Weed Problems

Pigweed species was the worst weed problem in KS, but foxtail was the worst weed problem in MN, ND and SD. Other common weed problems included Russian thistle in KS, Canada thistle in MN and ND, and wild mustard in MN and ND (Table 28).

Pigweed species was the worst weed problem on 26% of KS respondents' acres, followed by Russian thistle on 24% and kochia on 18%. Kochia was one of the three worst weeds by 64% of KS respondents' acres, followed by pigweed species on 47%, Russian thistle on 38% and foxtail on 35% (Table 28).

Foxtail was the worst weed problem on 35% of MN respondents' acres, followed by Canada thistle on 19% and wild mustard on 18%. Foxtail was one of the three worst weeds on 59% of MN respondents' acres, followed by wild mustard on 51%, Canada thistle on 39%, quackgrass on 29% and wild oat on 27% (Table 28).

Foxtail was the worst weed problem on 29% of ND respondents' acres, followed by wild mustard and Canada thistle, each on 19%. Foxtail was one of the three worst weeds on 58% of ND respondents' acres, followed by wild mustard on 51%, Canada thistle on 50% and kochia on 28% (Table 28).

Foxtail was the worst weed problem on 58% of SD respondents' acres. It was one of the three worst weeds on 69% of SD respondents' acres, followed by Canada thistle on 47%, kochia on 45% and pigweed species on 23% (Table 28).

Herbicide Use and Other Weed Management Practices

Weed control practices included use of herbicides, cultivation and use of rotary hoe. KS respondents used spring-applied Prowl on 45% of their acres, followed by spring-applied trifluralin on 14% of their acres (Table 29). These use figures are similar to 1994 (4).

MN respondents used Assert on 28% of their acres, followed by spring-applied Prowl on 24%, spring-applied Sonalan on 22%, Poast on 20% and spring-applied trifluralin on 15% (Table 29). These data represent a shift to considerably less use of trifluralin than in 1994 and to a slight increase in Prowl use (4).

ND respondents used spring-applied Sonalan on 43% of their acres and spring-applied trifluralin on 31% (Table 29). These data are similar to those for 1994 (4).

SD respondents used spring-applied trifluralin on 31% of their acres, followed by spring-applied Sonalan on 29%, Poast on 14% and spring-applied Prowl on 13% (Table 29). These data represent a shift since 1994 with less use of trifluralin and greater use of other dinitroanaline herbicides and a slight increase in the use of Poast (4).

Desiccant use was minimal in all four states (Table 30). KS and MN respondents used desiccant on 2% of their acres. ND and SD respondents used desiccant on less than 1% of their acres.

Most respondents used a single herbicide application. Only a few respondents in ND and SD used two applications (Table 31). Over 90% of respondents in all four states reported that herbicide application was by ground (Table 32).

Grass weeds were the targeted weeds by 34% of KS, 50% of MN, 56% of ND and 62% of SD respondents. Broadleaf weeds were the targeted weeds by 19% of KS, 27% of MN, 12% of ND and 3% of SD respondents. Grass and broadleaf weeds were the targeted weeds by 47% of KS, 23% of MN, 30% of ND and 32% of SD respondents (Table 33).

Assert was used for wild mustard control by 88% of MN and 89% of ND respondents, followed by wild oat and wild mustard control by 8% of MN and and 6% of ND respondents, respectively (Table 34). Assert was applied by ground by 86% of MN and 85 % of ND respondents (Table 35).

Assert was used at less than 0.1 lb ai/A by 15% of MN and 4% of ND respondents, and from 0.1 to 0.18 lb ai/A by 20% of MN and 34% of ND respondents. Since the label rate for Assert is 0.19-0.25 lb ai/A, below-label rates were used by 35% of MN and 38% of ND respondents. Assert was used at the label rate of 0.19-0.25 lb ai/A by 40% of MN and 46% of ND respondents, and was used at above-label rates of 0.26-0.70 lb ai/A by 25% of MN and 15% of ND respondents (Table 36). Assert was reported to give excellent weed control by 36% of MN and 51% of ND respondents, and to give good control by 52% of MN and 36% of ND respondents (Table 37).

Grass weeds were the targeted weeds for Poast use by 100% of MN, 100% of ND and 92% of SD respondents (Table 38). Poast was applied by ground by 85% of MN, 96% of ND and 92% of SD respondents (Table 39).

Poast was used at rates of 0.10 to 0.19 lb ai/A by 50% of MN and 67% of ND respondents, and at 0.2-0.30 lb ai/A by 25% of MN and 28% of ND respondents (Table 40). Since 0.1 to 0.3 lb ai/A is the label rate, 75% of MN and 95% of ND respondents used Poast at the label rate. Poast was used at above-label rates of 0.3-0.39 lb ai/A by 25% of MN and 6% of ND respondents.

Poast was reported to give excellent control by 18% of MN, 37% of ND and 56% of SD respondents. It was reported to give good control by 55% of MN, 56% of ND and 41% of SD respondents (Table 37).

Grass weeds were the targeted weeds for spring-applied Prowl use by 32% of KS and 50% of SD respondents (Table 41). Grass weeds and broadleaf weeds were the targeted weeds for spring-applied Prowl use by 54% of KS and 42% of SD respondents. Broadleaf weeds were the targeted weeds by 14% of KS and 8% of SD respondents. Spring-applied Prowl was ground applied by 97% of KS, 92% of MN and 88% of ND respondents (Table 42).

Spring-applied Prowl was used at below-label rates of 0.4 to 0.99 lb ai/A by 22% of KS, 27% of MN and 38% of SD respondents (Table 43). It was used at label rates of 1.0-1.5 lb ai/A by 69% of KS, 73% of MN and 54% of SD respondents. It was used at above label rates by only 9% of KS and 8% of SD respondents. Spring-applied Prowl was reported to provide excellent weed control by 14% of KS, 25% of MN and 19% of SD respondents, and to provide good weed control by 39% of KS, 58% of MN and 50% of SD respondents (Table 37).

Grass weeds were the targeted weeds for pre-plant Roundup use by 41% of ND and 10% of SD respondents. Perennial weeds were targeted for pre-plant Roundup use by 35% of ND and 15% of SD respondents. Grass weeds and broadleaf weeds were targeted for pre-plant Roundup use by 24% of ND and 75% of SD respondents (Table 44). Pre-plant Roundup was ground-applied by 100% of KS, 79% of ND and 92% of SD respondents (Table 45).

Pre-plant Roundup was used at 0.19-0.29 lb ai/A by 6% of ND and 20% of SD respondents, at 0.30-0.39 lb ai/A by 25% of ND and 30% of SD respondents, at 0.40-0.59 lb ai/A by 13% of ND and 10% of SD respondents and at 0.75 lb ai/A by 56% of ND and 30% of SD respondents (Table 46). Since the label rate is 0.19-0.75 lb ai/A, all ND and 90% of SD respondents used the label rate. Only 10% of SD respondents used above-label rates of 1.00-1.15 lb ai/A.

Pre-plant Roundup was reported to give excellent weed control by 36% of KS, 48% of ND and 40% of SD respondents. It was reported to give good weed control by 55% of KS, 38% of MN and 36% of SD respondents (Table 37).

Grass weeds were the targeted weeds for spring-applied Sonalan use by 42% of KS, 45% of ND and 74% of SD respondents. Broadleaf weeds were the targeted weeds for spring-applied Sonalan use by 16% of MN, 2% of ND and 3% of SD respondents. Grass and broadleaf weeds were the targeted weeds by 42% of MN, 53% of ND and 23% of SD respondents (Table 47). Spring-applied Sonalan was ground applied by 96% of MN, 100% of ND and 97% of SD respondents (Table 48).

Spring-applied Sonalan was applied at below label rates of 0.19-0.54 lb ai/A by 5% of MN, 1% of ND and 4% of SD respondents. It was applied at label rates of 0.55-0.99 lb ai/A by 53% of MN, 40% of ND and 58% of SD respondents and at 1.00-1.25 lb ai/A by 37% of MN, 55% of ND and 33% of SD respondents (Table 49). Thus, label rates were used by 90% of MN, 95% of ND and 91% of SD respondents. Only 5% of MN, 4% of ND and 4% of SD respondents used above-label rates.

Spring-applied Sonalan was reported to give excellent weed control by 29% of MN, 26% of ND and 34% of SD respondents. It was reported to give good weed control by 48% of MN, 50% of ND and 32% of SD respondents (Table 37).

Grass weeds were the targeted weeds for fall-applied trifluralin use by 82% of ND respondents and grass and broadleaf weeds by 18% (Table 50). Fall-applied trifluralin was ground-applied by 100% of ND respondents (Table 51).

Fall-applied trifluralin was used at 0.5 lb ai/A by 20% of ND respondents, at 0.75 lb ai/A by 7% of ND respondents and at 0.9-1.0 lb ai/A by 53% of ND respondents (Table 52). Since these are all label rates, 80% of ND respondents used fall-applied trifluralin at label rates. The remaining 20% used fall-applied trifluralin at above label rates of 1.1-2.5 lb ai/A. Fall-applied trifluralin was reported to give excellent weed control by 33% of ND respondents and good weed control by another 33% of ND respondents (Table 37).

Grass weeds were the targeted weeds for spring-applied trifluralin use by 16% of KS, 64% of MN, 83% of ND and 68% of SD respondents. Broadleaf weeds were targeted for spring-applied trifluralin use by 26% of KS, 1% of ND and 2% of SD respondents. Grass and broadleaf weeds were targeted for spring-applied trifluralin use by 58% of KS, 36% of MN, 16% of ND and 30% of SD respondents (Table 53). Spring-applied trifluralin was ground applied by 90% of KS, 100% of MN, 100% of ND and 98% of SD respondents (Table 54).

Spring-applied trifluralin was used at 0.50-0.80 lb ai/A by 53% of KS, 37% of MN, 29% of ND and 9% of SD respondents. It was applied at 0.81-1.00 lb ai/A by 47% of KS, 63% of MN, 61% of ND and 83% of SD respondents (Table 55). Since both rates are label rates, 100% of KS, 100% of MN, 90% of ND and 92% of SD respondents used label rates. Above label rates of 1.01-16.00 lb ai/A were used by 9% of ND and 7% of SD respondents. The reported rate of 16 lb ai/A may represent an entry error by the respondent.

Spring-applied trifluralin was reported to give excellent weed control by 24% of KS, 19% of MN, 17% of ND and 25% of SD respondents. It was reported to give good weed control by 52% of KS, 44% of MN, 40% of ND and 34% of SD respondents (Table 37). Spring-applied trifluralin provided only fair weed control for 38% of MN, 30% of ND and 28% of SD respondents.

Row-crop cultivation was used on 41% of KS, 78% of MN, 64% of ND and 48% of SD respondents' acres. Rotary hoe was used on 2% of KS, 4% of MN, 3% of ND and 3% of SD respondents's acres (Table 56). Most respondents used a single cultivation: 93% of KS, 55% of MN, 85% of ND and 77% of SD respondents; two row-crop cultivations were used by 7% of KS, 39% of MN, 13% of ND and 22% of SD respondents (Table 57). Rotary hoe was used in a single cultivation by 100% of KS, MN and ND respondents, and by 86% of SD respondents who answered the question.