Characterization of Cranberry Decline in British Columbia Cranberry Beds RESEARCH REPORT, December 2015

Transcription

1 Charaterization of Cranberry Deline in British Columbia Cranberry Beds RESEARCH REPORT, Deember 201 Projet Coordinator: Dr. Rebea Harbut, KPU CO-PIs: Dr. Peter Oudemons, Rutgers University Dr. Les Lavkulih, Land and Food Systems, University of British Columbia Collaborators: Brian Mauza, Oean Spray Canada Julie, Wilson, Land and Food Systems, UBC Cranberry Growers Researh Assistant: Taku Somaya Summary The overall aim of this projet is to haraterize ranberry field deline aross the region and identify ontributing fators in order to develop a strategy and tools that will allow growers to identify beds that are at risk, develop best management praties to prevent the ourrene of CFD and to provide reommendations for fields that have symptoms of CFD. Previous researh suggest no pathogens or insets are involved as the primary ause. However, it does appear that altered soil harateristis resulting from an inreased rate of peat degradation as well as redued oxygen ontent are more losely orrelated with this syndrome. The data that has been olleted over the past field season has provided valuable information about the soil environment that is related to the ourrene of ranberry field deline. Over the past field season, the researh team has ompleted a omprehensive survey of the study sites whih inluded a survey of peat depth, plant growth analysis and detailed soil analysis, historial prodution praties survey and limate survey at the study sites. Defining BC Cranberry Prodution Systems: BC ranberry beds have several unique harateristis that are not shared with other growing regions. Two major fators that ontribute to this differene are the peat based beds, ompared to sand based systems in other regions and the thikness of the anopy. As most of the researh arried out on ranberries has been onduted in sand based systems, many of the standard definitions and haraterization of prodution systems are not appliable in BC. The establishment of terminology and methodologies to haraterize BC s ranberry prodution systems is ritial to developing baseline data to begin to systematially develop a researh-based understanding of BC ranberry beds in order to ensure new tehnologies and prodution praties are utilized appropriately to enhane the sustainability of the BC ranberry industry. In this projet, the haraterization of anopies and soils and the use of satellite imagery as a diagnosti tool to identify areas that are affeted by CFD is providing valuable data to develop management praties related to CFD and also to develop a deeper understanding of BC s unique prodution system. 1

2 Objetive 1: Examine, map and desribe the distribution and spread of ranberry field deline over the past years in BC ranberry beds 1. Examine, map and desribe the distribution and spread of ranberry field deline over the past years 1.1. Assemble a olletion of satellite and aerial imagery for affeted ranberry prodution areas in Rihmond and Pitt Meadows areas for the past years Map areas within ranberry beds affeted with ranberry field deline using urrent and histori aerial and satellite imagery to determine the rate and pattern of spread Using a GIS approah, ollet soils maps and hydrologi data as well as land use/land over layers to evaluate landsape level patterns in the development of ranberry field deline. 1.. Identify affeted beds to be used for ground based investigations. In addition, identify at least non-affeted beds that an be used as healthy omparisons In the site seletion proess, there were farms that were identified as ideal for site investigations. These six sites represented a range in severity of CFD symptoms and also represented different aged beds. During the site seletion proess, it was determined that due to the high degree of variability aross all the sites, the non-symptomati omparisons would be taken from the same farm in the viinity of the field in order to allow the identifiation of key variables that differ between symptomati and non-symptomati areas. Therefore, at eah site, there were more samples olleted and analyzed from three defined areas; 1) CFD affeted areas 2) transitional areas (adjaent to the CFD affeted areas) and 3) non-symptomati areas. This approah has allowed for the understanding of the physiologial plant harateristis and the soil harateristis that are assoiated with the appearane of CFD. Image analysis was arried out using the exhibit A imagery provided by oean spray. The image analysis indiated that many of the ourrenes of CFD appear to be related to irrigation and drainage while other fields appeared to develop in a more random pattern. This relationship between soil moisture and CFD is supported by the soil analysis data that is presented below. The ourrene of CFD does not appear to be related to geography as there are fields where one has extreme CFD symptoms while adjaent field shows no indiation of symptoms. Analysis of the study sites using NDVI indiates that there is great potential to use this type of imagery as a diagnosti tool to determine the development of CFD prior to the symptoms being obvious in the field. With the inreased aessibility of aerial imagery, there is great potential to utilize this this imagery as a diagnosti tool for early detetion of CFD. Future work would be foused on orrelating the diagnosti data olleted in the field on a wide range of beds to NDVI imagery. 2

3 Fig.1 NDVI imagery of ranberry beds in Rihmond, BC. Dark blue indiates high vegetation with dereasing vegetation with lighter olour. Objetive 2: Detailed haraterization of ranberry beds to evaluate orrelations between ranberry deline symptoms and soil and plant harateristis 2.1. Develop a bioassay to evaluate the rooting apaity of affeted vines and soil 2.2 Assemble detailed soil data to establish the rate of soil deomposition and baseline oxygen/redox potential for soils with and without ranberry field deline. 2.3 Determination of soil profile harateristis by ground penetrating radar and ore analysis. 2. Colletion of plant growth data to evaluate orrelation between plant harateristis and ranberry deline 2. Colletion of historial and urrent rop management reords and weather data for the intensive sampling sites. During the field season, muh of the researh arried out was foused on haraterizing the soil and plants in ranberry beds with and without CFD symptoms to identify the fators ontributing to the deline. The soil and plant work will allow for the development of best management praties to prevent, manage and treat CFD. 3

4 2.1. Develop a bioassay to evaluate the rooting apaity of affeted vines and soil This objetive was intended to identify if there are hemial omponents in the soil that may be preventing the rooting of ranberry plants in the soil. As a preliminary test, samples of the rooting medium in a severely affeted area were taken with as little disturbane as possible and plaed in plasti bags, and in a plug tray. Cuttings of plants from an unaffeted plant in the same bed were stuk in the trays to determine if rooting ourred. Rooted ranberry plugs were planted into this rooting medium and seeds of ranberries taken from the same bog were dropped on the soil medium in sealed plasti bags. From the same site a 3 inh ore was taken to a depth of 20 entimeters. Into eah of the top profiles we plaed two ranberry uttings to root. Cranberry uttings rooted in the soil profiles and in the soil from the affeted area in the plug trays did not appear to be inhibited as rooted developed in a normal time frame. In the sealed bags the ranberry seeds germinated and grew to one leaf stage before the bags were opened. Plugs ontinued to grow out and appeared with no signs of stress. There appeared to be little effet of the soil on germination of ranberry seeds or the growth of the seedlings. The results of these tests suggested that from these in vitro trials there may not be immediate effets from the soil like toxi gases or omponents. It was determined that although the ores were taken arefully, the disturbane was suffiient to hange the rooting environment whih may have ontributed to the development of CFD. As a result it was deided to pursue other areas of the ranberry field deline projet. Soil Profile Charaterization aross study beds One of the most unique aspets of BCs ranberry prodution system is that ranberries are grown on peat soils. Peat is a hallenging medium to grow rops as peat requires saturated onditions in order to maintain its struture and prevent deomposition whereas ranberries required well drained soils. Methods In order to develop an understanding of the onditions of the peat, one meter soil ores were olleted aross eah of the study sites to determine the depth of the peat and the degree of dehumifiation at eah site. The soil ores that were sampled at eah site were taken from the entire field and therefore inlude areas that were showing symptoms of CFD and other areas that were not. Dehumifiaiton is measured using a method alled the VanPost sale, whih is a squeeze test ommonly used to quantify the state of deomposition of a soil. This was arried out for eah of the soil ores (Appendix D). The sale ranges from 1 (raw, undeomposed peat) to (highly deomposed peat). For eah site, a map was generated that illustrates the depth of peat and a data table (Appendix E) was generated defining the degradation of the peat at varying depths of the soil. The data was analyzed to develop histograms that depit the frequeny of a ertain Van Post rating.

5 Results The 1 meter soil ores provided an overview of the depth to the underlying lay layer and also provided information about the soil horizons throughout the site. Most of the sites had varying depth to the lay layer aross the beds. It does not appear that the depth to the lay layer is a onsistent fator in developing CFD as the fields were highly variable. However, a shallow soil layer may inrease the risk of developing the soil onditions that ontribute to CFD due to poor drainage through the soil profile and it is likely an important fator. Fig 2. Example of soil ore map for site. Eah bar represents one 1m ore olleted at the site. Yellow bar indiates peat and grey portion of the bar represents lay. 2.2 & 2.3 Assemble detailed soil data to establish the rate of soil deomposition and baseline oxygen/redox potential for soils with and without ranberry field deline. Determination of soil profile harateristis by ground penetrating radar and ore analysis. L.M. (Les) Lavkulih and J.E. (Julie) Wilson INTRODUCTION Cranberry fields in the Lower Mainland of British Columbia are experiening field deline. Some ranberry fields that were healthy have developed a network of pathes where the vines no longer produe a rop and eventually die off (Figure 3). Preliminary results suggest that the soil in the deline areas does not have a root environment that provides the appropriate balane between available water and oxygen for effetive root respiration. It has been found that the soil substrate and the rooting zone is heterogeneous and variable, whih is believed to result in inadequate rates of air

6 exhange in the rooting zone. The origin of organi soils (peat) are known to be horizontally layered through a vertial rosssetion. Individual layers of varied origin of organi matter and degree of deomposition aumulated as the peat bog developed. The thikness of the peat is not uniform but varies as affeted by the underlying mineral terrain on whih the organi material has aumulated. In the Delta area of BC, peat deposits are found mainly as aumulations of organi materials over floodplain deposits (alluvium), and an have a thikness from a few entimeters to over a meter. The horizontal layering is the result of the variable growth onditions from open water to fen to bog over the past,000 years. The original fen materials, derived from sedges and rushes, are more readily deomposed than the bog plant remains derived from mosses, willows and a few oniferous speies. The hypothesis is that this, in addition to management praties of leveling, drainage, and fertilization, has resulted in a heterogeneous rooting zone for the ranberry vines. For healthy root growth, atmospheri air enrihed with oxygen must diffuse from above the soil surfae into the rooting zone; in addition, the arbon dioxide from root respiration within the rooting zone must diffuse to the atmosphere. As the diffusion of air is diretly related to soil porosity, adjaent thin layers of differing porosity retard the uniform rate of air diffusion (see Appendix A). If the rooting zone environment beomes defiient in oxygen it will beome anaerobi. This an be assessed by measuring the oxidation-redution, or redox, status of the soil. Preliminary results of two fields sampled in 201 provided evidene that there is greater humifiation, or presene of lay layers, with lower porosity and lower redox potential in the deline soil areas in omparison to the adjaent nonsymptomati areas (Table 1). Typial soil redox potential ranges are presented in Appendix B. Table 1.Preliminary soil data olleted from Affeted (A) and Non-Symptomati (NS) pathes at Site 1 OM=Organi Matter

7 This researh report fouses on the soil aeration/water/nutrient onditions in the ranberry root environment between deline ( Affeted ) areas and adjaent Non-Symptomati areas. Figure 3. Cranberry field exhibiting pathes of deline (dark grey) in Rihmond, BC. METHODS Six () sites (fields) exhibiting the range of severity of ranberry field deline were seleted in ollaboration with researh partners. At eah site, a transet of approximately metres long was laid out, interseting both an Affeted (A) area and an adjaent Non-Symptomati (NS) area, resulting in two plots per field (Figure ). Around eah transet, soil ores were taken to a depth of one metre (the photographs in Appendix C show only the top 0 m) to reord the stratigraphi layers underlying the A versus NS areas. The stratigraphi ore analysis provided an assessment of the number and thikness of layers within the soil olumn, as eah layer has a unique porosity and hene a gaseous diffusion rate. Samples were olleted from all depths examined. Photographs were taken of the ores in the field and the morphologially different layers were identified, Samples were taken to the UBC Soil-Water- Environment Lab (SWEL) and analyzed for ph and estimation of organi matter ontent by the method of Loss on Ignition (LOI). Samples from two sites were examined for a preliminary assessment of redox (Eh) and degree of humifiation In addition, an exploratory assessment of field eletrial ondutivity

8 was done with a remotely operated above-ground mobile unit that traversed a total distane of about 0 metres. The transet inluded a deline area and the adjaent NS region. Figure. Example of field transet and soil ore sample loations. Eah site ontains 3 samples from affeted areas (1 sample diretly on transet), and samples from non-symptomati areas.

9 RESULTS Soil Organi Matter Perent organi matter was measured in eah distint layer of the soil profile down to 0 m for eah sample (all data presented in Appendix C). Results presented here fous on the soil depths diretly assoiated with ranberry rooting zone (0-1 m), and the layers immediately below this (1-30 m). Perent organi matter values presented here represent a weighted average for these two soil depths (Table 2, Figures & ). The results show learly the variability among the six sites inluding by depth and thikness of visibly different layers of the soil material. Although not onlusive deline sites tended to ontain lower amounts of organi matter than adjaent NS sites and there appears to be a slight inrease in organi matter with depth in the NS sites. The opposite seems to our in the deline sites. Appendix C provides more omparative data. Table 2. Weighted average perent organi matter on both affeted and non-symptomati samples, at 0-1 m and 1-30 m depth.

10 Figure. Weighted average % OM ontent, 0-1 m. Affeted samples in red (n=3), non-symptomati (NS) samples in blue (n=). Boxplots presented only for NS samples. Whiskers represent minimum/maximum values. Figure. Weighted average % OM ontent in the 1-30 m depth. Affeted samples in red (n=3), non-symptomati samples in blue (n=).

11 Soil ph Soil ph was measured in both water and CaCl2. Figure shows a strong orrelation between ph in water and ph in CaCl2 and the rest of our results are reported for ph in water (Table 3, Figures, &). Not surprisingly there is a strong relationship between ph measured by the two methods. The major differene noted is that the affeted deline sites have a greater range of ph and tend to be greater than the NS sites. The NS sites values are lustered between ph 3 and. (CaCl2) in the NS sites. This suggests that the soil onditions are less variable in the NS sites when ompared to the A (deline) values. Figure. ph measured in water versus ph measured in CaCl2 for all samples olleted on affeted and nonsymptomati sites. Table 3. Weighted average ph in water on both affeted and non-symptomati samples, at 0-1 m and 1-30 m depth 11

12 Figure. Weighted average ph measured in water, 0-1 m. Affeted samples in red (n=3), non-symptomati samples in blue (n=). Boxplots presented only for NS samples. Whiskers represent minimum/maximum values. Figure. Weighted average ph measured in water, 1-30 m. Affeted samples in red (n=3), non-symptomati samples in blue (n=). Boxplots presented only for NS samples. Whiskers represent minimum/maximum values.. 12

13 Soil Organi Matter and ph Relationship Anomalous soil harateristis were investigated by first identifying outliers in a orrelation of soil ph and soil OM at both 0-1 m depth (Figure ), and 1-30 m depth (Figure 12). Figure. Comparison of the weighted average ph and % organi matter of affeted and non-symptomati (NS) samples, 0-1 m. At the 0-1 m depth, there were four samples with unusually high ph values (_ ). In general, the high ph was observed to be assoiated with high degrees of deomposition or presene of mineral material (e.g., Site ). It also appears that this field has been sanded. Mineral horizons in the rooting zone orrelate with higher ph values. In addition, there were three samples with low soil OM (<%), two of whih were found in Site 3. Here, a distint sand layer was observed, ontributing to the redued % OM (Figure 11). The third sample with low OM was olleted at site, but upon visual verifiation of the soil ore photo, this alulation appears to be a laboratory error: the OM ontent is expeted to be muh higher based on the dark blakish-brown soil olor from 0-20 m depth. 13

14 Figure 11. Example of a soil ore sampled at Site 3, NS plot, with a learly visible sand layer in the ranberry rooting zone from 3- m. 1

15 Figure 12. Comparison of the weighted average ph and % organi matter of affeted and non-symptomati (NS) samples, 1-30 m. At the 1-30 m depth, one sample from Site had very low % OM (<2%), due to the presene of a thik lay layer extending from ~13 m deep to the bottom of the profile (>0 m) (Figure 13). 1

16 Figure 13. Example of a soil ore sampled at Site, NS plot, with a distint, extensive lay layer from 13 m to >0 m depth. 1

17 Number of Soil Layers The average number of visibly distint soil layers in the 0-30 m depth was generally higher in Affeted samples than in Non-Symptomati samples (in all sites exept Site 2) (Table ). Although the total number of visibly distint layers do not differ between the two sites there is a suggestion that the number of layers in the upper 30 m of the rooting zone are greater in the A (deline) sites. This observation needs to be quantified by more detailed sampling and measurements of redox onditions within eah distintive layer. This will be one of the major tasks during the next field studies to be onduted in January 201. Table. The average number of soil layers (distinguishable by observed olor differenes) found in the top 30 m of affeted and non-symptomati soil samples at all sites. Eletrial Condutivity Figure 1 provides a preliminary evaluation of utilizing above-ground surfae measurements of eletrial ondutivity as a measure of dissolved ions or hemials, in soil solution in the upper portion of the rooting zone of a ranberry bed. Blue and green olors indiate low levels of dissolved ions, or and orrelate with NS pathes, while yellow and red are illustrative of inreased ion onentrations, and orrelate with Affeted pathes. The higher the onentrations of the measured ions, the lower the oxygen ontent. The figure illustrates the heterogeneity of the surfae of the ranberry field over a distane of approximately 0 m. The high degree of agreement between the preliminary ondutivity measurements and the observed pathes of ranberry field deline indiate the potential utility of this tool to measure the suseptibility of fields that ould be transitioning into an affeted state (symptoms of deline). 1

18 Figure 1. Example of a heat map of eletrial ondutivity (red = high, blue = low) values. High values are orrelated with observed ranberry field deline affeted areas (dashed lines). SUMMARY The results onfirm the hypothesis that the observed deline areas within the ranberry beds have soil harateristis that restrit the exhange of air between the ranberry rooting zone and the atmosphere. Root respiration and mirobial ativity within the rooting zone produe arbon dioxide and other gases suh as hydrogen sulfide, whih result in a defiieny of oxygen required for healthy root growth. The defiieny of oxygen ontributes to anaerobi onditions within the rooting zone. This may be assessed by measuring the redox potential (an indiator or the presene of oxygen). The major onern that requires remediation is to enhane the exhange of air from the root zone and the atmosphere. The fields are inherently variable as a result of the history of the bog prior to the establishment of ranberry beds. The original layering of the organi materials of different degrees of deomposition (humifiation), and variable thiknesses to the underlying mineral subsoil, modified by leveling and bed preparation has exaerbated the heterogeneity of the soil medium, espeially the ative rooting zone (0-1 m). Soil ore samples and the eletrial ondutivity survey onfirm this heterogeneity. Soil ph tends to be higher in affeted areas, as well as the number of ontrasting layers. Soil ph indiated anaerobi onditions and inreased humifiation and ontrasting layers of different degrees of humifiation, or organi layers interspersed with mineral (lay) layers restrits air (and water) movement within the ative rooting zone. Future investigations to be onduted prior to the next field season inlude a detailed examination of the transets within the six fields to assess field measurements of redox potential and degree of humifiation between Non-Symptomati and adjaent Affeted areas. 1

19 2. Colletion of plant growth data to evaluate orrelation between plant harateristis and ranberry deline The symptoms of CFD inlude weak plant growth, brittle vines, abnormal root growth and development, low root:shoot ratio, and in severe ases, death of the vines. Plant growth data was olleted in both non-symptomati areas, transition areas and CFD affeted areas to determine the harateristis that exist as the bed moves towards showing CFD symptoms. This analysis was arried out on the same sites as the detailed soil data olletion. When the researh team began the field work to haraterize the growth parameters, it beame quikly apparent that the methodologies typially used in ranberry growth analysis were not appropriate for BC ranberry beds. Therefore, new methodologies and terminology was developed to desribe the beds. Canopy Charaterization Methods The anopy struture of BC ranberry beds is unique ompared with any other growing region due to both the depth and omposition of the anopy. In most regions, the anopy is limited to the depth of the uprights and a minor amount of older runner growth beneath. The ranberry beds that were inluded in the study appear to be fairly typial for the growing region with anopies that are 20-30m in depth. In order to desribe the anopy, it was neessary to divide the anopy into two distint setions, the green anopy and the brown anopy depth. This separation is neessary due to the different physiologial funtion of the two omponents of the anopy. Green Canopy (Fig.1A) this is the photosynthetially ative omponent of the anopy that represents the portion of the anopy that ontributes to aumulating new arbohydrates through photosynthesis. The effetiveness of the green anopy is partially dependent on the overall health of the plant as well as the mirolimate in the anopy partiularly in regards to light, temperature and humidity as all these fators diretly influene photosynthesis. Brown Canopy (Fig. 1B) this portion of the anopy is omposed of non-photosynthetially ative material and does not ontribute to the assimilation of arbon, but plays an important role in the storage of arbon in the plant. This woody tissue an provide a soure of arbohydrate for plants during early spring growth, and an provide a soure of arbohydrates if either photosynthesis or root funtion is ompromised. Runner length although the researh team had planned to ollet data on runner length and number, the arhiteture of the anopy and the length of the runners made this a very diffiult variable to quantify. 1

20 Results There are two key observations related to the measurements of anopy depth. The first is that the depth of the green anopy remains relatively onstant between the areas that were nonsymptomati and the transition areas but then shows a signifiant drop (Fig.1A). The seond key observation was that although the green anopy depth did not hange muh between the transitional and non-symptomati areas, the brown anopy showed a onstant derease in depth as you moved from non-symptomati to affeted areas (Fig.1B). The dereased depth in the brown anopy is likely aused by an inrease in dead wood whih beomes brittle and ompresses with the weight of mahinery that moves over the bed (ie. sprayer, beaters). As previously mentioned, the brown anopy an funtion as a arbohydrate reserve. If the plant is unable to meet arbohydrates (due to redued rooting apaity or other stress) the plant will utilize arbohydrates stored in the brown anopy. If the plant ontinues to use reserve arbohydrates faster than it is able to replenish them the tissue will die. This relationship between the anopy health and arbohydrate reserve is an important fator in the development of CFD. m A: Green Canopy A T N A T N A T N A T N A T N A T N m B: Brown Canopy A T N A T N A T N A T N A T N A T N site 1 site 2 site 3 site site site site 1 site 2 site 3 site site site Fig.1: Green anopy depth (A) and Brown Canopy Depth (B) reorded in areas with a range of CFD symptoms (A: affeted, T: transition, N: non-symptomati) at eah study field (site 1 to ). Blak error bars indiate standard error (variability) around eah mean value. The resoure alloation of arbohydrates from the brown to the green anopy is further supported by the data olleted on upright density (Fig. 1). Square foot ounts were arried out at all six sites and in of the sites, there was no derease in upright density until the anopy was severely affeted by CFD when upright density dropped dramatially. This is again onsistent with the tendeny 20

21 for plants to alloate resoures to plant omponents that are atively growing and therefore have the highest need for arbohydrates. 00 Total Upright Number A T N A T N A T N A T N A T N A T N site 1 site 2 site 3 site site site Fig.1: Mean total upright ount per ft 2 for eah ondition (A: affeted, T: transition, N: non-symptomati) at eah study field (site 1 to ). Error bars indiate standard error (variation) around the mean. Whole Plant Growth Analysis Methods Prior to harvest a destrutive plant analysis was arried out to quantify growth on a fresh weight and dry weight basis. 3 ore samples were olleted from eah area (non-symptomati, transitional and affeted), washed and separated into roots, brown anopy and green anopy and weighed for fresh weight (Fig. 1). Plant material was then plaed in a drier at 0 0 C and dried until onstant weight. Yield data was olleted at eah site using a square foot quadrat. Three separate square foot measurements were olleted in eah of the areas (affeted, transitional and non-symptomati) at eah site. Results Consistent with the anopy depth data, plant biomass was signifiantly redued in the affeted areas ompared to the transitional and symptom free area. There was no signifiant deline in the green anopy between the transitional and symptom free area, but there was a signifiant derease in the amount of brown anopy. As the brown anopy is a major soure of stored arbohydrate, the maintenane of the green anopy may have been failitated by the stored arbohydrate in the brown anopy. As the reserves in the brown anopy are depleted, the tissue dies and beomes more brittle resulting in redued depth and mass. This may provide some evidene as to the hypothesis that the anopy is likely under stress for a signifiant period of time before showing symptoms and the symptoms suddenly appear when the reserves in the plant have been depleted ausing the anopy to ollapse. 21

22 A B C D Figure 1. Plant material from the anopy growth (above soil material) from a non-symptomati site (B), transitional site (C) and the affeted site (D). Weight [g] A: Shoot Dry Weight A T N A T N A T N A T N A T N A T N site 1 site 2 site 3 site site site Weight [g] B: Root Dry Weight A T N A T N A T N A T N A T N A T N site 1 site 2 site 3 site site site Figure 1. Dry weight of (a) shoot and (b) root for eah ondition (A: affeted, T: transition, N: non-symptomati) at eah study field. Error bars indiate standard error around the mean. 22

23 Yield data from the same plots showed signifiantly redued yields in areas that were highly affeted by CFD, however in the transition areas, only one site (site 3) had redued yields in the transition area with 3 sites showing higher yields in the transition areas (Fig.1). This inrease in yield is onsistent with the upright ounts olleted earlier in the season. When plants are under extreme stress they will respond by alloating resoures to reprodutive growth. The data was onsistent with the flowering upright and total flower number olleted earlier in the season as well Weight [g/sq.ft.] A T N A T N A T N A T N A T N A T N site 1 site 2 site 3 site site site Fig. 1. Total yield per ft 2 for eah ondition at eah study field. Error bars indiate standard error around the mean. Conlusion The anopy of ranberries growing in BC are unique due to the existene of the brown anopy whih an at as a storage reserve but also an reate a physial barrier to the soil surfae whih may ontribute to the poor rooting density of the anopies. The ability for the brown anopy to provide a reserve allows the plantings to ontinue produing rops even under onditions where the rooting apaity is not suffiient to meet rop demands. As a result, the appearane of CFD symptoms are not seen until the planting has been under signifiant stress for a long period of time. The symptoms assoiated with CFD do not our until the planting has reahed a point where the reserves in the anopy are depleted and the plant unable to meet the rop needs due to the ompromised root system and redued rooting apaity. 2. Colletion of historial and urrent rop management reords and weather data for the intensive sampling sites. The historial and urrent management reords were olleted for the all study sites that are inluded in the intensive sampling sites. Weather data is also being olleted from the losest weather 23

24 station available for eah site. Management data requested inludes nutrient, water and pest management, yield, sand appliations, renovations, et. Weather data will inlude preipitation, temperature, light and where available, soil moisture. Data will be used to inform the interpretation of soil and plant data olleted and with the image analysis. A survey with eah of the growers for the six deline study sites were arried out through the fall of 201. Survey areas of onern are shown in Appendix A. We asked for the history of the beds in question, and for the last years the fertilizers applied and any upgrades to irrigation and drainage systems. We reviewed the last years of pestiide use reports filed with Oean Spray of Canada, Ltd. and grouped pest management into groups for omparison. The survey information was derived from in person interviews and exhanges of information when all the information was not available. We targeted those farm praties and infrastruture that may ontribute to ranberry field deline. The age of beds with deline ranged from years with no apparent onnetion to the appearane of the problem. Previous rops or vegetation ould only suggest that some of the deline sites ould be linked to hanges in the soil struture espeially when learing the land with trees. Examining imagery of the sites prior to learing the vegetation may be worth pursuing. It is interesting that in most ases the deline symptoms were first noted in the past years. Fertilizer rates are between 0-0 pounds of nitrogen per are for of the sites. Combined with the release of nitrogen from the peat and deposition from the atmosphere these may be ontributory fators. In most ases the bed yields did not warrant this level of nitrogen. A few of the sites had tissue analysis available and growers did not see any levels of nutrients that would warrant onern. Most of the solid set irrigation systems were similar in design, but operation during frost protetion irrigation and harvest did differ and was onstantly hanging on any one site. Soures of irrigation water were the north arm of the Fraser River for of the sites and one site was supplied water from the main arm of the Fraser River via the No. Road intake. Water ontamination was possible but no other foliar symptoms appeared exept at Site where we think high eletrial ondutivity aused some desiation during 201 and 201. Sub-surfae drain frequeny aross the fields did vary onsiderably, mostly due to the time of planting as a result of the urrent thinking of that partiular year. Some growers have sanded these fields but most have not. Spot treatments were prevalent mostly as a means to ounter the ranberry deline. Pestiide use was looked at initially and again in this survey. Appliations of herbiides were of partiular interest. Appliations of a pre-emergent herbiide, dihlobenil (Casoron), were in the middle of the reommended amounts and most of the produt was applied in very early spring. Its herbiidal effet is known to last only about weeks. Test from the previous year s study showed levels of 1 ppm in August after an appliation of 0 pounds per are. Assuming a rooting depth of. m. this would represent an appliation amount of 1. ppm dihlobenil. Mesotrione (Callisto) appliations are known to have pre-emergene effets on young seeds and seedlings. All of the sites only used spot treatments to ontrol weeds. Many of these sites may have been in deline areas. In 201 no mesotrione residues were found in the soil on severe deline sites. No further doumentation is available from eah site. 2

25 Table. Summary data from the grower survey from the sites evaluated. SITE AGE OF PLANTING CASORON NITROGEN DRAINAGE SPACING Sides only Soil moisture data was olleted at three of the sites, however due to malfuntioning soil moisture probes, the data were not reliable for analysis. Weather data was olleted from Environment Canada s weather station at YVR for the past 1 years ( ). The data was used to alulate growing degree days, and key weather variables were olleted that are most likely to impat plant growth; winter highs, summer lows, GDD and preipitation. Light measurements were not available. Over the period of time that we have seen ranberry field deline develop, there have not been any major weather events that an be determined to have had a signifiant impat on the deline. Temperature [] A Temperature (oc) B Mean Temperature Year Summer High Winter Low Figure 20. Summer high and winter low temperatures for (A) and average monthly temperatures (B) Soure: Environment Canada Growing degree days is an important variable that has a signifiant impat on the development of the rop (Fig.21). The umulative GDD has not showed any onstant trends over the past 1 years with some of the seasons with the highest GDD being from 200, 200 and 201. However, it is important to note that the average winter temperatures in the region are well above freezing and therefore it is likely that there is metaboli ativity that ontinues to our in the plants. This is 2

26 important beause as opposed to other regions, it means that the plants are not photosynthesizing but ontinue to require energy to maintain the low level of metaboli ativity throughout the winter Growing Degree Days /1 2/1 3/1 /1 /1 /1 /1 /1 /1 /1 11/1 12/1 Time [day] Figure 21. Cumulative Growing Degree Days (Base 0 C, Max 30 0 C). Soure: Environment Canada Objetive 3. Condut field trials to evaluate management tehniques on beds affeted by CFD This objetive was intended to be arried out on a large field that had severe CFD symptoms where different management strategies ould be arried out and evaluated for impat. However, there were two fators that resulted in the deision to eliminate objetive 3 from the projet. In order to address the worsening CFD symptoms, the grower deided to arry out substantial sanding on the bed. As this resulted in a non-uniform field, it would be diffiult to arry our ontrolled experiments where only one management pratie was evaluated. The seond fator was that the researh team felt that there was not suffiient understanding of the onditions ontributing to the CFD to strategially selet management praties that should be evaluated. Based on the results of the studies arried out in 201, the researh team has disussed different management options that may address the soil onditions that have been identified as ontributors to CFD. 2

27 Conlusions The results of the 201 data olleting have provided a baseline of information about the ranberry anopy and the soil onditions that are assoiated with CFD. There are a few key onlusions that an be drawn: - There is great potential to use NDVI imagery as an early detetion tool for identifying fields at high risk for developing CFI. - The development of the anopy in many ases is resulting in a thik brown anopy whih ats as a arbohydrate reserve, but also provides a physial barrier to new growth oming into ontat with the soil whih would prevent rooting. - The redued apaity for new growth to establish roots puts inreased need for the development of a strong root system during planting establishment and to maintain the health of the root system. - The results of the soil analysis indiate that the onditions in the rooting zone are not optimal for healthy root growth due to poor aeration. - The poor onditions in the soil ompromise the root system and result in inreased dependene on the arbohydrates reserve in the brown anopy. - Soil parameters suh as ph and redox, humifiation and layering are potential indiators of risk for developing CFD - Plant harateristis suh as depth of brown and green anopy, rooting density are important indiators or risk for the development of CFD. Future Work: - Evaluation of diagnosti tools as indiators for risk of CFD on ranberry beds throughout the region. - Determine management praties that optimize the soil onditions to promote and maintain healthy root growth. - Identify management praties that enourage the establishment of a strong root system during the establishment of a new plantings. - Identify management praties that would optimize the anopy arhiteture to allow for suffiient arbohydrate reserve while failitating root establishment. ACKNOWLEDGEMENTS The researh team would like to thank the BCCMC and Oean Spray for supporting this projet and the growers that have served on the advisory ommittee for this projet. Funding for this projet has been provided by Oean Spray Cooperative and by Agriulture and Agri- Food Canada and the BC Ministry of Agriulture through the Canada-BC Agri-Innovation Program under Growing Forward 2, a federal-provinial-territorial initiative. The program is delivered by the Investment Agriulture Foundation of BC. 2

28 Appendix A. Charateristis of soil pore size and their influene of gaseous movement. 2

29 APPENDIX B. Typial soil redox potential (Eh) value ranges. < +30 beomes limiting for most plants As Eh dereases, bateria are more adapted than fungi. APPENDIX C. Soil sample ores (to 0 m depth) and assoiated layer thikness, loss on ignition values (%) and ph (water, CaCl2). Number of soil ores = (3 x Affeted and x Non- Symptomati for eah of sites). Sample labeling sheme: S = Site number, A = Affeted (deline) sample, NS = Non- Symptomati Sample Attahed as a separate PDF file. 2

30 APPENDIX D. Example of soil ore photographs taken at eah site. Images shown are from site and represent ore #C1, #C2 and # C. Core images allow for detailed doumentation of the transition from peat to lay and also provides information regarding horizon development. 30

31 s s s APPENDIX E. Vanpost data for all study sites. Eah olumn represents one soil ore with depth intervals from 0-0 m. Brown olour indiation vanpost rating (1, undeomposed peat, highly deomposed peat) with darker brown indiating higher rates of deomposition. Dark blue olour indiates a mixture of peat and lay, green indiates large piees of plant material present in the ore, light blue indiates sand layer, grey indiates lay. Legend: Van Post Sale Color hart H: m Clay & oragani mix (mostly lay, not tested) p Plant material (thik roots, piee of wood, et) s Sand &organi mix (mostly sand, not tested) Clay (not tested) Humifiation index - Van Post Sale [Least deomposed:h1<-->h:most deomposed] Site Site Site 3 Site 2 Site Site Site 3 C1 C2 C3 C C C C C C C1 C2 C3 C C C C C C C1 C2 C3 C C C C C C C C11 C12 C13 C1 C2 C3 C C C C C C C1 C2 C3 C C C C C C TC1 TC2 TC3 C1 C2 C3 C C C C C C C C11 C12 C13 C1 C1 C1 C1 Site 2 Site Site T Site 1 Site 1 p 2? p s s Bed_names ore_no. Site Site T Soil_depth [m] m m m ? p p m m s s p m 3 m m 3 3 m