were made at 7 to l8-day intervals, there was little effect on the rapidly 

 developing boll weevil populations. 



No attempt has been made to compare the effectiveness of the insecti- 

 cides used because of the wide variation in application methods and equip- 

 ment. 



Data on oviposition and feeding damage (table 1) show that complete 

 kill of overwintered weevils entering the fields was not obtained. How- 

 ever, infestations were greatly reduced in all fields receiving Ij. or 5 

 applications of Guthion, or Guthion plus DDT. At the end of the emergence 

 period the infestation was less than 0.8 percent punctured squares in 

 all such fields except in field 9 in which it was 1.2lj. percent, indicating 

 that adult populations were reduced to low levels during the treatment 

 period. 



Complete kill was not obtained, at least in part, because of exces- 

 sive rainfall throughout the treatment period, which made it impossible • 

 for growers to maintain the 5-day-interval application schedule. The 

 intervals ranged from 2 to 11 days. In many instances, substantial amounts 

 of rain fell shortly after the insecticides were applied, which materially 

 decreased their effectiveness. 



In fields that received early-season treatment, maximum oviposition 

 occurred on August 21 or 22, with the exception of fields 9 and 10, where 

 it occurred on August l5 or l6. In the three fields that did not receive 

 early-season treatment, maximum oviposition occurred on or before July 

 31, approximately 3 weeks earlier than in the treated fields. Higher 

 weevil infestations developed sooner in fields 9 and 10 than in the other 

 early-treated fields This was due in part to an 11-day interval between 

 early-season applications 3 and h in field 9 and the delay in beginning 

 the late-season treatments until August l6 in field 10. 



Field 13 consistently had a higher weevil infestation, which neces- 

 sitated continued treatment. In spite of this, the infestation reached 

 the 10-percent punctured square level before August 2. The 10-percent 

 infestation level occurred in control fields l5 and l6 before July 31, 

 and in field lU before July 10 . The infestation in all other fields except 

 1, 9, 10, and 12 reached this level on August l5 or l6. The infestation 

 did not reach the 10-percent level in field 1 until August 21; in fields 9 

 and 12, on July 31; and in field 10, on August 7. 



In fields receiving the most effective schedule of applications 

 (tables i; to 6), the number of weevils present, based on the numbers of 

 egg and feeding punctures, and percent of infestation, remained at low 

 levels during the periods of the overwintered and Fq_ generations . How- 

 ever, the numbers increased rapidly during the peak emergence and ovi- 

 position of the F2 generation during the third week of August. Egg punc- 

 tures increased from 100 or less per acre at the end of June to 10,000 

 or more per acre during the third week of August (tables I4. to 7). In 

 field 13, where the infestation was consistently higher, egg punctures 

 increased from 399 per acre at the end of June to 38^990 during the third 

 week of August (table 6). In field 1$ , which received only one insecti- 

 cide application on July 26, peak oviposition occurred on or before the 

 end of July (table 7). 



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