EXPERIMENT STATION WORK WITH APPLES. 539 



and In' rinoiiio- u ln-aiich just ])olow a leaf Imd it may be converted 

 into a Howei- Imd. Factors which tend to the foi'niation of flower 

 buds are any restriction of prepared food in the Inariches, such as is 

 caused hy rino-ino- or a wrinkliu*;- of the bark foi-nied by the union of 

 the fruit spur with the branch which supports it. Dry weather is also 

 conducive to the formation of flower buds, since durintv such drv 

 periods evaporation through the leaves is rapid and sap becomes con- 

 centrated and rich in prepared food. Flower buds are then formed in 

 portions of the tree where there inaj' be no restrictions to the move- 

 ment of the sap, as at the end of young shoots. Whenever the water 

 supply is increased the tendency is to wood grow'th and the formation 

 of leaf buds. A decrease in water supply tends to make flower buds. 

 A noi-mal growth is accompanied ])y normal formation of flowers. 

 When the fruit spurs of a healthy tree push into growth or sap 

 sprouts start freely from the old wood, growth is abnormal and fruit 

 production is postponed.'* 



The flrst clear evidence of flower ])uds on the apple tree was found 

 one season .Tune 80.'' Another season flower l)uds for the most part 

 were formed })etween August 1 and September B.'" Flow'er buds do 

 not usually form until active wood growth for the season stops. At 

 that time they may begin and continue until cold weather sets in. 

 The same fruit spur has been found to fruit annually in some instances, 

 instead of biennially, as has sometimes been claimed. In the flower 

 buds the calyx and receptacle are first to appear, next the stamens and 

 petals, which are apparently outgrowths of the calyx or receptacle, 

 and finally the pistils, which are extremely slow in developing. The 

 observations indicate that flower buds seldom or never revert to leaf 

 buds, though the}' may not develop into flowers for several seasons. 

 If heavily shaded they may never bloom; l)ut during very favorable 

 seasons for the formation of flowers all the 1-year old, 2-year old, and 

 3-year old flower buds, many older ])uds, and some buds formed during 

 the j'ear, may form eml)r3'o flowers. This explains why an excessive 

 fruit crop is always followed by a scanty one. "There are no reserve 

 buds. Only the buds formed the preceding season are developed, and 

 the draft on the tree necessary to develop so many apples prevents 

 many of these from forming flowers, even if they are of the annual 

 flowei'ing variet}'."" 



While the production of flower buds on the apple tree is largely 

 controlled t)y climatic conditions, a numlier of other factors also enter 

 in over which the orchardist has control. The t(Mni)erature may be 

 moditied by planting on the north or noitheastern slopes. Early 



"Ainer. (ianl., 22 (Ii»()l), No. 332, p. 330. 



''WiscniiHin Sta. Kpt. ISOO, j.. 2Sf>. 

 '•Wisconsin Stu. Hpt. IKOl, p. 304. 



