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- Author or Editor: Richard B. Smith x
Strawberries (Fragaria × ananassa Duch.) cv. Redcoat were stored at several temperatures and for various intervals in controlled atmospheres (CA) containing 0% to 18% CO2 and 15% to 21% 02. Bioyield point forces recorded on the CA-stored fresh fruit indicated that the addition of CO2 to the storage environment enhanced fruit firmness. Fruit kept under 15% CO2 for 18 hours was 48% firmer than untreated samples were initially. Response to increasing CO2 concentrations was linear. There was no response to changing 02 concentrations. Maximum enhancement of firmness was achieved at a fruit temperature of 0C; there was essentially no enhancement at 21C. In some instances, there was a moderate firmness enhancement as time in storage increased. Carbon dioxide acted to reduce the quantity of fruit lost due to rot. Fruit that was soft and bruised after harvest became drier and firmer in a CO2-enriched environment.
Mechanically harvested fruit of the strawberry (Fragaria × ananassa Duch.) cv. Veeglow destined for processing can be stored at 1°C in bulk bins for 4 to 6 days if room-cooled, and for 6 to 8 days if forced-air cooled promptly after harvest, without appreciable loss due to rot development or of quality of processed product. Yields of puree from fresh fruit mechanically harvested on day 8 of the storage trial were lower than for fruit that had been forced-air cooled and stored at 0° for 8 days. Sulfur dioxide fumigation immediately after cooling reduced losses due to rot and lowered mold counts, particularly when the fruit was room cooled.
Multiple linear regression analysis was used to develop commercial harvest prediction dates for peach ‘Earlired’, ‘Redhaven’, and ‘Loring’. Prediction equations were developed using degree day summations and date of full bloom as variables. These equations were adjusted for geographic microclimatic variation and tested in 6 commercial peach orchards over 4 years. Predicted dates and actual first commercial harvest dates differed by 4 days or less for 100%, 96%, and 84% of the predictions for ‘Earlired’, ‘Redhaven’, and ‘Loring’, respectively.
Summer-grown Hydrangea macrophylla subsp. macrophylla var. macrophylla (Thunb.) were exposed for 1 week to CzH4 at 0,0.5,2.0,5.0,50, or 500 μl·liter-1 in dark storage at 16C for defoliation before cold storage. The number of leaves remaining per shoot for all cultivars decreased with C2H4 concentration, and >5 μl C2H4/liter was effective in defoliating `Kasteln', `Mathilda Gutges', and `Todi' but not `Merritt's Supreme'.
Strawberry (Fragaria ×ananassa Duch.) production in California uses plastic mulch–covered beds that provide many benefits such as moisture conservation and weed control. Unfortunately, the mulch can also cause environmental problems by increasing runoff and soil erosion and reducing groundwater recharge. Planting cover crops in bare furrows between the plastic cover beds can help minimize these problems. Furrow cover cropping was evaluated during two growing seasons in organic strawberries in Salinas, CA, using a mustard (Sinapis alba L.) cover crop planted at two seeding rates (1× and 3×). Mustard was planted in November or December after strawberry transplanting and it resulted in average densities per meter of furrow of 54 and 162 mustard plants for the 1× and 3× rates, respectively. The mustard was mowed in February before it shaded the strawberry plants. Increasing the seeding rate increased mustard shoot biomass and height, and reduced the concentration of P in the mustard shoots. Compared with furrows with no cover crop, cover-cropped furrows reduced weed biomass by 29% and 40% in the 1× and 3× seeding rates, respectively, although weeds still accounted for at least 28% of the furrow biomass in the cover-cropped furrows. These results show that growing mustard cover crops in furrows without irrigating the furrows worked well even during years with relatively minimal precipitation. We conclude that 1) mustard densities of ≈150 plants/m furrow will likely provide the most benefits due to greater biomass production, N scavenging, and weed suppression; 2) mowing was an effective way to kill the mustard; and 3) high seeding rates of mustard alone are insufficient to provide adequate weed suppression in strawberry furrows.
Celery (Apium graveolens L. var. dulce DC.) stored at 0°-1°C in 1.5% O2 had better marketable quality than that stored in air after 11 weeks. Marketable celery was improved by using 2.5-7.5% CO in the storage atmosphere, but not by 2-4% CO2. Decay was most severe on celery stored in 21% O2. Botrytis cinerea Pers. and Sclerotinia sclerotiorum (Lib.) de Bary were the most frequent isolates recovered from decayed celery.
Total weight loss of < 10% over a 10-week period was achieved by storing celery in atmospheres containing 1% O2 combined with 2% or 4% CO2 at 0°C. Significant increases in marketable celery resulted when C2H4 was scrubbed from some atmospheres. A combination of 1% or 2% O2 and 2% or 4% CO2 prevented black stem development during the storage period. Improved visual color, appearance, flavor, and increased marketable celery justifies the use of 4% CO2 in celery storages.
Sclerotinia sclerotiorum (Lib.) de Bary and Botrytis cinerea Pers. were highly pathogenic to celery stored at 0° to 1°C in normal air (21% O2). Alternaría dauci (Kuhn) Groves & Skolko, Rhizopus nigricans Ehrenb., Penicillium sp., and Fusarium oxysporum Schlecht, were nonpathogenic. An atmosphere of 7.5% CO/1.5% O2 was more suppressive to disease caused by B. cinerea and S. sclerotiorum than low 1.5% O2 atmosphere alone. The 4% CO2/1.5% O2 and 0.0003% C2H4/1.5% O2 atmospheres were slightly suppressive to disease caused by S. sclerotiorum only. The 7.5% CO/1.5% O2 atmosphere also was consistently suppressive to mycelial growth, spore germination, and germ tube elongation of B. cinerea.
Small-scale vegetable farmers are interested in cover crops and reduced tillage, but scale-appropriate technology and equipment are necessary to expand these practices to the growing segment of small farms. We sought to determine the efficacy of tarps, an increasingly popular tool on small farms, to end overwintering cover crops and provide weed suppression for subsequent no-till cabbage production. In three fields over two seasons in Maine, we grew a winter rye (Secale cereale L.) and hairy vetch (Vicia villosa L.) cover crop, which we managed by a factorial combination of tillage (no-till, till) and tarping (tarp, no-tarp) in June, followed by a transplanted cabbage crop (Brassica oleracea L. var. Capitata) in July. Within each treatment, subplots were either weeded by hand or left unweeded. Cover crop biomass ranged from 2.8 to 4.5 Mg⋅ha−1. Mean cabbage weights in the novel no-till system (no-till/tarp) were greater than (year 1) or equal to (year 2) those in tillage-based systems (till/no-tarp and till/tarp). In year 1, the mean cabbage weight in weeded subplots was 48% greater in no-till/tarp than in till/no-tarp systems. In unweeded subplots, this difference was 270%, highlighting the efficacy of the no-till/tarp system to reduce the impact of weeds. In year 2, weed biomass was higher with all treatments than it was in year 1, and unweeded subplots failed to produce marketable heads (i.e., >300 g). The mean cabbage weight in weeded subplots was equal among no-till/tarp, till/tarp, and till/no-tarp systems. Tarping had a strong effect on weed biomass and weed community composition measured at the time of cabbage harvest in unweeded subplots. In year 1, weed biomass at the time of cabbage harvest with tarp treatments was less than half that with no-tarp treatments. Tarps effectively facilitated the cover crop mulch-based no-till system. We propose that this system is an adaptive strategy for farmers affected by climate change. However, both cover crop production and tarping shorten the growing season. We discuss tradeoffs and opportunity costs using the metric of growing degree days.