-6- 



MAGHESI UM D EFICIEIJCY 



Our experimental data shows that potash fertilization of apple trees 

 may inrluce magnesiuia deficiency symptoms. This is one more possible explanation 

 for the recent increase in the prevalence and severity of this trouble in com- 

 norcial orchards in this state. It is suggested that in orchards v/here s^Tiip- 

 toms of magnesium deficiency have been observed, the use of potassiuia in the 

 fertilizer program be discontinued, at least temporarily, 



ITliere soils are very acid (and most i^Ias sac hu setts orchard soils are), 

 v/G suggest the application of high-magnesiun limestone. The magnesiujn in lime- 

 stone is only slov/ly available. Tlie use of some soluble compound such as mag- 

 nesium sulfate (Epsom Salts) probably v/ill bo more quickly effective in correct- 

 ing magnesium deficiency, though the tir.io required may be two or more years. 

 Experiments along this line are under\/ay and it is hoped tiiat recomiiiendations 

 based on results ■•>£ this i/ork can be made vdthin a reasonable time. 



L. Southwick 



C ITRUS FERTILIZER PROGR AI'J 



A successful citrus fertilizer program consisting of three separate 

 applications per year is outlined in a recent armual report of the Florida 

 Agricultural Experiment Station. The analysis of each application is as 

 follows: Nitrogen - 3^o, phosphoric acid - 6'}o, potash - 8%, magnesium oxide - 

 2%, manganese oxide - 1%, copper oxide - l/2^^. Dolomite is used to maintain 

 the soil at pH 5.5 to 6.0, and copper-zinc sprays are applied. Thus a complete 

 fertilizer, instead of the usual N-P-K designation, looks like this: li-P-K-Mg- 

 Ivln-Cu-Zn. There is also some evidence of isolated cases of deficiency of iron 

 and boron. Other s;\Taptoms of malnutrition have occurred but have not been diag- 

 nosed. 



ilo such complicated fertilizer program is required for orchards in 

 L'lassachusetts . Ilov/ever, it is becoming increasingly evident that the program 

 may become more inclusive as time goes on. The recent diagnosis of magnesium 

 deficiency in apples and the previous findings of boron shortage, point the way 

 toward a more balanced and hence inclusive fertilizer program for Massachusetts 



°^"°'^^^^^' L. Southwick 



CjiAiraEs^_ra jnn^_i943_ apple spray chart 



The more important changes in the newly revised apple spray chart 

 for 1943 are as follov/s: (1) Lead arsenate is recoi.imended in only one of the 

 pre-blossom sprays. Previously it was included in botii the pre-pink and the 

 pink sprays. (2) Lime sulfur no longer appears among the recommended materials. 

 Instead, it appears as a substitute for wettable sulfur in one of the Notes. 

 Its use under certain weather c 'Uditions may occasionally be advisable. (o) 

 A high calcium lime appears in the list of materials for the first time. Pre- 

 viously the use of lime was discussed in one of the Notes. (4) As a means of 

 controlling a severe outbreak of red iiite, ^ne of the DIT materials is recom- 

 mended as an emergency application. 



