-4- 



Dr. C. A« Peters of the Department of Chemistry at M.S.C. throws some light 

 on this problem,) 



The use of magnesium sulfate in the spray material, as a source 

 of magnesium for the orchard gives rise to new problems. If mixed with an 

 alkaline spray, white magnesium hydroxide is precipitated in voliuninoua 

 quantity. The substance, in itself, is harmless as it has a solubility 

 of less than one-tenth of one per cent. The precipitate is colored dark 

 by the lead sulfide if lime-sulfur and lead arsenate are present. The black 

 substance does not cause burning. The alkaline spray materials that bring 

 about the precipitation of magnesium hydroxide are lime or dry lime-sulfur. 

 The dry lime-sulfur is much more alkaline than the liquid, in fact, generally, 

 the liquid is nearly neutral. 



It is a question whether there is more black precipitate when al- 

 kaline substances are present or whether it just looks more abundant spread 

 out through the copious white precipitate. Anyway, the amount of the black' 

 precipitate is a measure of the amount of decomposition of lead arsenate 

 and too much decomposition may give rise to harmful products, 



~ C'. A. Peters 



EFFECT OF MOVING GRASS ON MOISTURE CONSERVATION 



To mow or not to mow the grass in an orchard, - that is the ques*- 

 tion^ Will the benefits of hand mowing around the trees, for example, 

 justify the cost? How much water, if any, is conserved when we cut a 

 growth of grass and does the stage of maturity make much difference? These 

 questions were put up to Dr, Wm. G. Colby a few days ago. His reply, which 

 for lack of space was omitted from August Fruit Notes, is as follows » 



"In order to inject some new ideas into the problem you recently raised 

 pertaining to the mowing of orchards, I submitted your memorandum to 

 Dr, V. G. Sprague at the Regional Pasture Laboratory in State College, 

 Pennsylvania, I am submitting Dr, Sprague 's reply together with a re- 

 print of some experimental work which he has done on water utilization 

 by Kentucky bluegrass and alfalfa. The results which Dr. Sprague ob- 

 tained indicate rathfer definitely that more frequent cutting of grass 

 will conserve more moisture than infrequent cutting. 



"It would seem that the problem of mowing orchards is one of balancing 

 the extra cost of frequent mowing against advantages gained in moisture 

 conservation. The answer to this problem will undoubtedly vary fran one 

 farm to another. Where orchards can be easily and quickly mowed with 

 tract ional machinery, two mowings would be more satisfactory than one» 

 Where mowing is difficult and expensive then I am inclined to feel per- 

 sonally that a single mowing would be the most desirable. If two mow- 

 ings are practiced, I suspect Dr. Sprague 's suggestion as to stage of 

 plant growth is quite accurate. But where only one mowing is practiced 

 I am inclined to think that my earlier suggestion of mowing when the 

 vegetation was fairly well along toward maturity would be satisfactory. 

 This would call for mowing a bluegrass stand in June and timothy, redtop, 

 or witch grass stand in late June or the early part of July," 



