Insecticide Use and Other Insect Management Practices. KS respondents treated 52% of their acres with an insecticide; MN respondents treated 30% of their acres with an insecticide; ND respondents treated 62% of their acres with an insecticide; SD respondents treated 58% of their acres with an insecticide. (Table 11). Aerial spraying was the most common method of insecticide application in KS. Aerial and ground spraying were about equally common in MN, and aerial application was more common in ND and SD (Table 12). Most respondents used only one application of insecticide; 89% of KS, 93% of MN, 92% of ND and 97% of SD respondents used a single application (Table 13).

Methyl parathion was the most commonly used insecticide in KS, where it was used on 12% of respondents' acres, followed by Furadan on 9%, Lorsban on 7% and ethyl parathion on 6% (Table 14). Total parathion use (methyl, ethyl and 6-3 ethyl methyl parathion) was on 18% of KS, 2% of MN, 1% of ND and 6% of SD respondents' acres (Table 15). The pyrethroid Asana XL (esfenvalerate) was the most commonly used insecticide in MN, ND and SD, where it was used on 27%, 41% and 31% of respondents' acres, respectively. Another pyrethroid, Warrior, was used on 12% of KS and 15% of ND respondents' acres. Lindane/maneb seed treatment was used on 11% of SD respondents' acres (Table 14).

The sunflower head moth was the insect species most frequently targeted for insecticide control by 69% of KS respondents who answered the question. The stem weevil was second, cited by 12%. The sunflower beetle was the insect species most frequently targeted for insecticide control in MN, ND and SD, cited by 89%, 68% and 43% of respondents in those respective states. The seed weevil was cited by 12% of MN and 25% of SD respondents. Grasshoppers were cited by 16% of SD respondents and the stem weevil by 9% of ND respondents. These data represent the combined use patterns by respondents for all insecticides in the respective states (Table 16).

Asana XL was the insecticide used to control sunflower beetle by 100% of MN, 76% of ND and 56% of SD respondents who used it. It also was used against grasshoppers and seed weevil, as reported by 18% of SD respondents (Table 17).

Asana XL was aerially applied by 46% of MN, 69% of ND and 68% of SD respondents, respectively (Table 18). The Section 3 Asana XL label is for use at 2.9-5.8 fl oz/A for control of sunflower beetles, and at 5.8-9.6 fl oz/A for grasshoppers and seed weevils. In 1997, a Section 2(ee) label was issued for ND, SD, MN and MT for control of sunflower beetles with a low use rate of 1.45 fl oz/A. Asana XL was applied at rates below 1 fl oz/A by 48% of MN and 8% of ND respondents. Rates between 1.0 and 1.45 fl oz/A were used by 14% of MN, 24% of ND and 7% of SD respondents. It was used at the Section 2(ee) label rate of 1.45-2.8 fl oz/A by 29% of MN, 34% of ND and 27% of SD respondents. It was used at Section 3 label rates of 2.9-5.8 fl oz/A by 10% of MN, 28% of ND and 45% of SD respondents. It was used at Section 3 label rates of 5.9-9.6 fl oz/A (rate for insects other than the sunflower beetle) by 4% of ND and 18% of SD respondents (Table 19).

In spite of frequent low use rates, including below-label rates, for Asana XL in MN and ND, 66% of MN, 63% of ND and 42% of SD respondents reported excellent insect control; another 29% of MN, 35% of ND and 52% of SD respondents reported good insect control (Table 20). The greatest use of low rates was in MN, where 100% of respondents used Asana XL for sunflower beetle control; the least use of low rates was in SD, where only 56% of respondents used Asana XL for sunflower beetle control: the data for ND were intermediate to the other two states.