beans. The wheelbarrow sprayer 

 mounted on a slide and drawn by a horse requires the time of two 

 men and one horse for 3 hours. The power sprayer requires two 

 men and two horses for one-half hour each. The hand duster 

 requires one man for 2\ hours. The power or traction duster requires 

 25 minutes time of one man and two horses, but this may be reduced 

 on large acreages. Time of refilling machines is included in the above. 



DISCUSSION OF ARTIFICIAL CONTROL. 



Sprays, compared with dusts, have given consistently superior 

 results for two seasons. Much of the difficulty with dusts is traceable 

 to the manipulation of dusting machinery, which is not at present 

 as suitable for treating the under surfaces of leaves on low crops as 

 spraying machinery. 



With the perfection of dusting machinery and methods of applica- 

 tion, dusting will probably become a more desirable farm practice 

 in many cases than spraying. Where growers are equipped with 

 machinery for spraying, and are so situated that water can be 

 easily obtained, better results will be obtained by this method. 

 Spraying is not so dependent on weather conditions as dusting, since 

 the adhesion of the spray to the leaf is greater and the material is 

 not washed off the leaves by rains as easily as is the case with the 

 dust. Again, spraying can be done under atmospheric conditions 

 which are unsuitable for dusting. In many cases this makes it pos- 

 sible to obtain better control with one or two fewer applications of 

 sprays than of dusts. The amount of the arsenical required per acre 

 is of course much less with spraying than with dusting, and in view 

 of the increasing price of arsenicals this factor is becoming more and 

 more important. 



