Alternate Bed Renovation System for Cranberry Production

Stolon Length and Soil Amendments Experiment - The first objective of this study was to evaluate bed establishment methods based on stolon segments (stolons cut to specified length) broadcast over an area or bed, and measures that would help maintain stolon contact with the bed surface. The variables evaluated were stolon segment length (SSL) and soil amendments, in a side-by-side comparison with the conventional system, for a total of 14 treatments evaluated. Since a major objective was to develop a system that used less initial vine material, the SSL treatments employed half the amount of vine (0.5 ton per acre) as the conventional treatment (1 ton per acre). This experiment was carried out in 2000 and repeated in 2001. A red/near infrared camera was used to obtain a measure of vegetative cover (NDVI). The possible range in value of NDVI is between minus one and one, but the typical range is between 0.01 (almost no green or bare soil) to 0.6 (for a very green area).

The factor SSL was evaluated at three levels (2.5, 5.0, 7.5 cm) to determine what minimum stolon cutting length would be optimal for survival in a broadcast system. The 7.5 cm (3-inch) SSL treatment resulted in significantly greater vegetative cover (NDVI) than the conventional method, and greater cover than the 2.5 cm (1-inch) SSL treatment, with the cultivar 'Stevens' (Fig. 1). The 7.5 cm (3 inch) SSL yielded the greatest plant density, between 1,200 and 1,500 propagules per meter, for 'Ben Lear' and 'Stevens' (Fig. 2), respectively.

Another factor evaluated were soil amendments, the application of sand or sand/peat mixture at a depth of ⅛ - ¼ inches. The rational for the application of a layer of media on top of the stolons was to determine whether better contact between soil and stolon could be achieved. 'Ben Lear' appeared to significantly respond to topdressing of either sand or sand/peat as determined by NDVI (Fig. 3), and although not significant, topdressing did appear to increase propagule number (Fig 4). The sand treatment significantly increased propagule number with 'Stevens' (Fig. 4). Another factor evaluated was a sand application that was tilled into the soil, no significant effect was observed. A significant cultivar by soil amendment interaction was observed for relative growth rate (Fig. 5). For the cultivar 'Ben Lear', relative growth rate was significantly increased with application of 0.6 cm of sand/peat following broadcast of stolon segments, while it was not significant for 'Stevens'.

The 7.5 cm stolon segments performed as well as or better than the conventional system (Figs. 1 and 2) while the 5 cm stolon segments performed at least as well as the conventional system despite using only half the amount of initial vine material. This in turn accounts for the greater relative growth rate of the 5 cm cuttings (Fig. 5). The bed preparation systems that performed consistently well utilized a sand and peat topcoat (Figs. 3 and 4).

In May 2003, percent cover ratings were made and differences between Stevens and Ben Lear continued to be found. For Stevens, the treatment with the highest % cover (77.5%) was 7.5 cm stolons with topdressing. For Ben Lear, the highest % cover (55%) was the conventional planting system. The plots with 7.5 cm stolon segments, and plots with topdressing generally did better.

Large Scale Bed Establishment Experiment - Experiment two was set up at two locations (including a grower location) in the spring of 2001. In one location, the total area of the experiment was 7200 sq. ft., and the other location was 16,200 sq. ft. The experiments were conducted to determine optimum plant (propagule) density for economically viable bed renovation, identify best management practices for renovating old cranberry beds - nutrient management, and evaluate weed ecology and pressure within alternate plant densities and nutrient regimes consistent with objectives 2-4 in the original proposal. The data from the first experiment originally suggested no large treatment by cultivar interactions; therefore these studies were conducted using the cultivar ‘Ben Lear’ (a cultivar known for its reluctance to establish). This experiment replaced the one originally proposed on the grant through consultation with growers (and Northeast SARE officials). It was decided that growers would be more interested and would require research which would show them that the new methodologies would: 1) be equally effective in a larger scale setting, and 2) that this system can be mechanized for farm-scale application. To bring the experiment to larger scale feasibility, an existing commercially available cutting implement was sought, and a forage chopper was identified as having the potential to accomplish the desired vine cutting operation. Towards that end we borrowed and rented farm machinery to establish large-scale plots. A 'Patz' model 9427 forage chopper (Pound, WI) was rented to cut the cranberry vines into two inch (5 cm) segments, and spreading equipment was borrowed to spread the cut vines, and to apply sand and peat topdressing on the plots. The experimental design was a randomized complete block design (RCBD) with 6 replications, and the cultivar was 'Ben Lear'. The factors evaluated were propagule density and nitrogen, both having 3 levels (Table 1).

The cut vine treatments did not perform as well as the conventional method (Fig. 6). The much lower propagule number in the cut vine treatments was determined to be due to damage to the vines during the cutting process by the 'Patz' forage chopper. This conclusion was reached because when the same vines were cut manually, versus by the Patz machine, a large difference in propagule density was found. It was our determination that the cut vine system was still a viable option to the conventional system, however a new system to cut cranberry vines must be used. Towards that end, it was decided that a custom-built piece of equipment was needed to chop the cranberry vines.

Development and testing of cutter/spreader - An equipment fabricator (Thompson Welding & Fabrication, Pemberton, NJ) was solicited to manufacture a custom machine (designed by grower A. Lee, Lee Bros, Chatsworth, NJ) for cutting cranberry vine and spreading the vine segments in one operation. The cutter/spreader was completed April 2002. The design employs a conveyor vine feed mechanism with a guillotine, and allows for the adjustment of cutting length. A blower blows the cut vine segments out the rear of the machine. The cutter/spreader is stationed on a trailer platform, which is attached to a tractor, and covers about a three-foot swath per pass (see photographs, Fig. 7).

This system was utilized to plant a demonstration trial in a cranberry bed at the Philip E. Marucci Center in May of 2002. The planting consists of four side-by-side plots (24 ft x 81 ft., 1944 sq. ft.), comparing four treatments: 1) conventional system planted with Ben Lear at 1 ton/acre, 2) cut vines of Ben Lear at 1 ton/acre, 3) cut vines of Ben Lear at 0.5 ton/acre, and 4) cut vines of Ben Lear at 1.5 ton/acre. The cut vine treatments included a top dressing of a ⅛ -¼ inch sand/peat mixture with a 'golf-course' top-dressing applicator (Figure 8). In order to prevent the short stolon segments from drying out, the trial was irrigated for a few minutes each hour during the daytime for the first eight weeks, at which point irrigation frequency was gradually reduced. During the summer of 2002, the cranberry stolons rooted and began growth but it was difficult to detect any differences between the treatments. Severe weed pressure was a problem in the bed and may have hindered cranberry plant growth.

In October 2003, the amount of plant cover in each of the four treatments was estimated by counting the number of growing points in 16 4”rings, along two transects of the plots. Little difference was found between treatments, with cut vines at the 1-ton rate having the highest number of growing points (116/sq. ft.), followed by cut vine at 0.5 ton, the conventional system, and then cut vine at 1.5 ton (112, 86, 70 growing points/sq. ft., respectively). Observations in the spring of 2004 again found little difference between treatments.

Growth regulator field experiment – An additional small plot field experiment was planted to again compare the conventional planting method with cut vine propagules (CVP), and to determine whether growth regulators could hasten and increase rooting and growth efficiency in the cut vine system. This research was lead by Dr. Brent Black (USDA, ARS, Beltsville) and was carried out at the Philip E. Marucci Center. The objectives of the experiment were to: 1) compare the establishment of cut-vine propagules (2 inch cuttings) with conventional uncut vines, 2) compare three planting densities of cut-vine propagules (0.5, 1.0, 1.5 ton/acre), 3) determine the effect of pre-plant auxin treatment on propagule survival, and 4) determine the effect of cytokinin on lateral branching.

The bed was planted on June 10, 2002 with ‘Ben Lear’ vines in 3x3 ft. plots. The uncut vines were pressed in, and the cut-vine propagules (CVP) were covered with an eighth inch of a sand/peat mix. Fertilizer applications were made on 10-day intervals starting on June 28, alternating between 5-15-30 and 5-0-0, at a rate of 150 lb./acre. Irrigation consisted of misting every hour between 9am and 7pm for the first six weeks. Plots were hand weeded every 10 days. Each of the ten treatments was replicated six times. The auxin was applied as a preplant dip at a rate of 10mg/L (1.33x10-3oz./gal) for 24 hr. On August 15, 2002, number of propagules and uprights were counted and canopy height was measured. The cytokinin application was made on Sept. 6, 2002, via a product called VBC-30001 at a rate of 28.7ml/m2 (3.07gal/acre). Unfortunately, the disease Phyllosticta leaf spot (Phyllosticta spp.) caused severe damage to the planting during late summer and fall 2002. On May 14, 2003, a percent plant cover rating was made.

Significant differences were found among the establishment methods (Table 2 and Figure 9). The conventional method (uncut vines spread at a density of 1 ton/acre) had the fewest uprights and propagules, compared with all cut vine plots. The pre-plant auxin dip had a positive effect at the 1.5 ton/acre rate of CVP but not at the 0.5 ton/acre rate. As expected, the higher density of cuttings resulted in more uprights and propagules. No significant differences were seen in canopy height. In May 2003, percent plant cover was lower with the conventional planting method compared to CVP at the 1 ton/acre rate, and percent cover increased with increasing planting rate. There was no longer any effect from the auxin dip, and no effect was found from the September cytokinin treatments.

Cytokinin Greenhouse Study - Studies with other plant species have found that treatments with the plant growth regulator, cytokinin, can enhance shoot initiation and lateral branching by breaking apical dominance. During the establishment period of a new cranberry bed, increased shoot growth could result in the bed filling in more rapidly. Therefore, to study the possible effect of cytokinin on cranberry, plants were sprayed with a solution of benzyl adenine (B.A., a form of cytokinin) and monitored for shoot growth. Mature plants growing in 4”x 4” pots of Ben Lear & Stevens were treated on April 2, 2003 with four rates of BA: 0, 100, 200, & 400 mg AI/Liter (the 200 mg AI/L rate was similar to the rate applied in the field in 2002). Plants were sprayed until runoff. After treatment, the pots were arranged in a completely randomized design on a greenhouse bench, with ten replications of each treatment and cultivar. For the first 48 hr after treatment, watering was done by hand, watering the soil only. After one week, phytotoxicity was observed on the treated plants and leaf damage was assessed using a 1-5 rating scale, where 1=no damage and 5=50-75% damage. The total number of live growing tips on each pot was counted weekly for five weeks, April 10 – May 9, and then again on June 6 and July 11.

The leaf damage observed was correlated with B.A. applications, with most of the damage occurring at the growing tips. The 400 mg-treated plants had over 50% of their growing tips damaged, compared to almost no damage on the 0 mg-treated plants (Table 3). The 400 mg-treated plants also had the lowest counts of growing tips, probably because of the phytotoxicity. However, even at the lower B.A. treatment levels, no benefits were derived from these cytokinin treatments. In fact, on May 2 and May 9, for the cultivar Ben Lear, pots with no B.A. application had significantly more growing tips then any of the B.A. treated pots. Within the cultivar Stevens, no significant differences were found between B.A. treatments in number of growing tips.

Effect of establishment method, herbicide, and fertilizer on rate of establishment –
The objective of this trial was to compare two bed establishment methods, and evaluate the effect of herbicide and fertility level on establishment. The conventional planting method was planted by hand spreading the vines over the plot area and ‘pressing’ them in with a 3’ walk-behind disk. The alternative planting method used cut-vine propagules, chopped and spread by the prototype ‘cutter/spreader’ machine and then topdressed with a ¼” sand/peat mix. Both methods were planted at a rate of 1 ton/acre. Ten 3’ x 60’ strips were planted, each strip divided in half to compare the two establishment methods. A different cranberry selection was used in each strip so that preliminary information could be gathered on varietal differences in establishment.

Each planting strip was subdivided further into eight 3’x 7.5’ plots, to compare with and without pre-emergent herbicide (Devrinol 10G), and high and normal fertility levels, on both the conventional and alternative plantings. Devrinol 10G was applied to the H+ plots on July 2, three weeks after planting, at a rate of 3 lb a.i./acre. The two fertility levels used were 40 lb N/A/year (normal) and 80 lb N/A/year (high). Six applications were made at 10-day intervals (June 25, July 9, 18, 28, Aug 6, 15), alternating between ammonium sulfate (5-0-0) and a complete fertilizer (10-10-10).

The field trial was planted on June 10, 2003. The field had been fumigated on May 20, 2003. Super triple phosphate (0-46-0, 50 lb/A) was applied to all plots June 25. The plots were irrigated hourly, 10 min/hr from 9AM to 6PM for the first eight weeks; thereafter, as needed, usually 3 times per week. Poast herbicide was applied to the whole trial on August 7 for grass control. All plots were hand weeded in late July to make analysis of cranberry growth possible. Therefore, the effect of weeds on cranberry growth can’t be analyzed, only the effect of herbicide on cranberry growth. On August 11, 2003, percent plant cover was estimated, and the number of growing tips per 12.6 sq. in. was counted. On August 14, infrared photos were taken to determine vegetative index values (NDVI).

The August 2003 evaluations indicate no significant differences in the two establishment methods (Figure 10). In addition, no differences were found between the H+ and H- plots, indicating that Devrinol had no adverse effects on establishment. The high fertility plots had a significantly higher vegetative index, but little difference in % cover or number of growing tips. Considerable variation was found among the ten cranberry selections used, indicating that establishment rate should be evaluated when developing new cranberry varieties. Multiple selections from two different families were included in the trial and when their performance was compared, one family showed consistently better establishment than the other.

Additional counts of growing tips on September 29, 2003, and % cover ratings on June 21, 2004, found similar results: no difference between planting methods (Conventional: 14.2 growing tips, 39% cover; Alternative: 14.3 tips, 34% cover), no effect of higher fertility rates, and large differences between selections. These results suggest that the alternative planting method using cut vine propagules does not offer any advantage in speeding up the establishment period. Apparently too many of the cut stolon segments fail to become established. This trial will be evaluated over the next couple of years to determine if establishment method has any impact on cranberry yields.

Replicated Variety Trial – In order to address the final objective of this project, a replicated variety trial was established on June 16, 2003. It includes several standard varieties, as well as 77 of our most promising selections chosen from over 9000 progeny in six evaluation trials. These selections have higher yields, better color and potentially better disease resistance and other value added traits. Each selection was replicated three times in a randomized complete block design, and each 10 x 10 ft plot was planted with 96 rooted cuttings. Establishment ratings on Oct. 20, 2003 indicate significant differences among selections, although the ratings are partially a reflection of the size of the rooted cuttings at planting. This replicated trial will allow more accurate performance data to be collected, and allow growers to observe several potential new varieties and compare them with standard varieties.

Evaluation of new varieties in commercial production beds - Two selections, NJS95-32 and NJS95-37, were planted in production beds at Pine Island Cranberry Co., Chatsworth, NJ in 2001, for evaluation under commercial management. NJS95-32 has potentially the highest total anthocyanin (TAcy) of any variety in the Rutgers program. TAcy is a measure of the color of the berry, which is important because growers get a premium for darker berries. NJS95-37 has higher TAcy than either Stevens or Ben Lear, and yield comparable to Stevens. Although the beds have not filled in completely, preliminary data was collected in 2003. When compared with a Ben Lear planting in an adjacent bed, blooming periods are similar, with NJS95-32 being slightly earlier, NJS95-37 has a higher yield, and both selections have higher TAcy (Table 4).

Five of our most promising selections (CNJ93-20-151, CNJ93-21-131, CNJ96-44-83, CNJ95-20-20, CNJ97-105-4, NJS98-23) were planted in half-acre production beds at J. J. White, Inc., Browns Mills, NJ in November 2003, and a sixth selection was planted in May 2004. A total of 108,000 rooted cuttings were planted at 1 ft. intervals. In the fall 2004, a seventh bed will be planted with an additional promising selection, NJS98-35. A one-acre planting of a promising ‘white’ variety, CNJ93-21-131, was made at Pine Island Cranberry Co. in April 2004. All these plantings will be managed under a typical grower’s maintenance regime and allow growers to see for themselves the performance of these potential new varieties.