70 AGRICULTURE OF MAINE. 



thinning is the most important means of increasing the size 

 of the fruit. Below it, the size can usually be markedly af- 

 fected by moisture supply, cultural methods, manure, and 

 possibly by fertilizers, — especially those rich in potash. The 

 latter factors may also cooperate in such a way as to materially 

 raise the critical point. In general, however, proper thinning 

 and moisture conservation are the most important means of 

 improving fruit size. 



The Control of Fruit Color. — In Table V, it will be observed 

 that none of the fertilizer treatments has resulted in any 

 m.arked improvement in color. Slight and irregular benefits 

 are shown by potash and by some of the phosphate applica- 

 tions, but nothing of any importance. The same is true of 

 iron applications, so far as experimental evidence is concerned. 



These facts again lead up to the general propositions that 

 color in apples cannot be materially increased by fertilizer 

 applications, and that their red colors are essentially dependent 

 upon maturity and sunlight. Conditions that tend to increase 

 one or both of the latter factors, such as late picking, open 

 pruning, light soils and sod culture, tend to increase the red 

 color. Opposite conditions decrease it. 



These propositions make it clear why the nitrates and ma- 

 nure apparently injure color. It is simply done by retarding 

 m'aturity and diminishing the available sunlight, as a result of 

 the increased density of foliage. To determine the truth of 

 this, in 1911 we left the fruit on the nitrate plats in the John- 

 ston orchard until it had reached approximately the same de- 

 gree of maturity as that attained by the checks when their 

 fruit had to be picked on account of dropping. The delay 

 required was fully three weeks, — from September 29th to 

 October 19th, and even then the later fruit was picked with 

 much more difficulty than that on the checks, besides showing 

 a much lower percentage of fruits dropped. The amount of 

 color on the nitrate plats at the later date was actually greater 

 by 10 per cent than that shown on the checks at the time of 

 picking. 



The occasional marked increase that sometimes occurs in 

 color as a result of spraying is largely explainable on similar 

 grounds. The spray reduces the worminess and thus enables 



