The influence of acid scarification on the responsiveness of curly dock (Rumex crispus L. ♯ RUMCR) seeds to physical and chemical factors was studied. Scarification made the seeds responsive to GA4+7 (a mixture of gibberellin A4 + A7) and markedly improved the responsiveness to light, moist-chilling, and a 1-h 40-C temperature shift. Scarification reduced the mechanical restraint of the seedcoat by 0.4 to 0.8 MPa. Removal of the entire pericarp induced 69% germination in the dark. Moist-chilling treatment of seeds reduced the soaking period needed for maximum response to the high-temperature shift from 24 to 6 h. The embryo growth potential generated by moist-chilling was less in magnitude than that by the reduction in seed coat restraint by scarification. Induction of secondary dormancy was prevented to a marked degree in scarified (chilled or unchilled) seeds during polyethylene glycol-6000 (PEG) treatment in light or in the presence of GA4+7 while intact seeds rapidly became secondarily dormant in light. The ability of scarified seeds to remain germinable or nondormant for a longer period than the intact seed in low water potential imbibing medium may be due to a net reduction (by 0.4 to 0.8 MPa) in the impact on the embryo of germination-preventing forces (low water potential plus mechanical restraint of the seed coat).

Seed of three weed species collected from the grain bins of combines while standing hard red winter wheat was harvested germinated better than hand-harvested seed. Combine-harvested curly dock seed germinated from 4 to 24% more than hand-harvested seed. Curly dock seed harvested with a commercial-type combine germinated better than those harvested with a small-plot combine. Harvesting slimleaf lambsquarters and Venice mallow seed with a commercial-type combine also enhanced germination compared to hand-harvested seed.

A seed remover using a modified water-spray system was constructed to separate weed seeds rapidly and effectively from a silt loam soil A 1-kg soil sample can be washed through the seed remover in 6 min. Using a 500-μ mesh sieve, only 70% of small shepherdspurse seeds were recovered, while 100% of larger seeds of henbit, curly dock, wild oats, and downy brome were recovered. The modified seed remover system reduced the required man-hours by more than 50% compared to previous systems.

Chemicals that stimulate germination of curly dock seed (Rumex crispus L. # RUMCR) and urediniospores of curly dock rust [Uromyces rumicis Schum. (Wint.)], an obligate parasite of this weed, were studied and compared. Methyl salicylate, benzyl cyanide, and benzonitrile were the best stimulators of germination of curly dock seed. The compounds tested were most effective at concentrations ranging from 250 to 1000 μl/L. A 500 μl/L concentration of methyl salicylate caused 99% of the curly dock seed to germinate. Exposure to volatiles from 10 μl methyl salicylate or octyl cyanide for 16 to 24 h was required for maximum stimulation of curly dock seed germination in 10 days. Benzonitrile, methyl-2,4-dihydroxybenzoate, 3-cyanophenol, 2-heptanone, and benzaldehyde were the most effective of 45 compounds tested on urediniospores of curly dock rust. Benzonitrile was most active of 19 compounds tested on both seed and spores. Benzyl cyanide, 4-methoxybenzonitrile, benzaldehyde, and methyl 2,4-dihydroxybenzoate also were active on both propagules.

Seed dormancy does not play a role in the germination ecology of curly dock (Rumex crispus L. ♯ RUMCR). This study confirms reports that freshly matured seeds are nondormant, and it shows that buried seeds exposed to natural seasonal temperature changes remain nondormant. From October 1981 through June 1983, seeds exhumed at monthly intervals germinated 80 to 100% at all thermo-periods. These results do not support suggestions that seeds of curly dock buried in soil enter dormancy. However, the results do explain why seeds of this species in the Beal and Duvel buried-seed experiments germinated when exhumed at various times during the growing season.

Field experiments were conducted to evaluate postemergence (POST)-applied tank mixtures of 560, 1,120, and 1,680 g ai/ha glyphosate with or without 1,120 g ai/ha SAN 582 (proposed name, dimethenamid) as burndown treatments or POST in glyphosate-tolerant soybean. SAN 582 was not antagonistic with glyphosate at the glyphosate rates evaluated. In the burndown study, glyphosate controlled horseweed 98% or more and curly dock 82% or more with or without SAN 582. However, broadleaf signalgrass emerged after the burndown treatments were applied. All tank mixtures that included SAN 582 controlled broadleaf signalgrass 84 to 96%, 6 wk after treatment. In the glyphosate-tolerant soybean study, glyphosate controlled barnyardgrass and johnsongrass present at the time of application 89% or more, regardless of rate. Tank mixtures of SAN 582 with glyphosate controlled late-season flushes of barnyardgrass through residual activity of the SAN 582. Applying SAN 582 with glyphosate improved soybean yield 500 kg/ha over glyphosate applied alone.