RELATION OF STAND TO YIELD IN HOPS. 29 



The importance of replanting and the success with which it has 

 been carried out on the acre under observation may readily be 

 judged from Table II. In 1910 less attention was bestowed upon 

 the replanting than in the two succeeding years, with very obvious 

 results. Were it not for the continuous dying out of the lulls an 

 almost perfect stand could readily be attained. It is important to 

 note that each year there was added to the list of missing hills a 

 number that previously had been productive. In fact, it frequently 

 occurs that a hill which has been producing heavily for several years 

 suddenly becomes "missing," Of the 110 new missing lulls recorded 

 in 1912 the average yield for the previous year was 10.2 pounds 

 green weight, and 56 of these lulls had each given a high yield in the 

 years 1909 to 1911, inclusive. 



Out of the entire number of hills on this acre only 1 has been 

 missing for the whole period of four years, 4 have been missing for 

 three consecutive years, and 45 for two years in succession. Of the 

 56 lulls missing in 1909 only 6 were still missing in 1912. Altogether, 

 193 different hills have been missing on this acre during the past 

 four years, winch would have necessitated the replanting of more 

 than 20 per cent of the entire number of hills if a perfect stand were 

 to be maintained. The fact that new missing hills occur each year, 

 many of which have previously been highly productive for several 

 years, strongly suggests that the average length of life of the culti- 

 vated hop plant may be less than is popularly supposed. Cases are 

 known where it is claimed that individual plants have given a fair 

 yield each year for 30 years, but many growers agree that, with a 

 newly planted yard, after three or four crops have been harvested 

 the hills begin to die out to a greater or less extent. Positive con- 

 clusions on this point, however, can not be drawn from the data in 

 hand, since the period covered by the observations is entirely too 

 short to be more than suggestive. 



VARIATION IN PRODUCTIVE STAND. 



A large part of the variation in productive stand is caused by the 

 occurrence of hills having vines producing no hops. Such hills pre- 

 sent a greater problem than those which are missing, since many of 

 them if left undisturbed produce a good crop the following year and 

 digging them out and setting new plants might result in loss rather 

 than gain. Each year a few of the replants fail to bear hops; others 

 of the hills are probably unproductive through loss of vigor, since a 

 number are dead the following year, and some vigorous and normally 

 productive hills through some accident fail to yield a crop. How 

 these various classes among the hills having vines but no hops are 

 distributed from year to year is shown in Table III. 



[Cir. 112] 



