PINK BOLLWORM OF COTTON IN MEXICO. 



31 



Willcox (7) states that there is marked reduction in the quantity 

 of oil produced and that the quality is of an inferior grade. 



NONPICKABLE COTTON. 



It is in this class that the major portion of the gross damage 

 occurs. As has been previously stated, there is a certain percentage of 

 the cotton damaged to such an extent as to render it unfit for picking. 

 This cotton naturally is left on the plants after the pickings are 

 finished. 



An effort has been made to determine the exact portion of the crop 

 that is affected in this manner. By selecting what appeared to be 

 average-sized plants (according to the number of bolls per plant, 

 etc.) in fields of several different average plantations, about 3,000 

 plants were examined after the cotton had been picked. These 

 plants were examined individually, the total number of bolls on 

 each plant and total number of bolls lost on each plant due to attack 

 of the pink bollworm being recorded. In counting the total number 

 of bolls an empty burr was counted as a boll, and in the calculations 

 has the weight of a perfectly sound boll. 



In counting "bolls lost," only bolls or portions of bolls which 

 showed plainly that their damage was caused by the pink bollworm were 

 taken into consideration. Bolls or portions of bolls that showed 

 themselves to be unfit for picking because of conditions other than 

 the pink bollworm, such as those attacked by the common bollworm, 

 0. obsoleta, or injured by water, heat, and dryness, were counted as 

 sound bolls (Table XVI). 



Table XVI. — Loss to crop in nonpickable cotton caused by the pink bollworm. 



Place. 



Total 

 plants. 



Totalbolls. 



Totalbolls 

 lost. 



Percent 

 damaged 



HnrmipiiPirn. 



248 

 453 

 503 

 454 

 450 

 450 

 300 



6,737 



14,977 

 15,117 

 20,112 

 10, 428 

 9,282 

 6,297 



1,066 

 2,618 

 2,942 

 3,768 

 2,544 

 2,318 

 1,325 



15.82 





17.48 





19.46 





18.73 





24.39 





24.97 



Barcelona 



21.04 







Total 



2,858 



82,950 



16,581 



141. 89 



Average 



19.98 













Table XVI shows that of 82,950 bolls produced by 2,858 plants 

 16,581 were lost, making a total of 19.98 per cent damage in the non- 

 pickable cotton due directly to the attack of the pink bollworm. 

 The plantations on which these figures are based represent a true 

 average of the entire Laguna. In addition to these plantations, a 

 number of other places were visited in different parts of the Laguna 

 and the amount of damage found ranged from 15 to 25 per cent, with 

 an average of approximately 20 per cent loss due to the pink bollworm, 

 which substantiates the accuracy of the foregoing estimates. 



