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  • Author or Editor: K.B. Perry x
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Floating rowcovers composed of extruded polypropylene, spunbonded polypropylene, and polyester were used in 1987-88 in eastern North Carolina for cold protection of strawberries (Fragaria × ananassa Duch.) growing in annual hill culture on black plastic mulch. Treatments consisted of floating rowcovers in either winter, spring, or both with and without overhead irrigation for spring frost/freeze protection, in addition to irrigated and nonirrigated unprotected plots. Winter rowcovers increased air temperatures by 1 to 2C without advancing bloom or harvest date. Significant blossom temperature differences relative to rowcover materials (≈ 1.5C) and irrigation use (≈ 1.5 to 3.0C) were detected over the course of six spring frosts. Time of application of covers (winter or spring) and irrigation in spring interacted in their effects on early yields (25 Apr.-5 May). However, rowcover and irrigation treatments did not have a significant effect on total marketable yield, yield per plant, or berry mass. In the absence of higher prices for early than late-season fruit or of more severe environmental extremes than experienced in the current study, it would be difficult to justify the added expense of rowcovers.

Free access

Abstract

A volunteer weather observing network sponsored by the North Carolina Agricultural Extension Service has been a valuable asset to horticulturists, agricultural meteorologists, and weather forecasters. Real-time temperature and precipitation data are used to assess microclimates and to compute derived parameters such as chilling hours and growing degree days. The procedures used to establish the network plus an example of its usefulness during a critical frost night are described.

Open Access

The ability of two cryoprotectants to protect tomato and pepper transplants during frost and freeze conditions was evaluated in Clayton, NC. A commercially available cryoprotectant (50% propylene block copolymer of polyoxyethylene, 50% propylene glycol, tradename FrostFree) was evaluated during 4 spring and 3 fall seasons. An antitranspirant (96% di-1-p-Menthene, i.e. Pinolene, a terpenic polymer, 4% inert, tradename VaporGard) was evaluated for 2 spring and 1 fall season. Protection from these products was not observed under the field conditions experience? Yield differences were not observed between the treated and untreated plants. With several days of cool weather preconditioning, transplants survived air temperatures of -2.0 to -1.0 C with no damage. However, with no preconditioning, damage occurred at -1.0 C without the formation of frost. At -3.5 C all plants, both treated and untreated, died. Both crops were stunted and delayed by periods of cold temperatures even when no freezing temperatures were experienced.

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The experiment screened two spring and two fall planting dates in six regions within North Carolina, South Carolina, and Georgia. The objective was to extend the production over the southeastern United States rather than at a single location. Spring harvests lasted from mid-April to early July. Summer-to-winter harvests lasted from mid-August to late January. Collards were not harvested in any of the locations from late January to mid-April or from early July to mid-August. More extensive planting dates may further increase the longevity of production.

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Four bell pepper (Capsicum annuum L.) cultivars were evaluated for yield (total weight of marketable fruit) performance over 41 environments as combinations of 3 years, three planting dates, and seven locations across North Carolina, South Carolina, and Georgia. Cultural practices, including trickle irrigation and double rows planted on black-plastic-covered beds, were uniform across all environments, except for fertilization, which was adjusted at each location based on soil tests. Comparing production over 3 years between the mountain location and the Coastal Plain location in North Carolina, yields were lower on the Coastal Plain. Spring plantings provided higher yields than summer plantings at both locations. Yield increases were obtained from hybrid cultivars over that of the open-pollinated (OP) standard [`Keystone Resistant Giant #3' (KRG#3)] in the summer planting in the mountains compared to the Tidewater Coastal Plain. Across the three-state region, hybrid cultivar yields were higher than those of the OP cultivar for the second spring planting date in 1986 and 1987. Although the hybrid yields were higher than that of the OP standard, the hybrid `Skipper' yielded less than the other hybrids (`Gator Belle' and `Hybelle'). `Gator Belle' generally out-yielded `Hybelle' at all locations, except in Fletcher, N.C. This difference may be related to the relative sensitivity of these two cultivars to temperature extremes, rather than soil or geographic factors, because there was a tendency for `Hybelle' yields to exceed `Gator Belle' in the earliest planting date. Based on the reliability index, the chance of outperforming KRG#3 (the standard) was 85% for `Hybelle', 80% for `Gator Belle', but only 67% for `Skipper'.

Free access

Abstract

‘Champion’, ‘Georgia’, ‘Heavicrop’, and ‘Vates’ collards (Brassica oleracea L. var acephala) were planted in Fletcher and Lewiston, N.C.; Charleston, Clemson, and Florence, S.C.; and Attapulgus and Plains, Ga. to determine the most reliable method to predict harvest maturity based on temperature. Although cultivar differences existed within some of the planting dates, when pooled over all planting dates, cultivars yielded similarly within locations. Eight methods of calculating heat units from planting to harvest were applied to daily maximum and minimum air temperatures supplied from local weather bureaus for the spring and fall growing seasons from 1985 through 1987 in the three-state area. Coefficients of variation were used to determine which method was most reliable in predicting day of first harvest. The method with the lowest cv was to sum, over days for planting to harvest, the difference between the daily maximum and a base temperature of 13.4C; however, if the maximum was >23.9C, the base temperature was subtracted from an adjusted maximum equal to 23.9C minus the difference between the maximum and 23.9C. This method produced a cv of 9.1% compared to 11.4% for the standard method of summing the mean temperature minus the base of 4.4C over the entire growing season, or compared to 13.4% for counting days to harvest from planting.

Open Access