A Biotype of Hare Barley (Hordeum leporinum) Resistant to Paraquat and Diquat

A biotype of the annual grass weed hare barley infesting an alfalfa field with a 24-yr history of the use of the bipyridylium herbicides paraquat and diquat, was investigated for resistance to these herbicides. Rates of up to 800 g ai ha–1of each herbicide caused no mortality in the hare barley plants from this field. The same species, collected from an adjacent pasture field with no history of bipyridylium herbicide application, exhibited LD50'sof 57 and 160 g ai ha–1for paraquat and diquat, respectively. Tiller numbers and dry matter production in the biotype from the alfalfa field were not affected by the normal rate recommended for both herbicides. These results clearly show that hare barley from the alfalfa field is resistant to paraquat and diquat. Both biotypes were equally sensitive to fluazifop, glyphosate, and sethoxydim.

Download Full-text

Field pea cultivar and weed response to crop seed rate in western Canada

Canadian Journal of Plant Science ◽

10.4141/cjps94-074 ◽

1994 ◽

Vol 74 (2) ◽

pp. 387-393 ◽

Cited By ~ 26

Author(s):

L. Townley-Smith ◽

A. T. Wright

Keyword(s):

Dry Matter ◽

Growth Habit ◽

Stand Density ◽

Field Pea ◽

Dry Matter Production ◽

Herbicide Application ◽

Seed Rate ◽

Pisum Sativum L ◽

Matter Production ◽

Long Stem

Weed competition is a serious limitation to field pea (Pisum sativum L.) production. Trials were conducted in northeastern Saskatchewan to determine the effects of field pea growth habit, stand density and herbicide treatments on weed growth and on field pea stand and yield. Century, a long-stem leafy type, Tipu, a long-stem semi-leafless type, and Express, a short-stem leafy type, were seeded at 6, 12, 25, 50 and 100 seeds m−2. Some of each cultivar was unsprayed sprayed with a sethoxydim-metribuzin tank-mix for control of grass and broadleaf weeds. Field pea growth habit (cultivar) did not affect number of weeds, but increasing stand density (seed rate) reduced weed numbers in all 3 yr. Express reduced above-ground dry matter production of broadleaf weeds in 1988 and 1991. Increasing seed rate reduced above-ground dry matter production of weeds in all 3 yr. Field pea yield increased with increasing seed rate to a rate between 50 and 100 seeds m−2. Herbicide application reduced weed dry matter production, with the largest effect at low field pea populations. Despite differences in growth habit, the three cultivars competed similarly with weeds. High populations of field peas competed well with weeds and may not require herbicide application, but if producers retain thin stands, good weed control will be critical to attaining high crop yield. Key words: Field pea, Pisum sativum L., seed rate, weed competition, growth habit

Download Full-text

PASTURE RENOVATION BY OVERDRILLING

Proceedings of the New Zealand Grassland Association ◽

10.33584/jnzg.1986.47.1749 ◽

1986 ◽

pp. 159-163

Author(s):

W.R. Ritchie

Keyword(s):

Dry Matter ◽

Red Clover ◽

Dry Matter Production ◽

Research Centre ◽

No Tillage ◽

Agricultural Machinery ◽

Herbicide Application ◽

Medium Term ◽

Matter Production ◽

Direct Drilling

The Agricultural Machinery Research Centre, Massey University, undertook pasture renovation with a prototype direct drill at several North Island sites. Banded herbicide application was found to provide an effective medium term (two years) means of introducing ryegrass and clover species into browntop dominant pastures being intensively grazed. Specialist pasture species were introduced into Northland dairy pastures by band spraying and direct drilling. Wana cocksfoot and Pawera red clover were slower to establish than Nui and Ellett ryegrass. All species contributed to greater herbage dry matter production of the sward than the control and appeared to be persisting competitively. Keywords: Direct drilling, overdrilling, band spraying, winged opener, inverted T slot, pasture renewal, pasture renovation, prototype direct drill, Northland, Taranaki, Manawatu, no-tillage.

Download Full-text