Field experiments were conducted in 1986 to 1990 to determine the effect of different rates and application times of BAS 514 and dithiopyr alone and in combination on control of large crabgrass and dandelion in Kentucky bluegrass, tall fescue, and perennial ryegrass. Herbicides evaluated were applied PRE, early POST, and late POST. Results indicated that both herbicides provided excellent PRE control in all years. BAS 514 rates ranged from 0.84 to 0.56 kg ai ha-1. Rates of dithiopyr ranged from 0.43 to 0.56 kg ai ha-1. In addition to crabgrass control, both herbicides controlled dandelion, BAS 514 exhibiting slightly better activity than dithiopyr. BAS 514 at 0.84 to 1.12 kg ai ha-1 and dithiopyr at 0.26 to 0.56 kg ai ha-1 resulted in excellent early POST crabgrass control when applied at the one- to three-leaf stage of crabgrass. BAS 514 and dithiopyr applied late POST (2 to 3 tillers of crabgrass) resulted in 63 to 85% control of crabgrass and 29 to 85% control of dandelion at 10 wk after application. No weed control enhancement was evident from tank mixing the two herbicides. Excellent turf safety was demonstrated by both herbicides on all three turf species.

Sweet corn was grown with a living mulch of white clover, a dead mulch of rye, and without mulch, in both till and no-till conditions. Unplanted controls were also included in the experimental design. Corn yields were highest in clover treatments early in the experiment but lowest in later years. The declining yields in the clover living mulch were related to the strip application of glyphosate which allowed establishment of perennial and biennial weeds, notably dandelion and horseweed. These overwintering weeds apparently prevented effective control of summer annuals, especially redroot pigweed, common lambsquarters and large crabgrass, by atrazine and metolachlor. Presence of a rye mulch decreased weed biomass and had no detrimental effect on corn yield. In general, corn yield was not affected by tillage, although the number of marketable ears was reduced in the no-till treatments during the drought year of 1988. The much greater weed biomass in the unplanted control treatments showed the importance of crop competition for weed control in sweet corn cropping systems.

The efficacy of nine granular formulations of a bioherbicide containing the fungus Sclerotinia sclerotiorum (Lib.) de Bary was determined by assessing vegetative growth from tap roots of treated plants after incubation in a controlled environment. Plants treated with formulations 0788-03 or 0788-04 did not produce new petioles and leaves from tap roots after 96 h at 23 C and 100% relative humidity.

Field experiments were conducted to compare non-phenoxy herbicides with 2,4-D for broadleaf plantain, dandelion, and white clover control in cool-season turf. Herbicides tested were BAS 514, chlorflurenol, clopyralid, dicamba, triclopyr, and 2,4-D, alone and in combinations. Broadleaf plantain was controlled by 2,4-D and by clopyralid plus triclopyr at 0.21 plus 0.63 kg ae ha-1. Dandelion was controlled by 2,4-D, BAS 514 at 0.84 kg ha-1, and by the combination of clopyralid plus triclopyr at 0.16 plus 0.47 kg ha-1. Chlorflurenol, clopyralid, dicamba, or triclopyr did not control dandelion. White clover was controlled by all herbicides except 2,4-D. The combination of clopyralid plus triclopyr was the only non-phenoxy treatment which controlled broadleaf plantain, dandelion, and white clover.

Phoma herbarum was evaluated as a potential biological control agent for dandelion (Taraxacum officinale) in turf. A preliminary controlled environment study identified selected adjuvants that enhanced disease severity by P. herbarum. Subsequently, these adjuvants were evaluated for disease enhancement under field conditions. Adjuvants evaluated included gluten flour, liposome, guar gum from ground guar (Cyamopsis tetragonoloba), durum (Triticum durum), and pectin. Regression analysis revealed a significant (P = 0.05) increase in disease severity by P. herbarum when formulated with gluten Hour, guar gum, or durum semolina compared to treatment with 20% mycelium in potato (Solanum tuberosum) dextrose broth (PDB) alone. No phytotoxicity to dandelion was observed among the adjuvant controls.