Insect Problems

The stem weevil was rated the worst insect problem on 36% of KS respondents' acres, followed by sunflower head moth on 33%. The sunflower head moth was rated one of the three worst insect problems on 76% of KS respondents' acres, followed by the stem weevil on 56% and grasshoppers on 42% (Table 10).

The sunflower midge was rated the worst insect problem on 52% of MN respondents' acres followed by the sunflower beetle on 24%. The sunflower midge was rated one of the three worst insect problems on 74% of MN respondents' acres, followed by the sunflower beetle on 64% and the seed weevil on 37%.

The sunflower beetle was ranked the worst insect problem on 58% of ND respondents' acres, followed by the sunflower midge on 13%. The sunflower beetle was ranked one of the three worst insect problems on 78% of ND respondents' acres, followed by the seed weevil on 41% and the sunflower midge on 31%.

The stem weevil and the sunflower beetle were each ranked the worst insect problem on 26% of SD respondents' acres, followed by the seed weevil on 20%. The seed weevil was ranked one of the three worst insect problems on 73% of SD respondents' acres, followed by the stem weevil on 45%, the sunflower beetle on 44%, the sunflower head moth on 32% and grasshoppers on 29% (Table 10).

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.

The sunflower head moth was the targeted insect for methyl parathion use by 73% of KS respondents who used it, followed by the banded sunflower moth by 18% and the seed weevil by 9%. The sunflower head moth was the targeted insect for all parathion use by 81% of KS, respondents, followed by the banded sunflower moth by 14% and the seed weevil by 5% (Table 21). Parathion was applied by air by all reporting respondents in KS and SD (Table 22).

Methyl parathion was used at 1-4 fl oz/A by 39% of KS respondents, at 8 fl oz by 23%, at 16 fl oz by 15% and above 16 fl oz by 23% (Table 23). Eight percent of respondents reported using methyl parathion at a rate of 32 fl oz/A. Parathion efficacy was reported to be excellent by 18%, good by 36%, fair by 36% and poor by 9% of KS reporting respondents (Table 20). Labeled rates for methyl parathion 8EC were 8 to 16 fl oz/A, and for methyl parathion 4EC was 32 fl oz/A. Only the 8 pound formulation is now available.

The sunflower head moth was the targeted insect for Warrior use by 69% of KS respondents who used it, followed by the stem weevil by 13%. The sunflower beetle was the targeted insect for Warrior use by 67% of ND respondents who used it, followed by the stem weevil for 19% and the seed weevil by 8% (Table 24). Warrior was applied by air by 90% of KS, 71% of ND and 71% of SD respondents (Table 25).

Warrior is labeled for use at 1.28-2.56 fl oz/A for control of sunflower beetle and at 2.56-3.84 fl oz/A for control of stem weevil and head moth. It was used at less than 1 fl oz/A by 27% of ND respondents and at 1.0-1.27 fl oz by 23% of ND respondents (Table 26). Thus, 50% of ND respondents used Warrior at below-label rates. Warrior was used at the label rates for sunflower beetle of 1.28-2.56 fl oz/A by 23% of KS and 41% of ND respondents; it was used at the 2.57-3.84 rate for other sunflower insects by 62% of KS and 5% of ND respondents. These differences in use patterns between KS and ND reflect the differences in pest problems, with 67% of ND respondents using Warrior for the sunflower beetle. In spite of low use rates, Warrior efficacy was rated excellent by 42% of KS and 63% of ND respondents and good by 58% of KS and 29% of ND respondents. It was rated as fair by only 7% of ND respondents (Table 20).

Respondents in all four states reported using crop rotation as a means of non-chemical insect management. This practice was reportedly used on 41% of KS, 74% of MN, 59% of ND and 75% of SD respondents' acres. Tillage was reported as a means of non-chemical insect management on 14% of KS, 22% of MN, 30% of ND and 41% of SD respondents' acres. Hybrid selection was reported as a means of non-chemical insect management on 3% of KS, 23% of MN, 10% of ND and 26% of SD respondents' acres (Table 27). The use of crop rotation is similar to use patterns in 1994, but the use of tillage was higher in 1997 than in 1994 in MN and SD (4).