Basic meteorology as it applies to frost-freeze events and a discussion of the methods of frost protection are included in this article. The presentation of basic meteorology includes descriptions of heat transfer, energy exchange, inversion, frost, freeze, microclimate, air versus crop temperature, and forecasts and warnings in the context of how each of these in involved in frost-freeze events. The second part of the paper describes the major methods of frost protection for commercial crops. The methods included are site selection, irrigation (overhead, undercanopy, man-made fog, flooding), wind machines, heaters, covers, and sprayable materials.
Katharine B. Perry
Katharine B. Perry and Todd C. Wehner
A heat unit model developed in a previous study was compared to the standard method (average number of days to harvest) for ability to predict harvest date in cucumber (Cucumis sativus L.). Processing and fresh-market cucumbers were evaluated in 3 years (1984 through 1986), three seasons (spring, summer, and fall), and three North Carolina locations. The model predicted harvest date significantly better than the standard method for processing, but not for fresh-market cucumbers.
Katharine B. Perry and Todd C. Wehner
The use of a previously developed model for predicting harvest date in cucumber production systems is described. In previous research we developed a new method using daily maximum temperatures in heat units to predict cucumber harvest dates. This method sums, from planting to harvest, the daily maximum minus a base temperature of 60F (15.5 C), but if the maximum is >90F (32C) it is replaced by 90F minus the difference between the maximum and 90F. This method was more accurate than counting days to harvest in predicting cucumber harvest in North Carolina, even when harvest was predicted using 5 years of experience for a particular location and planting date.
Katharine B. Perry, A. Richard Bonanno and David W. Monks
A commercially available cryoprotectant (50% propylene block copolymer of polyoxyethylene, 50% propylene glycol; trade name FrostFree) and an antitranspirant (96% di-1-p-menthene, i.e., pinolene, a terpenic polymer, 4% inert; trade name Vapor Gard) were evaluated for their ability to protect `Pik Red' tomato (Lycopersicon esculentum Mill.) and `Keystone Resistant Giant #3' pepper (Capsicum annuum L.) plants during frost and freeze occurrences in the field. Tests were conducted during four spring and two fall seasons. Protection from these products was not observed under field conditions when minimum air temperature reached -3.5C and -l.0C on separate occasions. Yields for treated and untreated plants were similar. Neither cryoprotectant injured the foliage in the absence of cold events.
Katharine B. Perry, Rodger R. Getz and H. Ray Kimsey Jr.
Access to weather information for planning and implementing horticultural practices is an important component of the production system for growers. Advances in meteorological instrumentation, data acquisition and storage, and communications technologies have improved greatly the potential for applying sophisticated weather information into daily on-farm decisionmaking. The North Carolina Agricultural Weather Program seeks to provide weather information to the horticultural interests of the state. It has developed over the past 13 years. Recently, budget reductions near 50% and the loss of two-thirds of the extension full-time equivalents have necessitated significant changes. Through regional cooperation and the use of electronic communications technology, the program has sustained these negative impacts and emerged as an improved program. This paper describes the evolution of a state agricultural weather program into what is now a regional cooperative project to provide the weather information horticultural producers require.
Robert J. Dufault, K. Dean Batal, Dennis Decoteau, J. Thomas Garrett, Darbie Granberry, Wayne McLaurin, Russell Nagata, Katharine B. Perry and Douglas Sanders
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.
Laurie Hodges, Douglas C. Sanders, Katharine B. Perry, Kent M. Eskridge, K.M. `Dean' Batal, Darbie M. Granberry, Wayne J. McLaurin, Dennis Decoteau, Robert J. Dufault, J. Thomas Garrett and Russell Nagata
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'.