Solarization and chemical alternatives to methyl bromide (MeBr) soil fumigation for strawberry (Fragaria {XtimesX}ananassa) were evaluated in a 3-year study in Savannah, Ga. Solarization using clear or black plastic, metam sodium (Sectagon), dazomet (Basamid), 1,3-dichloropropene and chloropicrin (Telone C-35), MeBr, and untreated control treatments were used. Solarization produced maximal soil temperatures of 55 to 60 °C (131 to 140 °F) at the 2.5 cm (1 inch) depth, and 42 to 48 °C (108 to 118 °F) at the 15 cm (6 inch) depth. Clear and black plastic were generally equally effective in heating the soil. A double layer of clear plastic raised soil temperatures 1 to 2 °C (2 to 4 °F) above those under a single layer of clear at the 2.5 cm depth, although this occurred less frequently at the 15 cm depth. MeBr treatment increased yield by 46% and 128% in the first and second years, respectively, compared to the untreated control, but all treatments were similar in yield in year three. Season average fruit size differed among treatments in only the first year, with MeBr resulting in fruit 13% to 25% larger than other treatments. Yield for the metam sodium treatment in the first year was 34% lower than for MeBr, but comparable to MeBr in the other 2 years. Solarization treatment yields were similar to those of MeBr in the first and third years, but could not be analyzed in the second year due to plot damage. Dazomet treatment yields were similar to those of MeBr, metam sodium, and the untreated control in its single year of testing, but logistics of application and high costs may disfavor this treatment. The 1,3-dichloropropene/chloropicrin treatment performed as well as MeBr in its single year of testing. Three treatments-metam sodium, 1,3-dichloropropene/chloropicrin, and solarization with black plastic-offer viable, lower cost alternatives to MeBr.

A 3-year study on the effects of growth stimulants on yield, bulb size, bulb quality, and storability of short-day onions (Allium cepa L.) was conducted at three locations. Treatments included 2-hydroxypropanoic acid, humic acids, humic acids in conjunction with micronutrients, and two formulations of cytokinin applied as a transplant dip and/or plant spray. There were no differences between 2-hydroxypropanoic acid and an untreated check at two different farm locations for onion yield, equatorial bulb diameter, or percent jumbos [≥3 inches (≥7.6 cm)] in 1997. Comparisons between untreated checks, 2-hydroxypropanoic acid, humic acids as a transplant dip or plant spray, and humic acids with micronutrients, all applied as transplant dip or plant spray, indicated there were no differences among treatments for yield, pungency, soluble solids, equatorial bulb diameter, or percent marketable bulbs after 6 months in controlled atmosphere storage in 1997-98. In a final experiment, these treatments were evaluated in a factorial arrangement using the short-day onion cultivar Pegasus and a mixture of cultivars WI-609 and WI-3115, which are referred to as Wannamaker cultivar mix. `Pegasus' displayed higher yield and lower soluble solids than the Wannamaker cultivar mix. Treatment with humic acids and micronutrients, or cytokinins resulted in greater percent marketable bulbs after 4.5 months of controlled atmosphere storage compared to the untreated check. No differences were observed among the treatments for pungency or bulb size. In addition, there was no treatment by cultivar interaction.

No abstract

The effect of cooling method and duration on off-season cut flower production of Lysimachia clethroides Duby was examined. Rhizomes harvested in October were cooled for 0, 4, 6, 8, 10, or 12 weeks at 4 ± 1 °C in crates with unmilled sphagnum peat moss or in 3.75-L pots filled with a commercial soilless medium prior to forcing in a warm greenhouse. After 6 or more weeks of cooling, shoots emerged from crates in higher percentages than from pots. However, only the duration of cooling, not the method, affected the rate of shoot emergence, visible bud formation, and anthesis of the first bud in the raceme. As cooling increased from 0 to 12 weeks, the greenhouse days required for shoot emergence, visible bud formation, and anthesis decreased linearly. The number of flowering flushes and flowering stems produced per plant varied quadratically with cooling duration, and the highest yields occurred when rhizomes received between 4 and 10 weeks of cooling. High numbers of flowers were produced rapidly after 10 weeks of cooling. As the number of successive flowering flushes increased, the stem length increased linearly while the stem diameter decreased linearly.

Pelargonium×hortorum L.H. Bailey `Scarlet Elite' seedlings were grown in plugs from seed to transplant size. About 14 days before attaining transplant size, seedlings were exposed to various fertility or temperature regimes (preconditioning treatments), then stored for 1 to 3 weeks at 5C. Seedlings receiving 150 mg N/liter before storage flowered sooner and required less crop time (days to flower – days in storage) than those receiving 0, 75, or 300 mg. Temperature preconditioning at 10 or 15C delayed flowering compared to preconditioning at 20C. Final plant height and dry weight were not adversely affected by varying N levels or temperature during preconditioning. Preconditioning seedlings with 300 mg N/liter resulted in seedling mortality rates up to 16% after 7 days' storage. Low temperature or fertility were not effective preconditioning treatments. Best results were attained by preconditioning seedlings with 150 mg N/liter.