4.1.1   Pruning Methods for Wild Blueberries at the NSWBI Field Station.
Collaborator: Andrew King, NSDAM

The objective of this study is to compare growth and production of blueberries pruned by three methods over a number of production cycles.

There were no differences among the three pruning treatments (oil burn, straw burn, mow) over six production cycles (no yield data for the 1994 -1995 cycle), nor were there consistent differences among the treatments for total stem length, buds per stem or blossoms per stem. These results suggest that the type of pruning has no influence on growth and production of the wild blueberry when fertilizers are not applied. The expected completion of this project is yet to be determined.

4.1.2   Pollinating Wild Blueberries Profitably.
Collaborators: Dawn Wickstrom, NSAC; Diane Dunlop, NSAC; John Tait, NSAC

The objective of this study is to determine an economical "break even" point for stocking wild blueberry fields, based on production data over four years.

Production data from all of the pollination study fields from the past four years was obtained from the producers, and that from 152 fields was fed into the analysis program and tested to determine the level of hive numbers per acre (stocking rate) that would provide maximum return to the producer. That number for the 152 fields over the four years was 1.25 hives per acre. Future analysis will address more fields, the economic level in individual years, and the level in fields with data over several production cycles.

4.1.3    Effects of Mulches on Spread of Blueberries.
Collaborators: Dr. P. Hicklenton, AAFC; Andrew King, NSDAM.

The objective of this study is to assess the effectiveness of several types of mulches to encourage blueberry rhizome growth and spread.

Very little spread has been noted since the mulches were applied in the fall of 1997. A second application of mulches is planned for 2000.

4.1.4    Effects of Gypsum and Fertilizer on Wild Blueberries.
Collaborators: Kevin Sanderson (project leader), AAFC

The objective of this study is to assess the effects of gypsum and fertilizer, singly and in combination, on growth and development of the wild blueberry.

Applications of gypsum + fertilizer resulted in longer stems than in control plots, but had no effect on buds, blossoms and fruit yield over the first production cycle. Leaf tissue levels of sulphur remained high in plants from plots amended with gypsum in 1998. Soil levels of nutrients varied among the five sites included in the study. Completion date for this project is 2002.

4.1.5    Two Versus Three-Year Management of Wild Blueberries.
Collaborators: Andrew King, NSDAM; Doug Wyllie, Bragg Lumber Company

The objectives of this project are as follows: 1) to compare the effects of two-year management (1 crop) and three-year management (2 crops) on blueberry development and yield; 2) to compare fertilization and non fertilization on both management types; 3) to compare burning and mowing.

This 12-year study will be completed in 2000. At that time, we will be able to compare the two-year and three year management practices, as well as mowing versus burning and fertilizer versus no fertilizer, over two production cycles.

4.1.6   Rates of Phosphorus on Wild Blueberries.
Collaborators: Kevin Sanderson, AAFC; Dr. G.W. Stratton, NSAC; Dr. P.R. Warman, NSAC; Ryan Ring, NSAC

The objectives of this study are as follows: 1) to assess the effects of increasing levels of phosphorus fertilizer on blueberry growth and production; 2) to determine the fate and effects

Levels of phosphorus in both leaf tissue and soils increased with increased level of phosphorus fertilizer applied (0 to 92 kg P2O5 ha-1 ) during the 8 seasons of the study. There were no differences in stem length, buds, blossoms or yields among the treatments. Level of phosphorus in plots amended with high rates of P remain high. Ryan Ring is testing several soil extractants to determine the one best suited for wild blueberry soils. Residual effects of the different rates will be followed over the next several cycles. The expected completion date for this project is 2005.

4.1.7   Site Specific Management of Wild Blueberry Fields.
Collaborators: Dr. K. MacKenzie, AAFC; Dr. P. Hicklenton, AAFC; Dr. K. Jensen, AAFC; Dr. N. Nickerson, AAFC; Dr. P. Hildebrand, AAFC; Rick Delbridge, NSDAM; Gary Patterson, AAFC; Dr. Rob Gordon, NSDAM; Carl Esau, NSDAM; Lorne Crozier, NSDAM; Dale McIsaac, NSDAM; Andrew King, NSDAM; Gary Brown, Bragg Lumber Company.

The long term goal of this study is to develop sustainable management strategies for wild blueberry production; short term goals include: 1) to measure and assess variability within commercial fields with respect to field characteristics, plant growth and production; 2) to develop optimum site specific management practices related to factors that influence production; 3) to develop variable rate technologies to apply rate specific management practices to fields.

Soil and tissue samples have been obtained from seven commercial fields, including two (Adams and Esau) that are part of an M.Sc. study by William Malay. Grids were set out at each field and soil and tissue samples were taken at each grid point that had blueberries. Data obtained varied considerably within and among the fields assessed. Several years and many fields will likely be required for us to determine the most appropriate methods for assessing site variability.

4.1.8    Effects of Moss on Wild Blueberries.
Collaborators: Dr. P. Hicklenton, AAFC; Dr. K. Jensen, AAFC; Gary Patterson, AAFC; Andrew King, NSDAM; Dale McIsaac, NSDAM; Dr. D. Percival, NSAC; Glen Sampson, NSAC; Katriona MacNeil, NSAC; Gary Brown, Bragg Lumber Company.

The objectives of this study are as follows: 1) to assess the extent and influence of mossy patches in fields on numbers of blueberry stems, stem length, buds, etc.; 2) to develop methods for moss control in commercial fields.

Preliminary investigations in 1999 showed that several commercial blueberry fields had varying amounts of moss (primarily Polytrichum spp.), with North Nova (Earltown) having nearly 30% cover. At the North Nova field, blueberry plants were severely restricted in moss patches (100% moss cover) compared to areas without moss. These data suggest that full moss cover will reduce potential blueberry yields over time. During 2000, we plan to expand the research to include the biology and life cycle of the moss, soil pH and nutrient levels, extent of moss problems in the industry, and explore some possible controls.

4.1.9   Mowing Efficiency in Wild Blueberry Fields.
Collaborators: Doug Wyllie, Bragg Lumber Company

The objectives of this study are as follows: 1) to determine if mowing at different heights alters plant growth and production; 2) to determine the most economical plant height at which to mow; 3) to compare spring and fall mowing.

Initial stem lengths after mowing at both sites (spring at Adams and fall at Murray Siding) varied with the height of mowing, but there were no differences in plant height by July at either site. At the Adams field, buds per stem and fresh fruit yields did not differ from each other. Production data will be gathered from the Murray Siding field in 2000. The data to date suggest that mowing height does not affect fruit production in wild blueberries. The expected project completion date is 2000.

4.2   Research Project: Ryan Ring

4.2.1   A Comparison of Five Extraction Methods for Determining Available Soil Phosphorus in Nova Scotia Blueberry Soils.
Collaborators: Dr. P. R. Warman (co-supervisor), NSAC; Dr. G. W. Strattor (co-supervisor), NSAC, Dr. L. J. Eaton, NSAC

The objective of this project is to determine the best predictor of plant available phosphorus, for the lowbush blueberry, from the following methods: Mehlich 1, Mehlich 3, Bray 1, Modified Morgan and the Anion Exchange Membrane (AEM). This project was initiated in 1999 with three newly established sites and two sites in long term experiments, conducted by Dr. L.J. Eaton. One of these long term sites is located at the Nova Scotia Wild Blueberry Institute, and was set-up to study the phosphorus requirements of the lowbush blueberry. In 1999, soil samples were taken in April (spring), and at harvest in August (late summer) from the NSWBI. Along with the soil samples obtained at harvest, tissue samples were obtained to allow for correlation of the soil phosphorus to the phosphorus present in the tissue. These samplings will be repeated in the summer of 2000, with the late summer samples obtained at tip dieback. Thus far, various background soil characteristics have been measured; and the Mehlich 1, Mehlich 3 and Bray 1 extractions of the spring and late summer soil samples have been completed. However, no statistical analysis of this data has been completed. The anticipated completion date of this project is April 2001.

4.3   Research Project: Dr. David Percival

4.3.1   Influence of Nitrogen Formulation and Application Date on the Plant Nutrition, Growth and Development, and Yield of Wild Blueberries.
Collaborators: NSWBI; WPBANS; and Bragg Lumber Company.

A study examining the influence of nitrogen formulation and application date was initiated at the Nova Scotia Wild Blueberry Institute and at a commercial field at Westbrook N.S. Nitrogen applications consisted of applying 25 kg·ha-1 N on 15 October 1997, and 15 May 1998 with the nitrogen source consisting of ammonium nitrate, ammonium sulphate, or urea. No deleterious effects of autumn nitrogen applications on winter hardiness were observed in this study. No significant differences in stem length, floral bud number, fruit zone length, and node number were present between autumn and spring fertilized treatments. A significant effect of nitrogen source was present, with the ammonium sulphate treatments having longer stems, a greater number of floral buds, greater node number, greater berry number, and greater harvestable yield than the control. Therefore, results from this preliminary experiment indicate that yield potential of lowbush blueberries can be influenced by nitrogen formulation. However, before recommendations are made, more replication is required, and the main and interactive effects of nitrogen, phosphorous, and potassium fertilizers needs to be examined.

4.4   Research Project: Angela Dryden

4.4.1   Impact of simulated acid rain on photochemistry, morphology, and yield components of the lowbush blueberry (Vaccinium angustifolium Ait.).
Collaborators: Dr. D. Percival (supervisor), NSAC; NSWBI; and Glen Sampson, NSAC.

As of 1998, anthropogenic sources are estimated at releasing 100 to 130 million tons per year of sulfur dioxide emissions and 60 to 70 million tons per year of nitrous oxide emissions (Nebel and Wright, 1998). Acid rain is a problem that affects plants, animals, and insects, thus it is important we know as much as possible about it. Both the indirect (i.e. photochemistry) and direct (i.e. leaf lesions) effects of simulated acid rain are of importance to perennial crops such as the lowbush blueberry (Vaccinium angustifolium Ait.). Since lowbush blueberries are a two-year crop, the cumulative effects of acid rain can be increased because the plant has to sustain injury for two years instead of one.

The objectives of the following investigation were to: find a threshold at which acid rain will cause damage to the blueberry plant, determine the impact on photochemistry, characterize the morphological damage to the vegetative and reproductive components, and lastly determine the effect on crop yield.

The field experiment was carried out at the Nova Scotia Wild Blueberry Institute in Debert, NS on wild lowbush blueberries in their cropping year of production. A latin square experimental design was used with five replications, five treatments, a plot size of 5 by 5 m, and a buffer between plots of 2 m. The treatments used consisted of simulated sulfuric acid rain (diluted H2SO4) at pH's of 5.6 (control), 4.0, 3.0, 2.0, and 1.5. After eight application dates fluorescence and net photosynthesis measurements were taken. Enough plant and berry samples were taken to determine the effects of acid rain on yield components and yield.

Although there is a significant decrease (8%) in the fluorescence origin, there was no significant difference between maximal fluorescence, quantum efficiency of PSII photochemistry, net photosynthesis, or wax deposition in either leaf or berry. No significant effects of net photosynthesis could be due to the lowbush blueberries being hypostomatous (stomata are on the bottom of the leaf). The acid rain solution was not being absorbed through the stomata and affecting the photochemistry. It can be observed that both berry and leaf wax deposition increased as pH lowered. The epicuticular wax layer may help negate the effects of the acid rain treatments.

Of the yield components, stem length treatments were not significantly different from each other. Significant effects of acid rain treatments on total node number, berry weight, and berry number were present with pH 1.5 treatment having 6% fewer nodes, 30% greater berry weight, and 35% higher berry number than the control. There was no observed significant difference between the treatments of quadrat yield.

Overall, there were no direct effects to the lowbush blueberry (fluorescence, net photosynthesis, epicuticular wax, yield components and yield) by the simulated acid rain treatments. If there is any negating effect present it may take numerous growth cycles for it to become apparent in components that were measured. There may also be a beneficial aspect, as the elemental sulfur in the acid rain provides a micro nutrient that is deficient in blueberry soils. However, this study was only conducted for one season, there may be a cumulative effect over a number of seasons.

4.5   Research Project: Bonna Jordan

4.5.1   Impact of Living Mulches on the Environment and Growth Dynamics of the Lowbush Blueberry (Vaccinium angustifolium Ait.).
Collaborators: Dr. D. Percival (supervisor), NSAC; Gary Patterson, AAFC; Gordon Brewster, NSAC; NSWBI; WBPANS; and Bragg Lumber Company.

There has been an increase in the use of herbicides such as hexazinone (Velpar) which destroy weeds and produces bare spots. With no vegetative cover these bare spots are susceptible to soil erosion and their microclimate conditions (e.g. temperature and drought stress) are not very favorable for blueberry growth. During mechanical harvesting the blueberry rhizomes are ripped and destroyed which also reduces the coverage of blueberries and produces bare spots susceptible to erosion. Soil erosion has become a major problem in Nova Scotia's wild blueberry fields. It has been proposed that this problem can be minimized by using living mulches (companion crops) to improve soil stability and microclimate conditions and therefore reduce erosion in blueberry fields which will in turn cause an expansion in blueberry coverage and increase the yield and profit.

The objective of this study is to determine the effects of living mulches on the physical and chemical environment and growth dynamics of the lowbush blueberry. This is being determined by examining; 1) The physical environmental conditions which will be monitored by measuring the temperature, moisture and pH of the soil, 2) Changes in soil stability and hydraulic conductivity and 3) Changes in the growth dynamics, biomass productivity and establishment of the lowbush blueberry and living mulch. Studies examining the use of introduced living mulches are being conducted at two commercial fields in 1999 and 2000 near Upper Stewiacke and Rawdon, Nova Scotia. A randomized block experimental design will be used with the treatments consisting of (1) a control (no living mulch), (2) a creeping red fescue, hard fescue, and perennial ryegrass mixture, and (3) a birdsfoot trefoil, tall fescue, and perennial ryegrass mixture.

Results show no detrimental interactions occurring between the living mulch and lowbush blueberry and an improvement in soil physical conditions (i.e. hydraulic conductivity). With these improvements the blueberries have an increased potential of spreading into these once bare areas resulting in a decrease of soil erosion and an expansion in blueberry coverage.

4.6   Research Project: Cheryl Konoff

4.6.1   Seasonal Changes in Nutrient Dynamics of Wild Blueberry Production.
Collaborators: Dr. D. Percival (supervisor), NSAC; NSWBI; WBPANS; and Bragg Lumber Company.

With the exception of carbon and oxygen, which are supplied via the atmosphere, plants acquire nutrient elements from the soil. Nutrients are an essential requirement for plant growth and development with 16 inorganic nutrients being required to ensure the normal growth and development of a plant. The demand for a nutrient is dependent upon its function within a plant and its relative mobility. The nutrient concentration within a particular tissue can vary over the span of a growing season, and is dependent upon the assimilation and allocation patterns, and also the potential remobilization of specified nutrients. More specifically the rhizomes of the lowbush blueberry constitute a large proportion of the biomass of a wild blueberry and are thought to be a large storage or source organ for nutrients (Smagula and DeGomez, 1987). However, the relative strength of the rhizome as a source for nutrients is uncertain and insufficient information is available on the seasonal nutrient dynamics of the lowbush blueberry.

Consequently, the objectives of this investigation were to examine the nutrient dynamics of the lowbush blueberry in the sprout and cropping phases of production over the span of a growing season.

This study was conducted throughout the 1997 and 1998 growing seasons at the Nova Scotia Wild Blueberry Institute. A completely randomized experimental design was used with four replications in the sprout and cropping fields. Three whole plant samples were collected on six different days beginning in May and ending in September. Leaf, root, and rhizome samples were collected, dried, ashed and analyzed for nutrient content using the methodology of (Perrin, 1999). The concentration (%) of phosphorus, calcium, magnesium, and potassium and the concentration (ppm) of boron were examined.

This study provides preliminary insight into the inorganic source/sink dynamics of the lowbush blueberry. With the exception of phosphorus levels of leaf tissue in the sprout year, leaf tissue concentrations were higher than the roots and rhizomes. As the blueberry leaves matured, evidence of a reduction in phosphorus and potassium and accumulation of calcium and magnesium were present. Such results are typical of a growing plant (Jones, 1998), and indicate the differences in assimilation and allocation that occur amongst nutrients.

All nutrients except phosphorus are within the optimal ranges required for growth of the leaves as described by Smagula and DeGomez (1987). Boron levels in the leaf tissue were not sufficient at the start of the season, but did increase throughout the season. However, when processes such as pollen tube growth and berry development were occurring, boron deficiencies may have been encountered. In addition, no evidence of remobilization of nutrients from the rhizotomous tissue to the leaves and roots was present with nutrient level not changing significantly over the span of the growing season. Therefore, results from this study cast doubt on the importance of the rhizotomous tissue as a nutrient reservoir. However, only two seasons of data have been used in this study, and more replication is required before pertinent conclusions can be made.

4.7   Research Project: Lindsay Hainstock

4.7.1    Getting Back to Basics: Carbon Assimilation and Allocation in Wild Blueberry Plants.
Collaborators: Dr. D. Percival (supervisor), NSAC; J. P. Prive, AAFC; Dr. N. Crowe, NSAC; NSWBI; WBPANS; and Bragg Lumber Company.

There are three general avenues used to increase the production of any crop; improved genetics, decreased competition of pests or disease and improved management practices. Up until now, research has focused on increasing production by the introduction of fertilizers, pesticides, and new production techniques (Eaton, 1994). Choices were based on trial and error approaches, without attempting to understand how the plant grows. The basic physiology of most important agronomic crops has already been determined and used to aid producers. An understanding about the fundamental physiology of a crop is important for making optimum management decisions that will maximize results without wasting time and resources. (Hall et al. 1971; Fernandez and Pritts, 1994). This includes an understanding of the efficiency of the plant to utilize light energy, assimilate and metabolize carbon, nutrient dynamics, and source/sink relationships. The objectives of this experiment were to measure the assimilation rate of carbon and how it is allocated throughout the lowbush blueberry plant for both the sprout and crop growing season.

CARBON ASSIMILATION: Photosynthetic and fluorescence readings will be taken weekly throughout the growing season for both the crop and sprout stages of production. A LI-COR portable photosynthesis measurement system (LI-6200; LI-COR Inc.) was used for measuring net photosynthetic rate. The leaves will be removed and the leaf area determined using a LI-Cor leaf area meter (LI-3100, LI-COR, Lincoln, Nebraska). The pigments will be extracted using 80% acetone and the concentration will be measured using a spectrophotometer.

CARBON ALLOCATION: Whole plant samples were taken for a given area. The plant material within the area will be separated into roots, rhizomes, shoots, and berries. Dry weights will be determined for each section. The number of vegetative and reproductive nodes as well as stem length will also be determined for each area. The dried samples will then be ground for use in determining the non-structural carbohydrates. Carbohydrate analysis will be determined using HPLC with an NH4+ based column. The carbohydrates that will be measured are glucose, sucrose, fructose, and starch. Starch content will be analyzed by being broken down into glucose units and run through the HPLC.

It would be very beneficial to increase the efficiency of research by first understanding the normal growth of the lowbush blueberry. By understanding the way a plant distributes energy and growth, decisions can be made that utilizes the natural cycle of the plant and maximizes yields with minimal inputs. This applies to such things as timing of fertilizer application. Knowing when the plant is most actively growing and will benefit the most from an applied fertilizer, would reduce the amount of fertilizer being wasted through leaching and erosion as occurs with excessive applications. Understanding the physiology of the plant is also beneficial in determining indicators that can be used to predict plant yield in the fields (Angus et al.1993) or for choosing high production cultivars (Forsyth and Hall, 1965).

4.8   Research Project: Peter Burgess

4.8.1    Efficacy and Crop Phytotoxicity of Several Herbicides on Commercial Wild Blueberries Vaccinium angustifolium Ait. and Introduced Living Mulches.
Collaborators: Dr. Glen Sampson (co-supervisor), NSAC; Dr. D. Percival (co-supervisor), NSAC; Andrew King, NSWBI; and Sara Reid, NSWBI.

This study involved two distinct phases. A herbicide screening study was done at the Nova Scotia Wild Blueberry Institute, from which herbicides that showed low phytotoxic effects could be tried on a second phase, an introduced living mulch greenhouse trial at the NSAC. This trial looked at the herbicide effectiveness on the introduced living mulches and also looked at herbicide tolerance.

The NSWBI portion of the study involved a section of relatively homogenous, semi-commercial wild blueberry field, used to test the phytotoxic effects of 11 treatments on the blueberry plants. Treatments of a standard, (hexazinone, applied to entire treatment area earlier in spring after burning), imazethapyr, nicosulfuron/rimsulfuron, thifensulfuron-methyl, chlorimuron, Flumetsulam/metolachlor, fluazifop-p-butyl, prosulfuron, rimsulfuron-elim, quizalofop-ethyl and clethodim were applied, on top of the hexazinone application before full emergence. Phytotoxic characteristics were rated for each plot on a 0-9 scale ( 0 = nil affect, 9 = plant death ). Ratings were done at one, four, and eight weeks after application.

The greenhouse study was set up as a completely randomized design and involved five different living mulch species (Creeping Red Fescue, Hard Fescue, Sheep Fescue, Perennial Rye Grass, and Birdsfoot Trefoil). Fluazifop-p-butyl, prosulfuron, nicosulfuron/rimsulfuron (Ultim), tribenuron-methyl, hexazinone, and a control (no herbicide application) were applied on each of the five living mulches and replicated five times. The living mulches were then rated for phytotoxic effects at one, two, and four weeks after the herbicide applications. It was determined which living mulches have the best tolerance against full herbicide applications which showed low phytotoxic effects on lowbush blueberries.

In the field trial at the Nova Scotia Wild Blueberry Institute Chlorimuron, imazethapyr and flumetsulam/metolachlor produced mean phytotoxic effects greater than (2.75). This high rate was deemed to be unacceptable for further study at full rate. Fluazifop-p-butyl (Fusillade), prosulfuron (Peak), and nicosulfuron/rimsulfuron (Ultim) showed mean phytotoxicity ratings lower than (2.75) and had desirable action spectrums.

The broad spectrum herbicides nicosulfuron/rimsulfuron and hexazinone, showed a very high phytotoxic activity when applied to the introduced living mulches in the greenhouse. However, there was some tolerance with creeping red fescue and sheep fescue when fluazifop-p-butyl and tribenuron-methyl were applied. Further study into varying rates of different herbicides should be done to develop an integrated vegetation management plan.

4.9   Research Project: Vimy Glass

4.9.1    Effect of Soil Moisture on the Growth and Development of the Lowbush Blueberry (Vaccinium angustifolium Ait.) - A Field Study.
Collaborators: Dr. D. Percival (supervisor), NSAC; John Proctor, U of Guelph; J. P. Prive, AAFC; and Dr. R. Olson, NSAC; NSWBI; WBPANS; and Bragg Lumber Company.

As we enter the twenty-first century, the lowbush blueberry (Vaccinium angustifolium Ait.) is becoming highly valued for its health benefits especially its antioxidant properties. Greater consumer usage will demand an increase in production efficiency. Consequently, research interests are focusing upon increased potential and actual yield through a better understanding of the growth, development, and optimal management practices for the crop. Moisture is necessary for flower bud development and for increasing blueberry weight (Benoit et al., 1984). Indigenous blueberries maximize their weight and volume three to four weeks prior to harvest. Therefore, rain or irrigation applied at the start of this period would be most effective for increasing fruit size (Hall and Forsyth, 1967).

The objectives of the field study were to examine the effect of soil moisture availability (supplemental irrigation, moisture stressed) on i) leaf gas exchange, and ii) vegetative and reproductive growth of the lowbush blueberry (Vaccinium angustifolium Ait.). This study was conducted during the 1998/ 1999 growing seasons at the Nova Scotia Wild Blueberry Institute (NSWBI) in Debert (45^o 26' N, 63^th 27' W), Nova Scotia.

Two soil moisture conditions were used as treatments (irrigated, moisture stressed) as well as a rainfed control and were arranged in a randomized block design. Plot sizes measured 304.8 cm (10 ft) by 304.8 cm (10 ft) with 60.96 cm (2 ft) buffers between. Water was restricted on moisture stressed plots through the use of portable rainout shelters (Clawson et al., 1986). Transparent acrylic sheets measuring 66.04 cm (26 in) by 243.84 cm (96 in) were used as covers and securely attached corner to corner ensuring little movement from the wind. During the growing season, the shelters were placed over the moisture stressed plots only where there was a >50% chance of rain. A weekly supplemental irrigation schedule was followed. Applications of 20 mm of water were be supplied to each plot. Rain gauges were positioned throughout the irrigation plots to ensure a uniform, correct application. Parameters measured included photosynthesis, chlorophyll and carotenoid content, stomatal conductance and stomatal density, stem water potential, yield components (stem length, node and floral node numbers, flowering zone length, number of flowers, berry number and sample yields), and soil moisture. At this time, statistical analysis is being completed and conclusions can not be provided.

4.9.2    Influence of Decreasing Soil Moisture on Stem Water Potential, Transpiration Rate, and NCER of the Lowbush Blueberry (Vaccinium angustifolium Ait.) - A Controlled Environment Study.
Collaborators: Dr. D. Percival (supervisor), NSAC; John Proctor, U of Guelph; J. P. Prive, AAFC; and Dr. R. Olson, NSAC; NSWBI; WBPANS; and Bragg Lumber Company.

Increased consumer demand has prompted an urgency in a greater understanding of environmental conditions on the growth and development of the lowbush blueberry (Vaccinium angustifolium Ait.). Breeding efforts are limited due to the fact that the fruit are marketed as an indigenous crop. Therefore, increased demand can be met by improving production efficiency through a greater understanding of the physiology of the crop. As such the objectives of this study attempted to determine the direct short term effects of decreasing water availability on stem water potential, transpiration rate and NCER in the lowbush blueberry.

Wild blueberries (Vaccinium angustifolium Ait.) were placed in computer regulated growth chambers in the Dept. of Plant Agriculture, at the University of Guelph, Guelph, ON. The effects of moisture stress were measured using a randomized complete block design were results were blocked by chamber and there were two levels of moisture availability as the experimental factor, moisture stressed and control. The growth chambers monitored net carbon exchange rate (NCER). Additionally stem water potential was recorded using in situ temperature corrected psychrometers (P.W.S. Instruments, Inc., Guelph, Ont.) and transpiration rates were measured gravimetrically. Soil moisture was monitored using Theta probes (Delta-T Devices Ltd, Cambridge, UK).

The study lasted approximately 120 hours spanning four complete illumination cycles. Preliminary statistical analysis of the full model provided averages of each of the three parameters of interest. Further analysis with multiple regression provided parameter estimates. Diurnal patterns were observed in all parameters of interest. Significant treatment effects between stem water potentials were found in the third and fourth illumination cycles. However, due to fluctuations in readings, no linear or quadratic equations could be fitted to the data. Transpiration rates began at the same levels (i.e., same intercept, linear and quadratic slopes). The linear and quadratic slope estimates remained consistent between the drought and control while the intercepts in the moisture stressed plants decreased. The photosynthetic estimates for the first illumination cycle was the same in both the control and drought plants, 3.17 µmol·m^-2·s^-1. Over the course of the study, the drought plants displayed higher intercepts estimates yet lower slope estimates leading to a decrease in photosynthetic rates. During low water availability, the substantial decrease in stem water potential coupled with the conservative photosynthetic and transpiration rates indicate the lowbush blueberry is a drought tolerant plant in the short-term. Physiological adaptations in response to environmental variability during the reproductive cycle of the indigenous blueberry will be further examined in the filed portion of this study.

4.10   Research Project: Gloria Pickett

4.10.1    Controlling Black Bulrush by Spot Spraying with Ultim at the Nova Scotia Wild Blueberry Institute.
Collaborator: Andrew King, NSDAM.

The objective of this experiment was to observe the level of control of Black Bulrush by spot spray with Ultim (nicosulfuron/ rimsulfuron). The project was set up as a randomized complete block design. Plot size measured 1m by 1m, with a 0.5 m buffer zone between replications. There were two Ultim application times, the first in June 1999, and the second in September, 1999. The four treatments tested are as follows: (1)Control; (2) 67g/800L H₂O (June 22, 1999); (3) 67g/800L H₂O (September, 1999); (4) 100g/800L H₂O (June 22, 1999); and (5) 100g/ 800L H₂O (September 1999). Each treatment was replicated four times. Crop tolerance and weed control was rated using the 0-9 Rating Scale used by the Expert Committee on Weeds. The results of the June application of Ultim showed moderate injury, noticed by bronzing of the leaves. Overall, the June applications did not give 100% control, but did suppress the growth and prevented it from going to seed. Treatment 4 was the most successful at controlling the Black Bulrush. It is advisable from this project that fruit bud formation should be looked at closer in the future. This project also looked at lowbush blueberry crop tolerance to spot spray applications of Ultim. This involved treating an area of approximately ˝ m² around the center stake. This involved the same treatments, with three replications. Treatment 2 caused minimal amount of stunting to the plants while treatment 4 caused a greater amount of stunt growth in the plants. The expected project completion for this project is 2000.

4.10.2    Broadcast Application of Ultim to Control Black Bulrush (Demonstration Trial).
Collaborator: Andrew King, NSDAM.

The objective of this demonstration trial was to examine the effects of a broadcast application of Ultim on Black Bulrush present in lowbush blueberries. Plot size measured 2m by 5m. There were two Ultim application times, the first in June 1999, and the second in September 1999. The two treatments tested were as follows: (1) 67g/ 200L of water/ha; and (2) 134 g/200L of water. There were no replications of the treatments. Crop tolerance and weed control were rated using the Expert Committee on Weeds, 0-9 Rating Scale. The results of the June application showed that there was moderate injury, noticed by the bronzing of the leaves. This application also appeared to prevent the Black Bulrush from flowering. The expected project completion for this demonstration was 1999.

4.11   Research Project: Dr. Sonia Gaul

4.11.1    Improved IPM of the Blueberry Fruit Fly.
Collaborators: Lorne Crozier, NSDAM; Dr. K. MacKenzie, AAFC; cooperating blueberry growers.

The interception of the blueberry fruit fly, Rhagoletis mendax Curran, before the female adult lays eggs in the developing fruit is the basis of the insect control strategy for this pest of lowbush blueberries. Studies in 1999 have investigated the influence of trap type and trap spacing on the interception of adults of the blueberry fruit fly in commercial lowbush blueberry fields, including the NSWBI site, and the influence of mulch type on the emergence pattern of the blueberry fruit fly in caged field plots. The Pherocon yellow sticky trap is the more effective trap type of two yellow sticky cards tested. Blueberry fruit flies emerged earlier from sand mulch than from sawdust or bark mulch. Trap spacing trials are ongoing.

5.   FIELD STATION ACTIVITIES