Acid-scarified hogpotato (Hoffmanseggia densiflora Benth. ex. Gray # HOFDE) seed incubated in distilled water germinated at least 94% when incubated at constant 15, 20, 30 C, and at alternate 20/30 C (20 C for 16 h and 30 C for 8 h) temperatures. Highest germination in buffered solutions occurred at pH 5.0 and 6.0 with reduced germination at lower and higher pH levels. Sodium chloride concentrations of 50 mM and greater reduced the germination rate. Percent germination after 9 days was reduced at NaCl concentrations of 100 mM and greater. Radicle lengths measured after 3 days were significantly reduced with increasing NaCl concentration. Twenty-day-old hogpotato seedlings having three true leaves were able to resprout after topgrowth removal. Regrowth occurred on 15% of the seedlings approximately 15 days after top removal.

Three field experiments were conducted in 1987 through 1989 to evaluate hogpotato control and rotational crop response resulting from applications of five herbicides. At the end of the first year, triclopyr and imazapyr controlled hogpotato late-season as high as 87 and 94%, respectively. Following a sequential application in 1988, triclopyr and imazapyr controlled 94 and 100% of hogpotato, respectively, during the 1989 growing season. Hogpotato biomass, collected at the termination of the experiments, was reduced by all treatments at all locations except at Altus where dicamba was applied in 1987 followed by a spot application of glyphosate in 1988. Soils from these experiments were bioassayed for residual herbicide activity using three potential rotational crop species. Tebuthiuron and imazapyr caused the greatest biomass reductions with cotton and wheat being the most sensitive species to these herbicides.

The effects of hogpotato interference on cotton and of the crop on the weed were measured under field conditions in four environments. Full-season interference from 105 ± 21 hogpotato plants/m2 reduced cotton plant height by 14 to 44%. Conversely, weed dry weight was reduced 54% through full-season interference from cotton. Lint yield reductions in cotton ranged from 31 to 98% following full-season weed interference. Interference during the first 7 weeks of crop growth reduced lint yield by approximately 40%; however, interference after 7 weeks of weed-free maintenance did not affect lint yield. Interference reduced boll size in 3 of 4 yr, lint percent in 2 of 4, and boll number in the only year it was measured. Cotton fiber length, uniformity index, and micronaire were reduced by full-season interference in 1 of 2 yr; however, fiber strength was not affected in either year. Significant use of soil water by hogpotato occurred at 120 cm and deeper in the soil while cotton used water primarily in the upper 75 cm.