-8- 



CORRECTION OF MAGNESIUM DEFICIENCY 



Magnesium deficiency is rather widespread in apple orchards. In 

 some oases ^ definite symptoms such as leaf scorch, early defoliation and 

 excessive preharvest drop have been observed. In others, clear-cut symptoms 

 have not been noticed. It is probably true that many orchard soils in the 

 Northeast are close to the deficiency level for many plants, including apple 

 trees. For this reason, the general orchard use of high magnesium limestone 

 is recommended, except where the soil acidity is already up to pH 6, or above. 

 One other recommendation that could be follov/ed rather generally is the in- 

 clusion of Epsom salts in one spray application. The use of 15 pounds of 

 Epsom saltis in either the First or Second Cover spray might help to tide 

 trees over a slight magnesium shortage situation. For definitely deficient 

 orchards, further measures are advisedi The above recommendations refer to 

 "borderline" cases, where definite deficiency symptoms have not yet appeared. 



— Lav/renoe Sbuthwick 



ORCHARD HEATING 



The old idea that a smudge or smoke screen will ward off a frost 

 has boen disproved. Frost damage in an orchard is prevented only by actually 

 raising the temperature of the air above the danger point. Many small fires, 

 viell distributed, are much more effective than a fev/ large ones which might 

 merely serve to set up heavy convection currents and thus bring in a flood 

 of cold air from the surrounding country. One large fire, as for example 

 a burning brush pile alongside the orchard, is likely to be of little if any 

 benefit. 



Only an occasional grower in Massachusetts will probably find it 

 possible to equip himself v;ith the necessary containers and fuel for orchard 

 heating this spring. As a matter of insurance, in case the temperature drops 

 only a degree or two below the critical point, even as few as 10 or 15 con- 

 tainers per acre may be worthwhile. One grower who has done considerable 

 orchard heating believes that approximately 25 containers per acre are neces- 

 sary Vfhere a severe freeze is involved. He has used paint pails holding two 

 or more gallons and has actually raised the temperature of the orchard air 

 as much as 6 degrees above that of the surrounding territory. Ordinary fuel 

 oil was usQd» Y/aste crankcase oil has the disadvantage of boiling over be- 

 cause of its water oontont. Anyone who plans to try orchard heating this 

 year must of necessity provide himself with one or more strategically lo- 

 cated thermometers which are accurate within a degree at least. The next 

 item of importance is to make sure that the heaters are lighted shortly be- 

 fore the temperature drops to the danger point. 



PENICILLI N - LIKE SU BSTAI^[CE FOUND IN LEAVES AND FRUITS . Research workers at 

 Michigan "State College have discovered" germ-killing substances in the fruits 

 of blueberry, currant, mountain ash said honeysuckle, and in the leaves of 

 the Scotch thistle, mullein and peony. Negative results were obtained from 

 horseradish, turnip, and cabbage. These discoveries suggest that the Indian 

 medicine man and other users of plant extracts, poultices, etc. may be ahead 

 of their time. 



