A four-year field study on five alternative rice stand establishment techniques was conducted in the Northern Sacramento Valley of California. The following systems have been evaluated since 2004: 1) conventional water-seed rice, 2) conventional drill-seeding, 3) water-seeding after spring tillage and a stale seedbed, 4) water-seeding after a stale seedbed without spring tillage, and 5) drill-seeding after a stale seedbed without spring tillage. These systems have demonstrated their potential for manipulating the kinds of weed species that emerge with rice. There were drastic differences in weed recruitment among systems, thus aquatic sedge and broadleaf weeds dominated the water-seeded systems, while the aerobic seedbeds of the drill-seeded systems favored early watergrass and barnyardgrass (Echinochloa spp.) and sprangletop (Leptochloa fascicularis). The stale seedbed technique (promotion of weed emergence with irrigation flushes, followed by pre-plant burn-down application of glyphosate) was extremely useful in depleting weed populations from the upper soil layer and diminishing weed emergence with the crop. If this technique was followed by no or limited soil disturbance prior to seeding rice, very little weed control was needed thereafter. In 2008, (fifth year), treatments were changed in plots from this experiment. Plots where rice had been conventionally water seeded for four years were heavily infested with aquatic weeds, these almost disappeared when rice was no-till drilled following a stale seedbed in 2008. Plots with heavy barnyardgrass and sprangletop infestations after 4 years of drill seeding rice were switched in 2008 to water seeding after a stale seedbed without any spring tillage; weeds were almost eliminated from these plots. All this was achieved only using glyphosate ( stale-seedbed treatment), other herbicides could still be applied for 100% weed control and to prevent seed set by late emerging weeds. Alternating rice establishment systems from aerobic (dry seeding) to anaerobic (water seeding) regimes (and vice versa), combined with the pre-plant use of a total non-selective herbicide for which resistance does not yet exist in weeds of rice allowed for a major reduction of herbicide resistant weed infestations and to lower herbicide use. Yields were never different across treatments.
Alternative Rice Stand Establishment Systems to Manage Herbicide Resistant Weeds
M. Milan;
2009-01-01
Abstract
A four-year field study on five alternative rice stand establishment techniques was conducted in the Northern Sacramento Valley of California. The following systems have been evaluated since 2004: 1) conventional water-seed rice, 2) conventional drill-seeding, 3) water-seeding after spring tillage and a stale seedbed, 4) water-seeding after a stale seedbed without spring tillage, and 5) drill-seeding after a stale seedbed without spring tillage. These systems have demonstrated their potential for manipulating the kinds of weed species that emerge with rice. There were drastic differences in weed recruitment among systems, thus aquatic sedge and broadleaf weeds dominated the water-seeded systems, while the aerobic seedbeds of the drill-seeded systems favored early watergrass and barnyardgrass (Echinochloa spp.) and sprangletop (Leptochloa fascicularis). The stale seedbed technique (promotion of weed emergence with irrigation flushes, followed by pre-plant burn-down application of glyphosate) was extremely useful in depleting weed populations from the upper soil layer and diminishing weed emergence with the crop. If this technique was followed by no or limited soil disturbance prior to seeding rice, very little weed control was needed thereafter. In 2008, (fifth year), treatments were changed in plots from this experiment. Plots where rice had been conventionally water seeded for four years were heavily infested with aquatic weeds, these almost disappeared when rice was no-till drilled following a stale seedbed in 2008. Plots with heavy barnyardgrass and sprangletop infestations after 4 years of drill seeding rice were switched in 2008 to water seeding after a stale seedbed without any spring tillage; weeds were almost eliminated from these plots. All this was achieved only using glyphosate ( stale-seedbed treatment), other herbicides could still be applied for 100% weed control and to prevent seed set by late emerging weeds. Alternating rice establishment systems from aerobic (dry seeding) to anaerobic (water seeding) regimes (and vice versa), combined with the pre-plant use of a total non-selective herbicide for which resistance does not yet exist in weeds of rice allowed for a major reduction of herbicide resistant weed infestations and to lower herbicide use. Yields were never different across treatments.
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