6 BULLETIN 208, U. S. DEPARTMENT OF AGRICULTURE. 



In the last column of Table I the annual yield has been omitted in 

 those rows harvested during the growing season, for reasons already 

 stated. An average of the others gives a yield for the portion har- 

 vested during the crop's dormant season of 40.463 tons per acre per 

 annum. Omitting rows 20 to 22, inclusive (which is justifiable on 

 account of the poor stand), the average yield per acre per annum is 

 43.557 tons. It should be borne in mind that a part of this is aver- 

 aged for two years' growth and a part for a three-year period. In 

 other words, rows 20 to 27 were harvested after two seasons' growth 

 and rows 35 to 48 after they had attained the growth of three seasons. 



The species of prickly pear grown in these experiments were a 

 mixture of the three discussed on page 3, but Opuntia gommei and 

 Opuntia cyanella greatly predominated. The quantity of the other 

 species grown was negligible. 



In addition to what has been said regarding the handling of this 

 plantation, it should be stated that no cultivating at all was done 

 after the' second season. Cuttings were set in this planting, as in 

 the other, in 8-foot rows, no attempt being made to space them 

 exactly. Under these conditions, the plants had bridged over the 

 8-foot rows at the close of the second year's growth to such an extent 

 that animals could not pass through and cultivation had to be 

 abandoned. (PL II, fig. 1.) 



CONDITION OF THE PLANTATION. 



The condition of the plantation was first class during the entire 

 period up to late in the winter of 1913. At this time the common 

 fungous diseases of the region began to be alarmingly prevalent; 

 indeed, so much material had to be discarded in feeding that accurate 

 estimates of yields could not be secured after the first of March. 

 The cause of this condition was not difficult to interpret. The season 

 of 1912-13 had an abnormal rainfall and a winter temperature with 

 a high minimum. Weeds and grass grew thick among the plants 

 and remained green for the most part during the entire winter. The 

 pear itself had grown into an impenetrable thicket, furnishing the 

 best conditions possible for the development of the fungi. 



In this region.it seems as though the age of the plantation when 

 harvested will have to be considered more than in any other in which we 

 have worked, because of the liability of the development of various 

 diseases when the thicket becomes so dense as to prevent the aeration 

 of the inner delicate vegetative parts. It is possible that when grown 

 under usual conditions it will be necessary, in order to secure the best 

 results, to harvest at from 18 to 36 months rather than let the crop 

 stand for longer periods, as is possible in the San Antonio region or 

 farther inland in general. The common diseased condition of the 

 prickly pear in the brush about Brownsville points to its suscepti- 



