With dwindling funding for horticultural research, the need to conduct experiments which are the most efficient in terms of resource (including personnel) utilization becomes apparent. Research on minor crops such as cranberry (Vaccinium macrocarpon, Ait.) has been particularly hard-hit by the funding crunch. A study to generate a large database as the basis for future experimental design was initiated in 1986 for the variety `Early Black' (60% of MA commercial acreage). Seasonal nutrient levels for all tissues, patterns of biomass development, components of yield, and fruit development were included. In 1989, the study was expanded to include a comparison of 6 MA varieties grown under the same cultural and environmental condition. A portion of the database will be presented and its implementation to increase field experiment efficiency will be discussed.
Productivity in cranberry plots receiving either fish hydrolysate fertilizer or inorganic soluble fertilizer at the same dose has been studied for the past three seasons. In the past two seasons, fish hydrolysate fertilizer (produced from cod frames and stabilized with phosphoric acid) has been used experimentally on a commercial scale. Both series of experiments lead to the conclusion that fish hydrolysate is an acceptable alternative to soluble fertilizer for cranberries. In fact, fish hydrolysate will be included in the University fertilizer guidelines for cranberries to be issued in the spring of 1990. The evidence will be presented along with the arguments in favor of the use of this organic-type material. Continuing lines of research which may lead to increased grower acceptance will be outlined.
An extensive study (276 samples) was conducted in 1960 to correlate cranberry (Vaccinium macrocarpon, Ait.) bog soil pH and productivity (Chandler, F. B. and Demoranville, I. E. 1961. Cranberries 26(3):9-10). At that time, soil pH averaged 4.37 and excellent productivity was represented by a yield greater than 10 mT/ha. Thirty years later, when more than 28 mT/ha is considered good yield, soil samples will be collected from these same sites and evaluated for pH by the methods used previously. Production records for the pact three years will be obtained and the average value for each location used to construct a regression of bog yield vs soil pH. Information presented will include: 1. productivity vs soil pH in 1960 and 1990; 2. change in soil pH after 30 years?; 3. possible reasons for changes-if any (grower interviews); 4. implications for the future.
Commercial cranberry (Vaccinium macrocarpon Ait.) soils are high in iron and calcium and have low pH. This soil chemistry causes conditions where phosphorus is tightly bound and is, to a large extent, unavailable to the cranberry plants. In theory, P forms that directly enter the plant (foliar), or that do not quickly dissolve to become rapidly immobilized (organic, slow-release, other insoluble forms) could be more efficient for cranberry production. To test this hypothesis, two separate sets of field plots, one comparing 19 kg P/ha from sole P sources (all received 22 kg·ha–1 each N and K2O as ammonium sulfate and potassium sulfate) and the other comparing “complete” N–P–K fertilizers containing P, were established at six locations on three cranberry cultivars. Experiment #1 showed that, over all locations, there were no differences in mean yield for plots fertilized with triple super phosphate (current practice), foliar, or rock phosphate. However, fruit rot levels differed by treatment. In Experiment #2, organic forms (except bone meal) gave the lowest yields, while rock phosphate plots had the greatest yields. These field studies indicated that, while some organic P sources may not be suitable for cranberry production, low-leaching P forms such as bone meal and rock phosphate were as effective for cranberry production as the more-soluble triple super phosphate.
Extensive study of the use of late water (LW, a 4-week spring flood used to control pests) in modern cranberry production systems began in 1993, focused on the effects of the flood on pests and the cranberry plants, and compared LW to companion early water (EW, no spring flood) bogs and to their own histories. In 1993 and 1994, LW bogs had yields comparable to EW controls with N fertilizer reductions of 35% and 60%. In the year following LW, N use returned to pre-LW levels. In 1995, N use was reduced by 65%. However, yield on LW bogs was reduced in 1995, at least in part due to anomalous winter weather and drought. Upright length and density did not differ between LW and EW bogs (1993–95). This may have been due to reduced N dose offsetting any growth-promoting effects of LW. In 1994 and 1995, LW bogs had fewer flowers than EW bogs, but increased fruit set compensated in 1994. LW may adversely affect yield in some years but this could be offset by reduced production costs or increased yields in following years. Cost/return budgets are being studied.
The american cranberry (Vaccinium macrocarpon) is a wetland plant native to North America. The plant is adapted to sandy, nutrient-poor, low pH soils and thus, like blueberry (Vaccinium sp.), its nutritional requirements are low compared with many other perennial fruit crops. Research conducted over the past 30 years has defined the annual requirements for nitrogen [N (20–60 lb/acre)], phosphorus [P (<20 lb/acre)], and potassium (40–120 lb/acre) based on tissue testing, plant growth demands, potential for remobilization, and determination of removal in the crop. These three nutrient elements are those most commonly applied to the crop in fertilizers. However, much of the work on nutrient rate requirements was conducted on native cultivars and there is an expectation that requirements of newer hybrid cultivars are greater. In Massachusetts, cranberries are grown in coastal watersheds and often depend on small lakes as their water source for irrigation, harvest, and winter flooding. Since cranberry production is heavily dependent on water use, the interaction of nutrient management and water management has become a primary focus area for research and extension, particularly for N and P, the nutrient elements most frequently associated with environmental pollution. Recent preliminary research examining cranberry farms with varied configurations (e.g., water passes through the bog and exits via a long channel, water recirculates back into the supply water body) has indicated that the cranberry bogs may act as either a source or sink for N depending on configuration and management activities. In a study of cranberry farms where P use was reduced to an average of <10 lb/acre, P concentration in harvest flood water declined by as much as 85% while crop production was sustained. Site variation in output of N and P in cranberry drainage and flood waters indicates the need for further research into the variables that control these processes, including soil types, site hydrology, nutrient application rates and forms, and water-management activities.
Carolyn DeMoranville and Irving Demoranville
Cold tolerance of cranberry flower buds from four cultivars was evaluated using potted sods collected from commercial cranberry beds. The plants were evaluated weekly beginning at the spring dormant stage and continuing until the buds had elongated to at least 2 cm. The potted plants were place in controlled temperature chambers at 5°C and the temperature was lowered 3°C/hr until the target temperature was reached. The plants were held at that temperature for 3 hr then slowly warmed. After 24 hr, damage was evaluated by microscopic examination of cross-sectioned buds. In the early spring, prior to leaf greening, all four cultivars were tolerant of –8°C. In the later part of the spring, cultivars with the smallest buds had greater cold tolerance than those with larger buds. Even when all cultivars appeared to be at the same developmental stage, e.g., bud swell, `Ben Lear' and `Stevens', were more sensitive than `Early Black' and `Howes'. At the 2-cm elongation stage, minimum cold tolerance of –1°C was reached for all four cultivars. New recommendations for protecting cranberry flower buds in the spring have been formulated based on this study.
Carolyn DeMoranville and Anne Averill
Cranberry tipworm (Dasyneura vaccinii Smith) lays its eggs in the upright tips of cranberry (Vaccinium macrocarpon Ait.) plants. Feeding damage by newly hatched maggots leads to characteristic cupping of leaves in the upright tip. This damage is readily apparent to growers and has led to concern that damaged tips would not form terminal flower buds for the following season. Insecticide sprays and cultural practices intended to control this insect are generally ineffective. While studying the incidence of return bloom in cranberry uprights (Strik, B. C., et al. 1991. HortScience 26:1366-1367) heavy cranberry tipworm injury with little apparent effect on yield was noted. We initiated a three year study to examine the potential for cranberry plants to recover from tipworm injury and found that cranberry plants recover completely (no effect on flower bud production) from tipworm injury as long as the injury occurs before mid-August. Only 25% recovery from late-season infestations was found. However, such infestations seldom affected more than 5% of the upright tips. Based on our data, we calculated a maximum 6% loss of flower buds to cranberry tipworm in a year of high late-season infestations.
Carolyn DeMoranville and Joan Davenport
The relationship between yield and applied N in cranberry has been investigated. Cultivar was important in determining optimum seasonal N rate. Sustained production for the hybrid `Stevens' required an annual seasonal total of N at up to 67 kg·ha–1, higher than was optimal for native selections `Early Black' and `Howes'. High N rates were associated with increased fruit rot and vine overgrowth. Optimum N rate varied within cultivar, likely due to variation in soil conditions, but soil N test results have not correlated well with subsequent yield in cranberry. Soil organic matter content can predict potential N release, but plant response must also be taken into account. To refine N rate recommendations, plant characteristics that might predict N requirements/status of cranberry were investigated. A standard of 0.9% to 1.1% N in August tissue has been established for cranberry. To find characteristics that could be used earlier, we surveyed 30 sites for percentage of N in tissue, length of new growth, SPAD chlorophyll meter ratings, fertilizer N use, and yield. Length of new growth could be used as an indicator of cranberry N status from June until bloom, being positively correlated with subsequent yield. The SPAD meter proved to be a viable alternative to in-season monitoring of tissue N during June and July. Readings below proposed standard values indicated the need for N fertilizer if vegetative growth was in the standard range. Thus, the easily determined factors of upright length and SPAD rating could be used to refine fertilizer rates during the active growing season, while tissue testing for percentage of N could be used as a “report card” on the fertilizer program at the end of the season.
Carolyn J. DeMoranville
Levels of major elements (N, P, K, Mg, Ca) in `Early Black' cranberry (Vaccinium macrocarpon Ait.) tissues changed during the season (April to October). A distinct pattern was associated with each tissue type (old leaves, woody stems, new shoots, roots, fruit) and each element. However, the pattern for a given element in a given tissue was similar from year to year. For example, nitrogen levels in old leaves rose early in the season and then declined in old leaves as new shoot tissue was produced. The early-season rise in nitrogen levels in old leaves coincided with a decline in nitrogen in woody stem tissue. Changes in the amount of applied nitrogen led to changes in nitrogen levels in new shoots after a 2 year Iag. While N, K, Ca, and Mg content (% dry weight) in roots is lower than that in other tissues, there is great biomass of root tissue, so that root tissue represents a large pool of these elements. Roots, along with woody stems and old leaves may represent a reservoir of major elements for new shoot development early in the season, prior to fertilizer application. Levels of the major elements in new shoot tissue achieved a steady state in August, an indication that this is a good time to collect tissue for routine testing.