CONTROL OF ARGENTINE ANT IN ORANGE GROVES. 11 



Most of the present plantings are budded trees set out since the 

 great freeze of 1899, which killed to the ground every orange tree in 

 the State. These trees are much more susceptible to injury from in- 

 sects and other natural influences encountered in Louisiana than are 

 the seedling trees. The nursery stock was largely of inferior quality, 

 and the trees usually were planted too close together in shallow, wet 

 soil, which encourages the roots to cover a great area close to the 

 surface. The insect pests were allowed to flourish unchecked, all cul- 

 tural care was neglected, and many of the trees were damaged fur- 

 ther by floods, storms, and freezing. As a result a large proportion 

 of them have remained undersized and in poor health. The amount 

 of production has never reached that of normal healthy trees, and at 

 from 7 to 10 years of age both trees and crop began to fail. The 

 maximum production of Louisiana orange trees was but slightly more 

 than three- fourths .of a box per bearing tree, and the present produc- 

 tion is only about one-half of a box per tree. 



The success of certain well-tended orange groves in Louisiana 

 demonstrates that oranges can be grown with profit in the State. 

 The only commercially successful and profitable groves, however, have 

 been those which receive an amount of care and attention much above 

 the average for the State. The Argentine ant now occurs in slightly 

 more than one-fourth of the Louisiana orange groves. 



Comparison of the condition of the trees and the amount of the 

 crop in ant-invaded groves with those in groves in which there are no 

 ants shows that only about one-sixth more of the trees of the former 

 are in poor condition than of the latter, while the average reduction 

 in crop is only about one-fifth greater per tree in ant-invaded groves. 

 This difference probably is due largely to the greater neglect of ant- 

 infested trees because of discouragement at the invasion of the ant. 



There are, of course, a number of groves in Louisiana that con- 

 sist of trees of such poor quality and in such a run-down condition 

 that they will never repay the cost of reclamation. There are others, 

 however, that can be so improved by spraying, cultivation, and 

 pruning that the production will be more than doubled in a single 

 season and still further increased by continued treatment. 



In Louisiana, therefore, the improvement of cultural conditions 

 and the control of the armored scales, white fly, and rust mite, the 

 principal injurious pests, are absolutely imperative if orange grow- 

 ing is to be made successful, even where the Argentine ant is not pres- 

 ent. These insects can be controlled, even with the ant present, by 

 following a properly arranged program of spraying, 1 and they can not 



1 For effective insecticides and directions for spraying, see Farmers' Bulletin 933, 

 " Spraying for the Control of Insects and Mites Attacking Citrus Trees in Florida," 

 which may be obtained free from the Division of Publications, United States Department 

 of Agriculture. 



