-3- 



The set of checks (36.5) in this block v/as not extremely heavy in 1952, In 

 1951 some blocks of Mcintosh in eastern Massachusetts set over 70 fruits per 100 

 blossoming clusters. -Hov^cwer, .the dart^ ■ icdiOj^tc ^ that oven a-modoratc ovorset can 

 markedly reduce the amount cf blosacming the following 3oa3cn. I.lclntcsh v;ill 

 probably remain annual if the sot of a heavy blooming tree does not greatly exceed 

 about 25 fruits for every 100 blossoming clusters. 



Yfe suggest where Mcintosh appear to need chemical thinnJJig (set over 30 fruits 

 per 100 blossoming clusters) that it be done about 2 vreeks after petal-fall if any 

 one of the 3 hormone materials mentioned below are used. 



NA Amide (Amid-Thin) looks like a promising material for thinning Mcintosh 

 since it causes less foliage injury than NAA sprays and last year it thinned onouf^h 

 when used at the rate of 1 to 1 l/2 pints per 100 gallons 2 weeks after petal-fall. 

 However, we have had only one season's experience with it and we know Tife need 

 several seasons of experience to determine a material's good points and limitations. 

 For example, Araid-Thln may not thin enough in some years. Tliercfore, it may bu 

 well to use more than one material for thinning. A 0,2^" NAA dust applied dry on dry 

 foliage 2 weeks after calyx has given good results on Mcintosh during the past 2 years 

 in several tests. Also, NAA sprays at the- rate of 6 ounces per 100 gallons 2 weeks 

 after petal fall have been satisfactory in some orchards for thinning Mcintosh 

 (although it may thin more than the other 2 treatments mentioned and may cause some 

 foliage injury); Remember that Mcintosh is an important variety. Don't thin it 

 chemically unless thinning is definitely necessary. Also, chemical thinning involves 

 some risk so use good judgment before making treatments. For our suggestions on 

 chemical thinning mg.ny apple varieties, see our Special Circular No. 189* revised 

 March, 1953, which may be obtained from your county agent or the Pomology Department, 

 University of Massachusetts, Amlierst, Mass, 



— F. 1/V. Southwick 

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EXCESSIVE RABI VS. MGNESIUM DEFICIENCY 



Past experience has taught us to expect the amount and severity of magnesium 

 deficiency to shovj a marked increase in years which have excessive amounts of rain 

 in the early part of the growing season. The spring of 1953 can easily qualify as 

 one of excessive rainfall. Our acid soils are low in magnesium content and it is 

 readily leached by excessive rain. 



Magnesium deficiency is also generally more prevalent and severe in heavy crop 

 years. With abundant bloom in most Mcintosh blocks, we have the potential for a 

 large crop in 1953. 



Growers v:ho have not practiced an adequate dolomitic liming program for the past 

 3 or 1; years stand a good chance of having severe magnesium deficiency occurring in 

 their orchards during late summer and fall. To prevent the occurrence of magnesium 

 deficiency in such orchards, growers should be prepared to apply 3 sprays of 20 

 pounds of magnesium sulfate (epsom salts) per 100 gallons. These sprays can be 

 applied at about the time of the 1st, 2nd, ard 3rd cover sprays. The epsom salts ^ 

 may be combined with the standard fungicides and jnsocticides, but the compatibility 

 with all the new materials has not been determined. If there is any doubt as to 

 compatibility of epsom salts with the spray materials being used, the epsom salts 

 should be applied as a separate application. 



— I'J. D, Vfeeks 

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