588 RKl'OUr OF OKFICK (>K KXPKRIMKNT STATIONS. 



that hiis l)«'('ii reviewed in tliis article. Tlio woi'k with Nai'ictics and in 

 spra villi.'', and studies of the diseases and insects all'eclinLT a|)|)h's, have 

 been omitted. So niucli has heen (h)ne aion*,'' thes(> lines that, if prop- 

 erly reviewed, it would lill a volume. Attention in this article has 

 therefore hccn centered on the other (piestions i-elatinji- to apple grow- 

 in<i' which have lieeii iii\ estifj^ated by the stations. 



PERIOD OF GROWTH. 



In investii:^atin<if thegrowthof the branches of apple trees the AViscon- 

 sin Station found" that active branch j^rowth ceased one year .June 4, 

 while the followino- year it continued on many trees until ()cto})er 1. 

 Cultivation or late rain and favorable weather may induce trees to 

 make a second growth, connnencing the middle of July or later. One 

 instance is cited where, out of 325 trees that had made a second growth, 

 (3() per cent were in cultivated ground and 21.1 per cent in sod. On 

 the cultivated soil the branch gi-ovvth on many trees was as much as 

 one-half inch per da3\ Many apple grafts, top-worked, continued to 

 grow^ several weeks later than the stocks. The bark was set on many 

 of the smaller l)ranches by August 15, while on the larger trunks it 

 could still be peeled at that date. Another season the bark slipped 

 readily on all branches up to September 15, and on the larger branches 

 to September 25. Root growth was found active one season as late as 

 October (5, although no growth of twigs had occurred on an}' of the 

 trees later than 'hi\\ 1. 



In Teimessee the experiment station found'' that, as a general 

 rule, apple shoots make their principal growth in length ])efore July 1 

 and that the outermost shoots finish their growth in IcMigth sooner 

 than the lower shoots. An examination of the growth of buds on the 

 various trees showed that 50 per cent of all the buds found on Jonathan 

 in 1900 above the lown\st limb started into growth by June 30, 1901, 

 and 15 per cent had made shoots three-fourths inch long or more. 

 With York Imperial (10 per cent had started into growth and 2S per 

 cent made shoots. 



APPLE BUDS AND POLLEN. 



An extended study has been made by the Wisconsin Station of the 

 development of apple buds and the germination of apple pollen. It 

 was found that leaf buds and flower buds are not structurally distinct. 

 Every bud on the apple tree is formed as a leaf bud and everj^ bud on 

 the tree has the power to become a flower bud. Leaf and flower buds 

 are, in a measure, interchangeable. By pruning away the branch 

 immediatel}' above a flower bud it may be converted into a leaf bud, 



a Wisconsin Sta. Rpt. 1900, p. 3. 



6 Tennessee Sta. Bui., Vol. XIV, No. 4. 



