squares in 52 minutes. 



Various other methods of laying the plastic are being tried by growers. 

 One grower placed hay over the plastic. In another instance, short pieces of 

 wire were bent U-shape and thrust through the plastic to keep it in place. 



•/< i< -k i< ■k it 



FACTORS AFFECTING NUTRIENT CONTENT OF APPLE FOLIAGE 



W.D. Weeks 

 Department of Horticultural Science 



Crop size can have a considerable effect on the quantity of several 

 elements in apple foliage. Leaves from a tree with a large crop will contain 

 more nitrogen and less potassium than leaves from a tree with a light crop. 

 Leaves from a light crop tree may have a leaf nitrogen which is .2 and .3 per 

 cent lower than the same tree when it has a full crop. Differences in leaf 

 potassium as great as .4 per cent may occur between heavy and light crop years. 

 Calcium follows the same trend as nitrogen and exhibits about the same differ- 

 ence as nitrogen in leaf content between the light and heavy crop year. Leaf 

 magnesium is slightly higher in a heavy crop than in a light crop year. Crop 

 size has little, if any, effect on leaf phosphorus. 



The relative amount of one element in relation to another may effect the 

 mineral content of the leaf. For example, leaves which are relatively high in 

 nitrogen tend to have lower levels of potassium and phosphorus and higher 

 levels of magnesium and calcium than leaves from trees which have a low to 

 medium level of nitrogen. High levels of potassium may depress leaf magnesium 

 and calcium, particularly if the soil supply of magnesium and calcium are low. 

 However, moderate levels of potassium do not seriously depress magnesium where 

 there is an adequate supply of magnesium. 



Another factor which may influence the leaf content of some elements is 

 soil moisture or rainfall. Leaf potassium is generally lower in dry growing 

 seasons than in years with adequate soil moisture. Magnesium is generally 

 lower in years which have above normal rainfall during the early part of the 

 growing season. The magnitude of the change in leaf content caused by seasonal 

 rainfall will depend upon the wetness or dryness of the season and the supply 

 of nutrients in the soil. Soil moisture extremes, either wet or dry, which 

 prevent the development of new roots could conceivably reduce the leaf content 

 of essential elements. 



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