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Ed Kee, Tracy Wootten, James Adkins, and James Glancey

Proper variety selection and production practices are critical to obtaining profitable yields of mechanically harvested pickling cucumbers (Cucumis sativus L.). On the Delmarva peninsula, the tractor-mounted harvester, which utilizes the pinch-roller system for separating the pickles from the vine, was used exclusively for harvest until 1998. The pull-type forced-balance shaker machines have been introduced as an alternative harvest system. Replicated commercial-size variety trials have been conducted for four consecutive years. The trials are planted twice during the growing season, reflecting the climactic differences associated with early-season and late-season plantings. `Vlaspic' and `Lafayette' are standard varieties. Promising new varieties include `EX 1914' and `SQRP 1882'. Investigations to determine optimum plant populations and row spacing have determined that three-row beds with 60,000 plants per acre provide the highest yields and best quality fruit. Optimal operating speeds and picking reel speeds of 1.4 mph and 45 rpm, respectively, have been determined for the tractor-mounted machine. Additional design improvements have been implemented and evaluated to reduce damage. Fifty-nine replicated commercial tests evaluating the tractor-mounted harvester and the forced-balance shaker type indicate much greater harvest and throughput efficiencies are associated with the forced-balance shaker harvester, resulting in improvements between $65 and $100 per acre.

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James Sellmer, Craig R. Adkins, Ingram McCall, and Brian Whipker

Plant growth retardant (PGR) substrate drenches (in milligrams active ingredient) of ancymidol at 0.25, 0.5, 1, 2, or 4; paclobutrazol at 1, 2, 4, 8, or 16; and uniconazole at 0.25, 0.5, 1, 2, or 4 were applied to pampas grass (Cortaderia argentea Nees) to compare their effectiveness at chemical height control during greenhouse forcing and evaluate the residual effect on plant growth in the landscape. Cortaderia argentea plant height exhibited a quadratic dose response to paclobutrazol and uniconazole, while ancymidol-treated plants showed a linear dose effect. During greenhouse production, all rates of uniconazole reduced plant height by 56% to 71% compared to the untreated control, whereas paclobutrazol and ancymidol treatments reduced plant height by 14% to 61% and 0% to 34%, respectively. Severe height retardation was evident at 2 mg of uniconazole. By week 5 in the field all plants treated with uniconazole, paclobutrazol doses of 4, 8, or 16 mg, and with 4 mg of ancymidol were shorter than the untreated control. By week 24 in the field, all plants exhibited similar heights except plants treated with uniconazole at 1, 2, or 4 mg remained shorter than the untreated control. In conclusion, each PGR was effective in controlling plant height of Cortaderia argentea during greenhouse forcing. Furthermore, plants treated with low to moderate rates of ancymidol or paclobutrazol grew out of the regulating effect by week 5 in the landscape. These results demonstrate that PGR can be effectively and economically employed in the production of Cortaderia argentea.

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James C. Sellmer, Craig R. Adkins, Ingram McCall, and Brian E. Whipker

Plant growth retardant (PGR) substrate drenches (in mg a.i per pot.) of ancymidol at 0.25, 0.5, 1, 2, or 4; paclobutrazol at 1, 2, 4, 8, or 16; and uniconazole at 0.25, 0.5, 1, 2, or 4 (28,350 mg = 1.0 oz) were applied to pampas grass (Cortaderia selloana). Control of height growth during greenhouse forcing and the residual effects on plant growth in the landscape were evaluated. During greenhouse forcing, plant height exhibited a quadratic dose response to paclobutrazol and uniconazole, while ancymidol treated plants exhibited a linear response to increasing dose. All rates of uniconazole resulted in plant heights which were 56% to 75% shorter than the nontreated control, whereas paclobutrazol and ancymidol treatments resulted in 6% to 64% and 5% to 29% shorter plants, respectively. Severe height retardation was evident with {XgtequalX}2 mg uniconazole. When the plants were transplanted and grown in the landscape (24 weeks after the PGR application), all plants treated with ancymidol, paclobutrazol, and {XltequalX}0.5 mg uniconazole exhibited heights similar to the nontreated control, suggesting no residual effects of the PGR for these treatments. Only plants treated with uniconazole at {XgtequalX}1 mg remained shorter than the nontreated control in the landscape. These results demonstrate that plant growth regulators can be effectively and economically applied in the greenhouse production of pampas grass.