RESPONSE TO IRRIGATION AND SOIL MOISTURE USE 

 BY MCINTOSH APPLE TREES 



William J. Lord 

 Extension Pomologist 

 Department of Horticultural Science 



The value of irrigation of Mcintosh orchards located on the better soils 

 in Massachusetts is questioned by L.F. Michelson, W.J. Lord and D.L. Field in 

 their recent Massachusetts Experiment Station Publication No. 537, 1963. 



The irrigation studies they report upon were conducted in a Mcintosh or- 

 chard from 1956 to 1962, inclusive. In this investigation, the orchard was 

 irrigated in 1957 and 1962, but a fruit growth response was obtained only in 

 1957. Even in this instance, some possible disadvantages of irrigation occurred. 

 For example, 277, of the irrigated fruit had water-core, while only 4.3% of those 

 from non-irrigated trees had the disorder in 1957. Twenty- four per cent of the 

 irrigated fruit in 1957 was 3 inches or larger in diameter, but these larger 

 apples are softer, more susceptible to bruising and are often less suitable for 

 present markets than sizes 2 1/2 and 2 3/4 inches in diameter. 



The orchard selected for the study was located on a soil with only 0.7 to 

 1.9 inch per foot moisture holding capacity. The majority of Massachusetts or- 

 chards are located on drumlins or drumloid hills with soil having an estimated 

 available moisture holding capacity of more than 1.5 inches per foot of soil to 



a depth of 3 or 4 feet or more. 



A major problem encountered in this irrigation study was the extreme varia- 

 bility of soil moisture measurements under a given tree and among adjacent trees. 

 This variability illustrates the problem of obtaining a reliable estimate of the 

 soil moisture available under apple trees. 



Moisture extraction by individual Mcintosh apple trees was studied. It was 

 found that the degree of the moisture depletion increased, as the sampling loca- 

 tion progressed toward the tree trunk. 



Those persons interested in receiving a copy of Experiment Station Publica- 

 tion 537 may do so by writing the Mailing Room, University of Massachusetts in 

 Amherst or your County Extension Service. 



All pesticide chemicals mentioned in this publication are registered and 

 cleared for the suggested uses in accordance with federal laws and regulations. 

 Chapter 727, Acts of 1960, Commonwealth of Massachusetts requires that all 

 pesticides sold in Massachusetts be registered with the Massachusetts Department 

 of Public Health. Trade names, where used for clearness, do not indicate 

 endorsement nor imply that similar products are not satisfactory. 



WARNING I MOST PESTICIDES ARE POISONOUS. READ AND FOLLOW ALL DIRECTIONS 

 AND SAFETY PRECAUTIONS ON LABELS . HANDLE CAREFULLY AND STORE OUT OF REACH OF 

 CHILDREN, PETS AND LIVESTOCK. 



