Root response in Pyrus calleryana ‘Chanticleer’ treated with two liquid Nutri-Root and Root-jet formulations Joseph J. Doccola, Director of Research & Development, Arborjet, Inc. Woburn, MA Summary A rooting study was conducted with balled and burlapped (B&B) Pyrus calleryana ‘Chanticleer’ (Chanticleer pear) to investigate the effects of liquid formulations comprised of varying percentages of surfactant, humectants, kelp, and humic acid with and without a fertilizer component. The trees were 4.4 cm (1.75 inch) caliper, machine dug with root balls averaging 50 cm (20 inches) across. The trees were placed above ground and mulched with shredded hemlock. The treatments were (A) Nutri-Root, (B) Root-jet, and (C) Check. Each was replicated 6 times. Treatments were administered once per month, where each received 40 mLs concentrate in 3.785 L (1.05% solution), except for the checks which received 3.785 L of water only. The study continued for 16 weeks after which the mulch was removed and all the roots extending from the root ball were cut, washed clean of debris and weighed. Trees treated with Nutri-Root established the highest density of roots of 108.1 ± 31.0 g compared to Root-jet alone of 79.3 ± 18.5 g or to the checks with 40.2 ± 11.0 g. The Nutri-Root treatments developed 1.4 to 2.7 more root weight compared to the other treatments. Key words Transplant, root loss, water stress, water management, surfactants, humectants, root growth Introduction Increased tree transplant survival has been attributed to mechanical tree harvesting of B&B trees (Desmarteau, 2002). Even so, root loss of B&B stock is appreciable and may be on the order of 95%. The finely branched non-woody roots that extend beyond the canopy whose function is to absorb water are left behind in the nursery. It can take as much as 7 weeks for new callus to be initiated and 13 to 20 weeks before newly formed roots can absorb any significant amount of water outside the rootball (Watson, 1991). The reduced root mass imposes water stress on the tree (Kozlowski and Davies, 1975). Although trees are generally dug prior to bud break when water demand is low, the demand increases with foliar growth. Water supply must meet the water lost from stomates and lenticels for trees to survive. B&B trees also have to tolerate sitting above ground in the nursery for extended periods of time, sometimes the entire growing season, before being re-planted. This holding condition is not favorable to root development. Techniques that minimize water stress and aid root development will favor tree survival. Water applied to thoroughly wet the root ball is an obvious, necessary strategy; however, irrigating rootballs is at best inefficient as run-off may be appreciable. If the holding period is long (for example, the entire growing season), the application of mulch around the root ball is a useful technique to reduce water loss from the tree. Mulches form a barrier to evaporative loss, keeping

the root ball moist. They also create an environment into which roots are capable of growing. The research literature supports that (1) water is most crucial to tree survival, (2) that organic amendments help to improve soil structure, and (3) fertilization is best used after establishment. A search of the literature documents the use and role of irrigation, hydrogels, biostimulants, growth regulators, mulches, and organic amendments in tree planting. Research supports the use of organic and inorganic amendments into the planting bed (Banko, 1986, Bir and Ranney, 1991), though these primarily function to improve soil structure. Ferrini and Nicese (2002) examined the effects of biostimulants including marine algae, humic acids and yucca extracts to promote establishment of English oak (Quercus robur L), particularly in poor soils. Gilman (2004) evaluated the use of soil amendments (paclobutrazol, hydrogels, humic substances) around the root ball following planting of live oak (Q. virginiana Mill.) was compared to frequent and infrequent watering. In that study, Gilman found that irrigation was critical to survival of the newly planted trees and more frequent irrigation was more efficacious compared to less frequent watering. However, he did not find that the amendments used were of any benefit to tree transplant survival. Paclobutrazol, in other studies, has been shown to reduce shoot length and encourage root development (Watson, 1996, 2004; Watson and Himelick, 2004). Richardson et al. (2004) investigated stress responses in paper birch (Betula papyrifera Marsh.) and the effects of organic biostimulants (ascorbate, B-vitamins, vitamin E, casein hydrolysate, humic substances and marine algal extracts), previously shown to enhance growth and drought stress tolerance in plants. Ferrini et al. (2005) studied the effects of compost, humic substances and fertilization on newly planted Q. robur. In that study, the researchers conclude that the first year was most critical following planting to tree survival, and suppression in growth (which was the primary parameter measured) reflected root loss, typical of the condition of newly transplanted trees. The authors agree that critical to initial establishment of the tree is an adequate water supply, followed secondarily by fertilization, which was of greater importance subsequent to tree establishment. The study found that leonardite and compost positively affected macroporosity, thus improving soil structure. Percival and Fraser (2005) applied 70 g/L sucrose to improve transplant success of birch (Betula pendula Roth) and reporting positive results. Costello et al (2005) investigated the effects of irrigation on the growth of several native California oak species including Q. lobata Née, Q. agrifolia Née, and Q. douglasii Hook. & Arn. following (1 yr) establishment. Scharenbroch and Lloyd (2006) examined the effects of organic matter, microbial biomass, and nitrogen availability in urban soils, where organic matter increased both microbial biomass and, as a consequence, nitrogen availability. Rivenshield and Bassuk (2007) reported the benefit of using organic amendments to improve soil porosity and root growth. Day & Harris (2007) evaluated fertilizers to improve the establishment and drought tolerance of red maple (Acer rubrum L.) and littleleaf linden (Tilia cordata Mill.), but reported no benefit at the recommended rate of 1.5 kg N/100m2. Montague et al. (2007) investigated the favorable effects of irrigation and mulch on the establishment of several woody shrubs species in Texas, including Forsythia x intermedia Zabel., Lagerstroemia indica L., Photinia x fraseri Dress., and Spiraea x vanhouttei (Briot) Zabel. In a review of factors affecting transplant

success of Q. rubra, Struve (2009) alludes to mixed benefits of biostimulants (plant hormones, humates, manures, and/or sea kelp extracts) as transplant amendments. Although several authors examined polymer gel additions to increase the water availability to roots after planting, no reference was found discussing the use of liquid surfactants and humectants substances to lower the surface tension and humidify the root ball prior to planting. Whereas hydrogels are hydrophilic(colloidal polymers which absorb and hold water, where water is the dispersing medium), humectants are hygroscopic substances that absorb moisture from the air. Common examples of humectants include propylene glycol, sugar alcohols, Aloe vera, and honey. Both function to manage water in the soil and rhizosphere. Where water and soil moisture holding capacity is limited, moisture managers such as surfactants and humectants may be useful, particularly in liquid form. They may also prove useful when trees have suffered root loss, such as when they are newly dug and balled and burlapped. Liquid soil amendments may be administered directly to the root ball and will aid in keeping the root environment hydrated. The surfactant component functions to breakdown surface tension, so water can be more readily absorbed. In this study, we were interested in measuring tree survival and root development in Pyrus calleryana ‘Chanticleer’ (Chanticleer pear) over a growing season, using minimum water inputs and applying mulch and liquid formulations comprised of varying percentages of surfactant, humectants, biostimulants (kelp, and humic acids) with and without a fertilizer component. Methods A rooting study was conducted with machine dug and basketed, balled and burlapped (B&B) Pyrus calleryana ‘Chanticleer’ (Chanticleer pear). Eighteen (18) pears were 4.4 cm (1.75 inch) caliper, with root balls averaging 50 cm (20 inches) across. The trees were placed above ground with ~20 cm between rootballs for trees within a treatment. Bales of 70.8 L (2.5 cu ft) compressed pine wood shavings secured in place with re-bar to separate the treatments. All were mulched with natural shredded hemlock to 5 cm above the top of the root ball. The study was initiated on June 07, 2013 and ended on October 01, 2013. The treatments were (A) Nutri-Root (Arborjet, Inc. Woburn, MA, USA), (B) Root-jet (Arborjet, Inc.), and (C) Check. Nutri-Root is formulated with 22.0% humectants (derived from sugar alcohols, polysaccharides and neutral salts of alpha-hydroxypropionic acid), 4.0% non-ionic surfactant (derived from coconut oil), biostimulants (4.0% north Atlantic kelp, and 2.0% humic acid derived from potassium humate) plus a fertilizer component of 2.0% nitrogen (derived from urea and water soluble nitrogen), 2.0% phosphate and 3.0% potash (derived from mono-potassium phosphate), plus microelements, 0.75% iron (derived from ferrous sulfate), 0.50% manganese (derived form manganese sulfate) and 0.25% zinc (derived from zinc sulfate). Root-jet is formulated as a 2-4-4 fertilizer plus 2.0% iron and 1.0% manganese. Each was replicated 6 times. Treatments were administered once per month, where each tree received 40 mLs concentrate (of A or B) in 3.785 L, except for the checks which received 3.785 L of water only. The study was continued for 4

months after which the mulch was removed and the new roots extending from the root ball were cut, washed clean of debris, air dried and weighed. The excised roots were placed in a series of 9 water baths until all the debris was removed, before air drying and weighing. Data was obtained from the National Weather Service for Concord, NH (latitude 43 12 N, longitude 71 30 W), the closest reporting station to the study site. We used 2.5 cm (1 inch) per week as the guideline for irrigating trees. When natural rainfall fell below this point, supplemental water was administered to all the trees at 3.785 L (1 gal.) per tree. Statistical analyses were conducted in MINI-Tab v15 (State College, PA), where significance was accepted at p=0.05 at the 95% CI. Results The average high temperature during the 4 month growing period was 78.9°F (Table 1). The average precipitation was above normal for the months of June, July and September, but below normal for the month of August (Table 2). The second and third weeks in August were particularly dry; supplemental water was administered to relieve the deficit. Table 1. 2013 Monthly Temperature Data for Concord, NH Month JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC YEAR

AVG High 33.4 33.3 42.5 58.5 71.0 77.9 84.2 80.1 73.4 62.3 45.7 32.3 57.9

AVG Low 12.2 17.0 23.2 32.0 42.4 54.0 62.3 53.6 45.8 35.7 25.1 14.7 34.8

Mean Temp 22.8 25.2 32.9 45.3 56.7 66.0 73.3 66.9 59.6 49.0 35.4 23.5 46.4

Table 2. 2013 Monthly Precipitation Data for Concord, NH Month JAN FEB MAR APR MAY JUN JUL

Precipitation 1.55 3.54 1.72 1.88 4.07 6.78 6.70

Departure from Normal minus 1.15 plus 0.92 minus 1.55 minus 1.53 plus 0.41 plus 3.09 plus 2.96

Departure from Normal plus 2.2 plus 0.9 minus 0.2 plus 0.2 plus 0.9 plus 1.1 plus 3.3 minus 1.6 minus 0.4 plus 0.8 minus 2.9 minus 3.3 none

AUG SEP OCT NOV DEC YEAR

2.05 4.81 1.28 3.02 3.39 40.79

minus 1.13 plus 1.43 minus 2.76 minus 0.70 plus 0.19 plus 0.18

No tree died in the study and all the trees initiated new roots extending beyond the rootballs. Trees treated with Nutri-Root established the highest density of roots of 108.1 ± 31.0 g compared to Root-jet alone of 79.3 ± 18.5 g or the checks with 40.2 ± 11.0 g. None of the treatments were statistically different from one another due to the variation observed among treatments, but the differences may have biological significance. The Nutri-Root treatments developed 1.4 to 2.7 more root weight compared to the other treatments. The mean root weights per treatment are presented in figure 1. Mean ( g fresh wt ) of Pyrus calleryana New Root Growth 120 108.117

Mean of g fresh wt

100 79.3333

80 60

40.2

40 20 0

Nutri-Root

Rootjet TRT

untreated

Figure 1 mean grams fresh weight of new roots cut from the root balls of B&B Pyrus calleryana ‘Chanticleer’ 16 weeks after treatment.

Figure 2 photographic scans of the best root development per treatment, from left, Nutri-Root, Root-jet and water only at 16 weeks.

Discussion & Conclusions No treatment tree died during this study. The Nutri-Root treatments had the greatest density of roots by weight. We believe that root development was enhanced by several factors primarily, the presence of surfactants and humectants in the liquid formulation. The marine kelp extract may have aided root development as this product is a source of cytokinins, an auxin associated with cell division (cytokinesis) and root morphogenesis (EPA.gov factsheet 4107). When the root balls were watered using a watering can, the check trees tended to shed the water from the root ball, whereas the Nutri-Root and Root-jet trees absorbed the liquid quite easily. The presence of surfactant to enhance water absorption may have played a biologically significant role in root development in this study. Additional studies are being conducted to assess the long term benefits of tree growth using Nutri-Root.

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