Micro herbicide rates for broadleaf weed control in sugar beet

Micro herbicide rates for broadleaf weed control in sugar beet

Corey V. Ransom, Don W. Morishita, Michael J. Wille, Joey K. Ishida, and Corey Guza

INTRODUCTION

For the past two years, studies have been conducted at the University of Idaho Research and Extension Center near Kimberly, ID and the Oregon State University Malheur Experiment Station near Ontario, OR to determine the effectiveness of below-label herbicide rates for weed control in sugar beet. Most postemergence herbicides used in sugar beet are applied in 7-inch bands. The basis of the micro-rate concept is to apply the same amount of active ingredient used in a 7-inch band in a broadcast application. The purpose of these experiments was to evaluate micro heribicide rates in Idaho and Oregon as broadcast and band applications to see if they work in our environment.

MATERIALS AND METHODS

Methylated seed oil (MSO) was added to all micro-rate applications at both locations. At Kimberly, micro- rate treatments also were applied with the drift reduction adjuvant PlacementÒ . Sugar beets (‘WS PM9’) were grown under sprinkler irrigation at Kimberly and furrow irrigated at Ontario. The first herbicide applications for all treatments began at the sugar beet cotyledon stage followed by two sequential applications 6 and 15 days later at Kimberly, and three sequential applications at Ontario 7, 16, and 24 days later. A standard herbicide rate was band-applied for comparison to broadcast and band applications of the micro-rates at both locations. Broadcast applications were made with 11001 flat fan nozzles at Kimberly and 8002 nozzles at Ontario. Band applications at both locations were made with 8001 even fan nozzles. All treatments were applied using a CO₂-pressurized bicycle-wheel sprayer at Kimberly and a backpack sprayer at Ontario. Kochia and common lambsquarters were the major weed species present at Kimberly and averaged 40 and 8 plants/ft², respectively. The experimental design at both locations was a randomized complete block with four replications. Individual plots were four rows by 25 or 30 ft. Crop injury and weed control were evaluated June 15 and 24 at Ontario and Kimberly, respectively. On July 1, all plots at Kimberly except the check were handweeded and the times recorded. Sugar beet was harvested from the middle two rows of each plot September 29.

RESULTS AND DISCUSSION

Sugar beet was not seriously injured by any herbicide treatment at either location (Tables 1 and 2). At Kimberly common lambsquarters control ranged from 98 to 100% with all herbicide treatments (Table 1). Kochia control was generally poor with all herbicide treatments except the standard rate of Progress + UpBeet applied twice followed by the same combination plus Stinger at the third application. Band applications of the micro rate controlled common lambsquarters as well as the broadcast applications. Neither broadcast or band micro rate applications satifactorily controlled kochia. Due to poor kochia control, all herbicide treatments were handweeded. However, hoeing time for each treatment was variable and no differences were observed among treatments. All herbicide treatments yielded higher than the untreated check, which yielded only 1 ton/A, but there were no differences among herbicide treatments. Sugar beet yields among herbicide treatments ranged from 10 to 17 ton/A. At Ontario, all broadcast herbicide treatments controlled redroot pigweed, common lambsquarters, hairy nightshade, and annual sowthistle 93% or better (Table 2). Band-applied treatments were generally less effective than broadcast treatments at Ontario because cultivation did not remove weeds surviving at the edge of the herbicide treated band. Using Progress or Betamix in the micro-rate provided similar weed control. Root yields and estimated recoverable sugar were improved by all treatments compared to the check, but were not different among the herbicide treatments. Using the micro-rate program requires more frequent herbicide applications, but allows producers to broadcast apply their herbicides and may reduce the number of cultivations needed during the growing season.

Table 1. Crop injury, weed control, hoeing time, and beet yield with micro herbicide rate applications, University of Idaho Research and Extension Center, Kimberly, ID.

		Application				Weed Control^a
Treatment^b	Rate	type	volume	timing	Crop Injury	colq	koch	Hoeing Time	Yield

	oz/A		gpa		-----------%-----------			hr/A	ton/A

Check					-	-	-		1

Progress+ UpBeet	6+ 1/6	7" band	20	cotyledon,	0	99	78	61	17

Progress+ UpBeet+ Stinger	6+ 1/6+ 1 1/3			6, and 9 days later

Progress+ UpBeet+ MSO	3+ 1/12+ 1.5%v/v	7" band	20	cotyledon,	0	99	50	85	14
Progress+ UpBeet+ Stinger+ MSO	3+ 1/12+ 2/3+ 1.5% v/v			6, and 9 days later

Progress+ UpBeet+ Stinger+ MSO	3+ 1/12+ 2/3+ 1.5% v/v	10" band	20	cotyledon, 6, and 9 days later	0	100	20	131	13

Progress+ UpBeet+ Stinger+ Placement	3+ 1/12+ 2/3+ 6	10" band	20	cotyledon, 6, and 9 days later	0	98	30	91	15

Progress+ UpBeet+ Stinger+ MSO	6+ 1/6+ 1 1/3+ 1.5% v/v	broadcast	10	cotyledon, 6, and 9 days later	0	98	60	53	12

Progress+ UpBeet+ Stinger+ MSO	6+ 1/6+ 1 1/3+ 1.5% v/v	broadcast	20	cotyledon, 6, and 9 days later	0	100	23	121	10

Progress+ UpBeet+ Stinger+ Placement	6+ 1/6+ 1 1/3+ 6	broadcast	10	cotyledon, 6, and 9 days later	0	100	28	91	17

LSD (0.05)					ns	3	24	ns	8

^{aWeed species evaluated were common lambsquarters
(colq) and kochia (koch).

^{bMSO = methylated seed oil, and Placement is a proprietary adjuvant.

Table 2. Crop injury, weed control, and beet yield with micro-rate herbicide
applications, Oregon State University, Malheur Experiment Station, Ontario, OR.

Weed control^b

Treatment^a
Rate
Application type
Crop injury
Rrpw
Colq
Hans
Bygr
Yield

oz/A

-------------------%-------------------
ton/acre

Untreated

0
0
0
0
0
11

Progress+

UpBeet+

Stinger

6+

1/6+

1.33

7" band
5
82
93
70
78
39

Progress+

UpBeet+

Stinger+

MSO

16+

0.5+

2+

1.5%v/v

Broadcast
2
100
100
96
89
42

Progress+

UpBeet+

Stinger+

MSO

6+

1/6+

1.33+

1.5%v/v

Broadcast
2
95
100
94
73
42

Progress+

UpBeet+

Stinger+

MSO

3+

1/12+

2/3+

1.5%v/v

7" band
0
78
95
68
70
39

Progress+

UpBeet+

Stinger+

MSO+ Assure II

6+

1/6+

1.33+

1.5%v/v+

0.44

Broadcast
3
93
100
96
98
41

Progress+

UpBeet+

Stinger+

MSO+ Assure II

3+

1/12+

2/3+

1.5%v/v+

0.44

7" band
0
80
92
67
83
39

Betamix+

UpBeet+

Stinger+

MSO

8+

1/6+

1.33+

1.5%v/v

Broadcast
0
100
100
94
90
40

LSD(0.05)

ns
13
8
15
12
5

^{aTreatments were applied April 24, May 1, May 10,
and May 18.

^{bWeeds evaluated for control were redroot pigweed (Rrpw), common
lambsquarters (Colq), hairy nightshade (Hans), and barnyardgrass (Bygr). Weed
control and sugar beet injury evaluations were taken June 15.

______________________

Presented at the Snake River Sugar Beet Conference on January 13-14, 2000.}}}}

				Weed control^b
Treatment^a	Rate	Application type	Crop injury	Rrpw	Colq	Hans	Bygr	Yield

	oz/A		-------------------%-------------------					ton/acre

Untreated			0	0	0	0	0	11

Progress+ UpBeet+ Stinger	6+ 1/6+ 1.33	7" band	5	82	93	70	78	39

Progress+ UpBeet+ Stinger+ MSO	16+ 0.5+ 2+ 1.5%v/v	Broadcast	2	100	100	96	89	42

Progress+ UpBeet+ Stinger+ MSO	6+ 1/6+ 1.33+ 1.5%v/v	Broadcast	2	95	100	94	73	42

Progress+ UpBeet+ Stinger+ MSO	3+ 1/12+ 2/3+ 1.5%v/v	7" band	0	78	95	68	70	39

Progress+ UpBeet+ Stinger+ MSO+ Assure II	6+ 1/6+ 1.33+ 1.5%v/v+ 0.44	Broadcast	3	93	100	96	98	41

Progress+ UpBeet+ Stinger+ MSO+ Assure II	3+ 1/12+ 2/3+ 1.5%v/v+ 0.44	7" band	0	80	92	67	83	39

Betamix+ UpBeet+ Stinger+ MSO	8+ 1/6+ 1.33+ 1.5%v/v	Broadcast	0	100	100	94	90	40

LSD(0.05)			ns	13	8	15	12	5