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Michael A. Norman, Kim D. Patten, and Sarangamat Gurusiddaiah

Three indicator species [rye (Secale cereale L.), radish (Raphanus sativus L.), and alfalfa (Medicago sativa L.)] and nonrooted cuttings of `Stevens' cranberry (Vaccinium macrocarpon Ait.) vines were grown in pots to establish the dose response levels for a sand-applied phytotoxin(s) from a crude extract of Pseudomonas syringae (strain 3366) culture. At 114 ppm [milligrams phytotoxin(s)/kilograms sand], the material was noninhibitory, whereas 1140 ppm reduced root and shoot growth significantly in all four species. In subsequent experiments, a 10-ppm dose controlled corn spurry (Spergula arvensis L.) and fireweed (Epilobium angustifolium L.) seedlings, while 103 ppm reduced root or shoot growth of cuttings of the perennial weeds birdsfoot trefoil (Lotus corniculatus L.) and silverleaf (Potentilla pacifica Howell). Root and shoot growth of partially rooted `McFarlin' cranberry vines was reduced at 103 and 563 ppm, respectively. The phytotoxin(s) could potentially control germinating annual weeds in newly established `Stevens' cranberry bogs.

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Carolyn DeMoranville, Brian Howes, David White, and Daniel Shumaker

Although cranberry production typically requires a low fertilization rate compared to many crops, bog waters are generally discharged through surface water flow directly to streams, ponds or lakes and indirectly to coastal waters. Since discharge is primarily to fresh water bodies, and since such waters are generally phosphorus-limited, P is the fertilizer element of most environmental concern in Massachusetts cranberry production. This study was designed to determine how much P enters and leaves cranberry bog systems on an annual basis, what activities contribute to nutrient releases, and what management changes can reduce P discharges. On a total budget basis, including fertilizer applications as inputs and crop and other biomass (leaves) removal as outputs, the bogs were generally net importers of total N and total P. However, total P in outgoing waters was greater than that in source water. Net TP fluvial output averaged 2.08 kg·ha–1·yr–1 in 2002 (range 0.01 to 4.15); 1.66 kg·ha–1·yr–1 in 2003 (range –0.63 to 3.62) and 1.22 kg·ha–1·yr–1 in 2004 (range –1.24 to 4.30). The primary path of nutrient discharge from the bogs was through surface water. Flooding events were the primary source of total P output from the cranberry bogs. Gross total P export from the cranberry bogs was within the range of that for other reported agricultural land uses but greater than that for forested lands. When fertilizer P input was reduced (20% to 35%) at cranberry bog sites for two consecutive seasons, crop yield was not adversely affected and P discharge was reduced compared to that in the initial (prereduction) year.

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Carolyn J. De Moranville*

Cranberry fruit development was studied in 3 years at the Univ. of Massachusetts Cranberry Station farm. Beginning at 4 weeks from 50% out of bloom and continuing until late Sept, 5 replicate samples of 25 fruiting uprights were collected biweekly from each of 7 cultivar beds. Fruit were removed from uprights and sorted into size classes using stacked soil sieves (16-, 12.5-, 9.5-, and 5.6-mm grids). Fruit from each class was counted and weighed. `Ben Lear', a native Wisconsin selection and the fourth most planted cultivar in Massachusetts, consistently produced the greatest yield (mass) of fruit. This was attributed to consistent fruit retention and large fruit size (majority of fruit at harvest were >12.5 mm in dia). In comparison, `Pilgrim', a large-fruited hybrid cultivar, was near the median for fruit yield due to poor fruit set (≈1.2 berries per upright compared to ≈1.6 for `Ben Lear'). `Stevens', the hybrid cultivar of choice in the MA cranberry industry, had yield similar to `Ben Lear' in only 2 of 3 years. Fruit set and retention in `Stevens' was less than that in `Ben Lear', but larger mass of individual fruit in `Stevens' generally made up for fewer fruit produced. Native cultivars `Early Black' and `Howes', which account for >50% of the MA cranberry acreage, had variable yield attributable to variable fruit set and retention by year. These cultivars bear small fruit (≈1 gm/berry; only half of berries >12.5 mm in diameter). Growth curves showed evidence of a `lag phase' in cranberry fruit mass accumulation occurring approximately at the mid-point of fruit development. Although much of the final fruit mass had accumulated by Sept, additional mass did accumulate up to the harvest of the beds (≈1Oct.). This has implications for growers who harvest fruit in early Sept for `white' cranberry juice.

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Rodney Serres and Brent McCown

The gene encoding β-glucuronidase, GUS, has been inserted into cranberry and is expressed in various tissues. Detectable expression of the GUS gene is enhanced up to 15x when the phenol-adsorbing compound, polyvinylpolypyrrolidone, is included in the extraction buffer of the fluorometric MUG assay, indicating that an endogenous, probably phenolic, compound is inactivating the foreign enzyme. Extracts from in vitro-grown cranberry leaves reduce the activity of purified β-glucuronidase in fluorometric assays. This is in contrast to extracts from other plants which have no affect on the enzyme. Detectable expression of the GUS gene for an individual transclone varies with the age of the tissue and the environment in which the plant is grown. The BT gene, which encodes for the Bacillus thuringiensis δ-endotoxin, was also inserted into cranberry with the purpose of incorporating lepidopteran insect resistance. Bioassays using an important insect pest on cranberry show generally inconsistent feeding patterns on transgenic plants. These results may be due to the interaction of the endogenous compounds and the B.t. δ-endotoxin.

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Teryl R. Roper and J. Klueh

The sources of carbohydrate and other resources for fruit growth in cranberry (Vaccinium macrocarpon Ait.) can be spatially partitioned into new growth, old leaves, and woody stems or other adjoining uprights. This research was conducted to determine which spatial source of resources was most important for fruit set in cranberry. At fruit set in late June, we removed the current season growth, one year old and older leaves, or both from 50 uprights per treatment plus a control at two locations. At harvest, fruit set, fruit number and size were determined. In all cases, removing the current season's growth significantly decreased fruit set. Removing both the current season's growth and old leaves produced an additional reduction in fruit set. Removing only old leaves reduced fruit set at one location but not the other. Fruit length, diameter or mean berry weight was not reduced by any treatment. The response of cranberry to resource limitation apparently is to reduce fruit numbers rather than fruit size. This research suggests that current season growth is the primary source of carbohydrates for fruit set in cranberry and that once the fruit are set they have sufficient sink strength to attract resources from a distance.

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Chad E. Finn, Carl J. Rosen, and James J. Luby

Root sections of cranberry (Vaccinium macrocarpon Ait. cv. Searles) were microscopically examined to document the typical anatomy of cranberry roots and changes in root anatomy in response to N-form and solution pH. Cranberry cuttings were rooted, then established in hydroponic conditions with three N and two pH regimes. The three N regimes with equal N levels were 1) NH4-N alone, 2) NH4/NO3-N in combination, or 3) NO3-N alone. pH was maintained at 4.5 or 6.5. Root apical regions were examined using phase contrast, bright field, and epifluorescence microscopy. The cranberry root tip develops with a closed apical organization with the tetrarchal vascular cylinder, cortex, and root cap traceable to independent meristem cell layers. The most obvious treatment difference was an accumulation of unidentified “granules” in the subepidermal layer, readily visible with epifluorescence microscopy with NO3-N alone. Roots produced at pH 4.5 branched less than those at 6.5 and had more “quiescent” root initials; at pH 6.5, these developed more frequently into branch roots.

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James J. Polashock and Nicholi Vorsa

DNA fingerprinting has been useful for genotypic classification of American cranberry (Vaccinium macrocarpon Ait.). Polymerase chain reaction (PCR) based methodologies including randomly amplified polymorphic DNA (RAPD) markers are relatively easy to use, and inexpensive as compared to other methods. However, RAPD markers have some limitations including seamless interlaboratory transferability and susceptibility to certain types of error. An alternative method, sequence characterized amplified regions (SCARs), was developed for cranberry germplasm analysis. Nine primer sets were designed from RAPD-identified polymorphic markers for use in two multiplex PCR reactions. These primer sets generated 38 markers across a cranberry germplasm collection. Estimates of genetic relatedness deduced from employment of the RAPD and SCAR methods were compared among 27 randomly chosen cranberry germplasm accessions. Although both methods produced comparable results above 0.90 coefficient of similarity, branches below this level exhibited variation in clustering. SCAR and RAPD markers can be employed for identifying closely related genotypes. However, the inferences of more distant genetic relationships are less certain. SCAR marker reactions provided more polymorphic markers on a per reaction basis than RAPD marker reactions and as such more readily separated closely related progeny. When SCAR primers were fluorescent dye-labeled for computerized detection and data collection, reduced marker intensity relative to unlabeled reactions was one problem encountered.

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Justine E. Vanden Heuvel and Joan R. Davenport

Information on growth and carbon partitioning of cranberry uprights in response to soil N application is lacking. Therefore, two experiments were initiated on `Stevens' uprights to determine the effect of soil-applied N on tissue N, growth, net carbon exchange (NCER), and nonstructural carbohydrate production of uprights of `Stevens' cranberry. Tissue N concentration increased linearly with increasing soil N but was greater in vegetative uprights than in fruiting uprights. Current season growth on vegetative uprights was more responsive to tissue N than on fruiting uprights. Although chlorophyll concentration and NCER increased with increased soil N, upright starch concentration and often total nonstructural carbohydrate concentration decreased with increased soil N at midfruit development and preharvest, especially in vegetative uprights.

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Hilary A. Sandler and Carolyn J. DeMoranville

Field conditions associated with commercial cranberry (Vaccinium macrocarpon Ait.) production were simulated in greenhouse studies to determine the effect of soil surface characteristics on dichlobenil activity. Sand was compared with organic matter, in the form of leaf litter, as the surface layer. A seedling bioassay using alfalfa (Medicago sativa L.), a dichlobenil-sensitive plant, was employed to determine root growth response on herbicide-treated soil. When the herbicide was applied to a sand surface, root growth was greater as time after application elapsed, indicating loss of herbicide activity. Conversely, the presence of organic matter on the surface prolonged the activity of the herbicide. Composition of the surface layer was more important than the depth of the layer in determining herbicide persistence. The influence of cultural practices, such as the application of sand or the removal of surface debris, on herbicide activity should be considered when planning weed management strategies for cranberry production. Chemical name used: 2,6-dichlorobenzonitrile (dichlobenil).

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Carol D. Robacker and S.K. Braman

Azalea lace bug (Stephanitis pyrioides) is the most serious pest on azalea. Both evergreen and deciduous azaleas are susceptible, though more resistance has been observed in the deciduous. To identify genes for resistance, fourteen deciduous azalea species, three deciduous azalea cultivars derived from complex hybrids, and one evergreen cultivar were planted in a randomized complete-block design under mixed deciduous trees in the fall of 1994. Each block was replicated 12 times. In the spring and summer of 1995, azalea lace bugs were introduced onto branches of six plants of each of the taxa. One month later, and again in the fall of 1996, the percentage of infected shoots per plant was measured. Very little damage from azalea lace bug was observed on the R. canescens, R. periclymenoides, and R. prunifolium plants, while `Buttercup', `My Mary', R. japonicum, and R. oblongifolium had the greatest damage. The cranberry rootworm, Rhadopterus picipes, damages many woody ornamentals, including some azalea species. The injury appears as elongated cuts on the leaves, and is most severe on plants growing under dense canopies. The cranberry rootworm has been observed in this azalea field plot. Plants were evaluated for damage in June 1995 and 1996. Cranberry rootworm damage was most severe on `Buttercup', R. japonicum, R. prinophyllum, and R. calendulaceum, while the evergreen azalea `Delaware Valley White' was the most resistant.