Broadleaf weed control in sugar beet with soil

Broadleaf Weed Control in Sugar Beet with Soil-Applied and Sequential Postemergence Herbicides
Compared to Micro Herbicide Rates

Don W. Morishita and Michael J. Wille
Twin Falls Research and Extension Center
University of Idaho

Introduction

A study was conducted at the University of Idaho Research and Extension Center near Kimberly, ID to compare the effectiveness of micro herbicide rates of Nortron & desmedipham & phenmedipham (Progress) with other herbicide treatments for weed control in sugar beet.

Materials and Methods

Sugar beet (‘HM PM-21’) was planted April 18, 2000, on 22-inch rows at a seeding rate of 57,024 seed/A and grown under sprinkler irrigation. Soil type was a Portneuf silt loam (26% sand, 64% silt, and 10% clay, pH 8.1, 1.6% organic matter, and CEC of 16 meq/100 g soil). The experiment was designed as a randomized complete block with four replications. Individual plots were 4 rows by 30 ft. All herbicides were applied with a CO₂-pressurized bicycle-wheel sprayer.

Treatments using micro herbicide rates were broadcast-applied at 10 gpa using 11001 flat-fan nozzles spaced 15 inches apart. All other treatments were applied in 10-inch bands at 20 gpa using 8001 even-fan nozzles spaced 22 inches apart. Additional application information and weed species densities are shown in Table 1. Weed control was evaluated visually June 15 and June 27, 8 and 20 days after last applications (DALT). Sugar beet was harvested from the center two rows of each plot with a mechanical harvester on September 21.

Table 1. Application data and weed species densities.


Application date	4/24	5/13	5/22	5/27	6/7
Application timing	PRE	cotyledon	9 d after cotyledon 2-leaf	14 d after cotyledon 5 d after 2-leaf	11d after2-leaf
Air temperature (F)	54	47	80	70	70
Soil temperature (F)	29	50	64	64	64
Relative humidity (%)	48	52	25	25	57
Wind speed (mph)	5	1	8	8	4
Cloud cover (%)	100	10	40	40	0

Weed species/ft²
common lambsquarters	0	0	25	24	25
kochia	0	6	3	2	1
redroot pigweed	0	0		10	16

Results and Discussion

None of the herbicide treatments injured sugar beet (Table 2). Kochia control 8 DAT ranged from 67 to 100%, and 78 to 100% 20 DAT but differences among treatments could not be distinguished. Common lambsquarters control 8 DAT was ³95% for all treatments except those consisting of two applications of Progress + UpBeet at 18 fl oz + 0.5 oz/A with the addition of Outlook at either 14 or 28 fl oz/A in the second application which controlled kochia 87 to 88%. All herbicide treatments controlled common lambsquarters ³93% 20 DAT except two applications of Progress + UpBeet at 18 fl oz +0.5 oz/A plus Outlook at 14 fl oz/A in the second application which controlled common lambsquarters 78%. Redroot pigweed control, which was evaluated on June 26 only, was ³97% for all herbicide treatments and did not differ among treatments. Sugarbeet yield was similar for all herbicide-treated plots, ranging from 17 to 29 tons/A, compared to 6 tons/A for the untreated check.

Table 2. Broadleaf weed control in sugar beets with soil-applied and sequential postemergence herbicides compared to micro herbicide rates.

Weed Control^a

Application

Crop Injury

kochia

colq

rrpw

Treatment^b

Rate

timing

6/15

6/27

6/15

6/27

6/15

6/27

Yield

product/A

-------------------------------%-----------------------------

tons/A

Check

Ro-Neet +

0.5 gal +

100

Touchdown +

1 qt +

NIS

0.25% v/v

Progress +

18 fl oz +

C, D

UpBeet +

0.5 oz +

Stinger

4 fl oz

Nortron +

1.12 qt +

100

Roundup Ultra

1 qt +

Progress +

18 fl oz +

C, D

UpBeet +

0.5 oz +

Stinger

4 fl oz

Progress +

18 fl oz +

UpBeet

0.5 oz

Progress +

18 fl oz +

UpBeet +

0.5 oz +

Outlook

14 fl oz

Progress +

18 fl oz +

UpBeet

0.5 oz

Progress +

18 fl oz +

UpBeet +

0.5 oz +

Outlook

28 fl oz

Betamix +

25 fl oz +