April, '21] DUSTING DISCUSSION 237 



emergence of the beetles, whereas dry weather effects the destruction of a 

 great many of them in the soil. Rainy weather furthermore keeps 

 down a number of important parasites. 



Under the hot humid conditions in Georgia, the plum curculio has 

 developed apparently a partial second generation, and it is this supposed 

 second generation that is responsible for the large amount of ripe, 

 wormy peaches. 



The campaign against the curculio in that section should be to destroy 

 beetles of the first generation by all means possible. Growers will 

 doubtless bum the areas around the orchards, destroy plum thickets, 

 and thus kill the insect in hibernation. They will spray three or four 

 times, collect fallen fruit under the trees that contain the grubs, and 

 perhaps some of them will resort to the old "jarring" method which was 

 discarded with the advent of sprays. 



Mr. McClintock: Do you think that is practical for the Georgia 

 orchards where they have thirty or forty thousand trees' 



Mr. a. L. Quaintance : It is a question of man power. They have 

 been doing operations on a large scale. The negro help is becoming 

 abundant. They will do the best they can. 



That is the reason that dusting has had so much favor and has been 

 so much in vogue in that region. That is one reason why it is fortunate 

 that dusting has a place in peach growing. Conditions are much 

 improved and m.any of the orchardists are in condition and prepared to 

 carry out extensive programs of curculio repression. 



Mr. Y. I. Safro: Just to try to settle some misunderstanding that 

 may yet remain as regards this nicotine discussion, I want to say that 

 both Professor Moore and Professor Ruth are correct. Nicotine sul- 

 phate is not volatile, but it doesn't remain nicotine sulphate long under 

 ordinary conditions. The ordinary water, as it is used throughout the 

 United States, has enough elements in it to break dowm nicotine sul- 

 phate, and what you get when it finally reaches the tree is free nicotine 

 which is volatile, so both of these gentlemen are correct. Dr. Moore 

 has an uncanny habit of explaining things that have puzzled us for a 

 long time and made the statement that he wouldn't be surprised to 

 learn that nicotine with sulphur was more effective than nicotine with 

 other materials. That is so, as the result of experiments that have been 

 carried on the past year in three different states. We never could ex- 

 plain just why it was so until Dr. Moore offered the explanation; we 

 were at sea, but it is true. A weaker solution, or rather a weaker 

 nicotine content in a dust in which the sulphur is a carrier seqns to be 

 more effective than one in which the clay is a carrier. This is merely a 

 nicotine discussion; I am not recom-mending any dust. 



