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Carolyn J. DeMoranville

In Massachusetts, cranberry (Vaccinium macrocarpon) bogs were historically developed in existing wetlands and new plantings are now established in mineral soils that are converted into constructed wetlands. To streamline the interaction between cranberry farming and wetlands protection, the state has defined “normal agricultural practices” that are exempt from wetlands regulations under certain circumstances. As part of that process and to qualify for the exemption, farmers are required to have a conservation farm plan and demonstrate the use of best management practices (BMPs) on their farms. The University of Massachusetts Amherst Cranberry Experiment Station (UMass Cranberry Station) was engaged to bring together the U.S. Department of Agriculture, Natural Resource Conservation Service (NRCS) and cranberry industry representatives to define BMPs specific to cranberry farming practices. Initially, the documents were reviewed by scientists and regulators for soundness of science and rigor of environmental protection. A grower committee reviewed the proposed BMPs to determine if the BMPs could be implemented on real farms. The next stage of the project consisted of defining areas where more research was needed to formulate good BMPs. In particular, research projects were initiated to study nitrogen and phosphorus nutrition. This research has become the basis for nutrition BMPs, national cranberry nutrition guidelines, and standards used by NRCS for cranberry nutrient management plans. The cranberry BMP project has continued with a regular cycle of revision and additions based on grower-identified needs for horticultural and environmental guidance. This connection to the growers, along with the regulatory link, accounts for the widespread adoption of BMPs in the cranberry industry. Local NRCS estimates that 75% to 80% of Massachusetts cranberry growers have current conservation farm plans that include BMP implementation.

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Carolyn DeMoranville, Irving DeMoranville, and Tom Bicki

Cold tolerance of cranberry (Vaccinium macrocarpon Ait.) flower buds (spring) and fruit had previously been investigated for the cultivars Early Black (EB) and Howes (H), leading to predictors of cold tolerance based on appearance of the buds (size and growth) and fruit (color). We studied these cultivars along with `Ben Lear' (BL) (buds only) and `Stevens' (S) using controlled temperatures to determine the accuracy of predicting cold damage. BL was the least cold-tolerant cultivar in early spring, both BL and S were less tolerant than EB and H during budbreak (-2.8C vs. -3.9C) and elongation (-2.8C vs. -1.4C), and all survived any exposure to -1.4C. EB fruit were tolerant of -5C once maximum color was achieved and 2 weeks later would tolerate short exposures to -6.5C or less. H fruit developed deep tolerance (below 6.5C) by November in only 1 year out of 2. S fruit were least tolerant: -5C for short periods at M maturity. The phenological model used to predict cold tolerance of flower buds was 48% accurate in our trials, generally overestimating bud tolerance, particularly for BL and S. EB fruit showed more tolerance than predicted, H less.

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Joan R. Davenport and Carolyn DeMoranville

Soluble nitrogen (ammonium and nitrate) is released when soil organic matter is mineralized. The amount of N released by this process depends on the amount of organic matter present and soil temperature. Cranberry (Vaccinium macrocarpon Ait.) grows in acidic soils with a wide range in organic matter content. To evaluate how soil N release is affected by soil temperature, intact soil cores were collected from sites that had received no fertilizer and placed in PVC columns. Four different soil types, representing the range of cranberry soils (sand, sanded organic soil, peat, and muck), were used. Each column was incubated sequentially at six different temperatures from 10 to 24 °C (2.8 °C temperature intervals) for 3 weeks at each temperature, with the soils leached twice weekly to determine the amount of N release. The total amount of N in leachate was highest in organic soils, intermediate in the sanded organic soil, and lowest in the sands. The degree of decomposition in the organic soils was important in determining which form of N predominated. In the more highly decomposed organic soil (muck), most of the N was converted to nitrate. The data from this study resulted in the development of two models—one predicting the N mineralization and the other predicting the proportion of N in each of the two forms. Key factors for N release rate were soil temperature, percentage of clay, and organic carbon content. For predicting the proportion of N as ammonium vs. nitrate, key factors were soil temperature, soil pH, and the distribution of mineral matter in the silt and sand fractions.

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Joan R. Davenport and Carolyn DeMoranville

Native nitrogen is released when soils are mineralized. The amount of N released by this process depends on the amount of organic matter present and soil temperature. Cranberry (Vaccinium macrocarpon Ait.) grows in acidic soils with a wide range in organic matter content. To evaluate release of cranberry soil N at varied soil temperatures, intact soils were collected from sites that had received no fertilizer. Soils were cored and placed in polyvinyl chloride (PVC) columns 20 cm deep × 5 cm in diameter. Four different soil types, representing the array of conditions in cranberry soil (mineral, sanded organic, organic peat, and muck) were used. Additional columns of sand soil (pH 4.5) that had been pH adjusted to high (6.5) and low (3.0) were also prepared. Each column was incubated sequentially at six different temperatures from 10 to 24 °C (2.8 °C temperature intervals) for 3 weeks at each temperature, with the soils leached twice weekly to determine the amount of N release. The total amount of N in leachate was highest in the organic soils, intermediate in the sanded organic, and lowest in the sands. At the lowest temperature (10 °C), higher amounts of N were released in sanded organic and sand than in organic soils. This was attributed to a flush of mineralization with change in the aerobic status and initial soil warming. The degree of decomposition in the organic soils was important in determining which form of N predominated in the leachate. In the more highly decomposed soil (muck), most of the N was converted to nitrate. In the pH adjusted sand, high soil pH (6.5) resulted in an increase in nitrate in the leachate but no change in ammonium when compared to non-adjusted (pH 4.5) and acidified (pH 3.0) treatments. This study suggests that for cranberry soils with organic matter content of at least 1.5% little to no soil-applied fertilizer N is needed early in the season, until soil temperatures reach 13 °C. This temperature is consistent with the beginning of active nutrient uptake by roots. Soil N release from native organic matter was fairly consistent until soil temperatures exceeded 21 °C, indicating that when temperatures exceed 21 °C, planned fertilizer applications should be reduced, particularly in highly organic soils.

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Carolyn DeMoranville, Anne Averill, and Martha Averill

In commercial cranberry (Vaccinium macrocarpon Ait.) production, flooding is used as a cultural practice for harvest and for winter protection. In addition, after the withdrawal of the winter flood, cranberry bogs may be reflooded in the spring, a practice known as holding “late water” (LW). This practice was used by early cranberry growers in Massachusetts to avoid spring frost and to promote keeping quality in the harvested fruit. Recently, LW has been “rediscovered” as a cultural tool with the potential for reducing inputs of chemical pesticides and fertilizers. We have begun to document the effects of LW on pest populations and on cranberry plants to provide growers with a solid basis for deciding whether to use this cultural practice. In 1993, 11 LW bogs were studied and compared to control bogs. All of the bogs showed acceptable levels of insect and disease damage on the fruit at harvest. The average number of pesticide applications for the LW bogs vs. controls was 0.9 vs. 2.6 for insecticides and 1.3 vs. 2.8 for fungicides.

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Carolyn J. DeMoranville and Joan R. Davenport

It has been speculated that cranberries are susceptible to chloride injury. If this is the case, it is possible that applications of high rates of 0-0-60 (KCl) fertilizer as a K source could be detrimental to cranberry productivity. Grower anecdotes of using 0-0-60 to “shut down the plants” persist. Supposedly, using 225+ kg·ha-1 of this material slows or arrests vegetative growth. In fact, growers have claimed it can overcome the production of rank vegetation that results when too much N fertilizer has been applied. Field plots were initiated to determine the suitability of KCl and to determine if high K rates could overcome the deleterious effects of excess applied N. Plots were set up in a split-block plot design with N doses [three each “normal” (28-34 kg·ha-1 N) vs. “high” (56-67 lb N/A)] in one direction and potassium/chloride treatments in the other direction (KCl or K2SO4 at 115 or 225 kg K2O; CaCl2 to give the equivalent Cl as in the high-rate KCl treatment, and a nontreated control) for a total of 36 2 × 2-m plots per each of three cultivar locations. Plots were treated and evaluated for three consecutive years. There were no significant differences in yield among the K2SO4 and KCl treatments, indicating that at rates as high as 225 kg·ha-1 K2O, 0-0-60 and 0-0-50 perform similarly. Further, treatment with CaCl2 had no significant effect on yield. In the third year, plots receiving no K treatment had significantly lower yield than those receiving either rate or form of K (single degree of freedom comparison, significant at 0.03). These results indicate that at the rates used in this study, KCl is an adequate K source. The effect of N rate was more pronounced than that of the K treatments. In years two and three, the low N rate strips had significantly greater yield compared to that in the high N rate strips. By year two, the high N strips were visually different, with rank overgrowth. There was no significant interaction of N rate and the K treatments. While there was a trend for greater difference between the 0 K and 115 kg K rates in the high N plots compared to the moderate N plots, the addition of K never entirely overcame the negative yield effects of high N rate.

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Justine E. Vanden Heuvel and Carolyn J. DeMoranville

Competition between reproductive and vegetative growth has not been studied in cranberry. The objective of this research was to assess the growth patterns of leaves and fruit in three cranberry cultivars to determine whether vegetative and reproductive growth compete for resources. ‘Stevens’, ‘Howes’, and ‘Early Black’ uprights and fruit were collected on a weekly basis in 2002 and on a biweekly basis in 2003 and 2004 from a research bog in Massachusetts. Although growth was affected by cultivar and year, data indicated a general shifting of resource allocation from leaf area and dry weight accumulation to fruit growth at ≈1500 growing degree days (GDD, base 4.4 °C), when the initial surge of fruit growth began. Leaf area and dry weight accumulation resumed at ≈2300 GDD, resulting in a competition for resources with the developing fruit until after 3000 GDD. A lag phase in fruit diameter and dry weight accumulation was noted in some years and some cultivars and may be partially the result of the resumption of leaf growth at 2300 GDD. Fruit and shoot growth appear to compete for resources in late July through early August in Massachusetts, when carbohydrate concentration of uprights and roots is extremely low.

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Justine E. Vanden Heuvel and Carolyn J. DeMoranville

Competition between fruit and upright growth in cranberry has not been previously studied, but negative correlations reported between upright length/dry weight and yield indicate that sink demand from vegetative tissues may reduce fruit production. `Stevens', `Howes', and `Early Black' uprights and fruit were collected on either a weekly or bi-weekly basis through the growing seasons of 2002–04. The data indicated a shifting of resource allocation from leaf area and dry weight accumulation to fruit growth when about 1500 growing degree days (GDD, base 4.5 °C) had accumulated. Following the initial surge in fruit growth, leaf area and dry weight accumulation resumed at roughly 2300 GDD, resulting in a competition for resources with the developing fruit until after 3000 GDD. A lag phase in fruit diameter and dry weight accumulation was noted in some cultivars in some years, and may be partially due to the resumption of leaf growth. Roots, uprights, and fruit may all compete for resources during the hottest portion of the growing season.

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Carolyn DeMoranville, Anne Averill, and Joan Davenport

The two major determinants in sustainable cranberry production are productivity and preservation of water quality. Productivity and water quality were studied using composted chicken manure (CM) and fish hydrolysate fertilizer (FH). In whole bog field trials, soluble granular fertilizer (SG) was replaced with organic fertilizer. At all locations receiving FH, cranberry yields were maintained or improved. The yield results from bogs receiving the CM were mixed, partially due to the quality of the experimental sites. Based on water samples taken from bogs receiving FH, there was no P output and less NH output than from bogs receiving SG. Leaching properties of CM, FH, and SG in cranberry soils were investigated in the laboratory. Concentrations of N03 -, P04 -, and K+ were greatest in the leachate from columns receiving SG, indicating that organic fertilizers are less likely to lead to the leaching of nutrients into cranberry bog water.