integrated weed control for organic apple orchards...(stefanelli et. al, 2009); and weed density and...

Integrated Weed Control for Organic Apple Orchards

Canopeo app

Fig. 1: Raw photo and Canopeo analysis of sample relevés, taken on iPhone 2017/5/10 by David Zakalik

Top: Cultivation+Final San-O. 16.06% cover Bottom: Cultivation + Mowing. 84.51% cover

Effective weed control in organic orchards is among the greatest challengesfaced by apple growers.

Previous experiments have assessed the effects of different organic-certifiedapple orchard floor management systems (OFMSs) on tree growth and yield(Stefanelli et. al, 2009); and weed density and weed diversity (Ustuner &Ustuner, 2001; Tasseva, 2005; Lisek & Sas-Paszt, 2015).

Few studies have characterized and compared the effects of different organicOFMSs on weed mass and cover specifically, let alone changes in theseparameters over time. The recent advent of the Canopeo app (OSU, 2015)has made assessment of weed cover fast, simple, accurate, and precise.

We are conducting a long-term phytosociological and soil-health study oforganic apple OFMSs. Begun in 2016 and continuing in 2018, this study aimsto investigate the effects of organic OFMSs on soil health, weed cover andmass, foliar nutrition, tree growth, weed biodiversity, and prevalence ofindividual weed species, over four-month seasons.

Experimental Design• Randomized complete block, split-plot• 12 treatment combinations × 4 blocks =

48 repetitions, ~5-8 trees each.• 8 rows of ‘Honeycrisp (Firestorm)’/‘B.9’

trees treated as follows:

Main treatments, ~36-40 trees each:Bare soil, Cultivation, Mulch

Sub-treatments, ~5-8 trees each:Control, Mowing, Suppress, Final-San-O

• Mulch applied in early June 2016; notreapplied

• Cultivation, mowing, and herbicideapplied once monthly June throughAugust 2016

Weed cover: Suppress and Final-San-O plots had significantly(p<0.001) lower weed cover than mowed plots, across allmain treatments. Mulched plots had significantly (p<0.001)lower weed cover than Bare-Soiled or Cultivated, across allsub-treatments. Time had a significant effect (p<0.001) onweed cover across all treatments.

Total weed biomass: Suppress and Final-San-O and Mowingwere all equally effective in reducing overall weed masscompared to control. Mulched plots had significantly(p<0.001) lower weed mass than Bare-Soiled or Cultivated,across all sub-treatments. Time had a significant effect(p<0.05) on weed cover across all treatments.

Table 2. Four-month dry-mass averages of top 11 weed species by main and sub-treatments.

Weed taxon biomass: Masses of five top taxa were significantly affected by time:Grasses, Plantago major, Prunella vulgaris, Taraxacum officinale, and Trifoliumrepens. With the exception of P. vulgaris, the effect of time on these taxa’sbiomass is attributable to either average monthly air temperature or totalrainfall.

Climatic effects: Total weed biomass and Shannon Diversity Index bothsignificantly affected by total monthly rainfall (p=0.022 and p<0.001,respectively). Weed Cover significantly affected by average monthly temperature(p<0.001).

Tree growth: Mulch and herbicide sprays had a significant (p<0.001) positiveeffect on tree growth in 2016. In 2017, mulched trees again grew more than treesin bare or cultivated soil.

Soil health: Mulch had a strong positive impact on all soil health parametersexcept soil pH and Zinc. Superficially cultivated plots had slightly higher organicmatter and soil protein than bare-soiled plots.

ReferencesLisek, J. Synanthropic orchard flora in West Mazovia—Central Poland. Journal of Fruit and Ornamental Plant

Research, 2012, 20(2): 71-83.Lisek, J. & Sas-Paszt, L. Biodiversity of weed communities in organic and conventional orchards. Journal of

Horticultural Research, 2015, 23(1): 39-48.OSU: Patrignani, A. and Ochsner, T.E., 2015. Canopeo: A powerful new tool for measuring fractional green

canopy cover. Agronomy Journal, 107(6), pp.2312-2320.Stefanelli, D., Zoppolo, R.J., Perry, R.L, & Weibel, F. Organic Orchard Floor Management Systems for Apple

Effect on Rootstock Performance in the Midwestern United States. HortScience, 2009, 44(2): 263-267.Tasseva, V. Species composition of weed vegetation in different apple growing technologies. Notulae

Botanicae Horti Agrobotanici Cluj-Napoca, 2005, 33: 59-64.Ustuner, T. & M. Investigation on different mulch materials and chemical control for controlling weeds in

apple orchard in Turkey. Scientific Research and Essays, 2011, 6(19): 3979-3985.

Table 4: Fall 2017 soil analysis results.

After two years, mulch appears to enhance weed suppression, suppress weedbiodiversity, and promote tree growth and soil health. Mulch and herbicidesprays appear to be most effective in controlling weed growth. Another season’sanalysis will elucidate the effects of these organic weed management methods.

Weed biodiversity: Cultivation had the strongest positive effect on weed biodiversity.Mulch and Suppress herbicide had the strongest negative effects on weed biodiversity.Time had significant (p=0.002) effect on Shannon Diversity Index (SDI) across alltreatments.

Figs. 1a-1c: Average total relevé weed mass by treatment.

Figs. 2a-2c: Average relevé weed cover by treatment.

Figs. 3a-3c: Average relevé SDI by treatment.

Thirty weed taxa identified, 29 at species level; grasses treated as one taxon. Eleventaxa with highest total biomass ranked; 19 remaining taxa summed (Table 1).

Table 1. Top 11 weed taxa by biomass, summed across all months and treatments.

Species/TaxonRank by

total biomass

Grasses 1Taraxacum officinalis 2Plantago lanceolata 3Solidago canadensis 4Ranunculus bulbosus 5Cirsium arvense 6Cichorium intybus 7Plantago major 8Prunella vulgaris 9Linaria vulgaris 10Trifolium repens 11All others N/A

• Cultivation, mowing, and herbicide applications repeated in May, June,July, and August 2017, after weed samplings.

• ¼-m2 relevés under trees chosen randomly; no relevé sampled twice• Relevés assessed for weed cover using the Canopeo app• All above-crown weed foliage within relevés cut, sorted by species, and

dried for seven days at 70°C• Weeds sampled once monthly in the second weeks of May through August

(exact dates in Figs. 1-3)

Tree trunks measured 30 cm above graft union in Spring 2016, Fall 2016, andFall 2017.

Investigators: David Zakalik; Mike Brown; Gregory PeckSchool of Integrative Plant Science—Horticulture Section

Figure 4. TCSA over time, by Main treatment

Treatment,sub-treatment

% Change (Spring-

Fall 2016)

% Change (Fall 2016-Fall 2017)

Bare Soil 25.1 x 49.4 x

Untreated 22.0 B 36.2

Mowing 16.8 A 44.4

Suppress 34.6 C 55.0

Final San-O 33.0 C 56.9

Cultivation 27.9 x 43.1 x


Mowing 19.3 A 40.4



Mulch 37.0 y 57.3 y


Mowing 25.8 A 57.6



Main <0.001 <0.001

Split <0.001 0.532

Table 3. Change in TCSA, by treatment

Acknowledgements:

Toward Sustainability FoundationNYS Soil Health Initiative2016 and 2017 Cornell Orchard Interns

Biomass of individual weed taxa: 7 of top 11 taxa affected by main treatment, 6affected by sub-treatment, 2 affected by both main and sub-treatment. Main/subinteractions not significant.

Introduction

Procedure and Methods

Preliminary Results, 2016-2017

Conclusions/Further Study

Taraxacum

officinalis

biomass (g)

Trifolium

repens

biomass (g)

Biomass,

all other

species (g)

5.5 xy 1.0 y 1.8

5.7 0.9 3.5

2.3 0.6 1.8

6.0 1.0 0.7

8.0 1.4 1.2

7.6 y 0.2 x 2.9

5.7 0.1 4.9

6.7 0.1 2.0

6.2 0.1 2.6

11.6 0.3 2.1

3.0 x 0.5 xy 0.9

2.8 1.2 1.3

2.1 0.4 0.3

3.3 0.2 1.6

3.7 0.2 0.3

0.009 0.023 —

0.104 0.674 —

<0.001 0.022 —

Treatment,

sub-treatment

Cichorium

intybus

biomass (g)

Cirsium

arvense

biomass (g)

Grasses

biomass (g)

Linaria

vulgaris

biomass (g)

Plantago

lanceolata

biomass (g)

Plantago

major

biomass (g)

Prunella

vulgaris

biomass (g)

Ranunculus

bulbosus

biomass (g)

Solidago

canadensis

biomass (g)

Bare Soil 0.8 xy 3.1 7.5 y 0.2 x 8.1 y 0.7 1.3 y 1.7 5.7

Untreated 1.1 11.2 B 9.3 B 0.4 B 8.6 1.6 B 3.7 1.4 A 10.0 B

Mowing 0.3 0.5 AB 0.7 A 0.1 A 10.2 0.4 A 0.5 2.9 B 5.2 AB

Suppress 0.4 0.5 A 11.4 AB 0.0 A 8.1 0.3 A 0.3 0.0 A 1.3 A

Final San-O 1.6 0.0 A 8.6 AB 0.2 A 5.7 0.4 A 0.7 2.5 A 6.2 AB

Cultivation 2.5 y 1.2 6.3 xy 1.4 y 2.1 x 1.5 0.3 x 3.5 4.3


Mowing 0.6 1.8 AB 5.4 A 0.5 A 1.5 0.6 A 0.0 7.3 B 4.9 AB



Mulch 0.4 x 0.6 2.5 x 0.2 x 3.7 x 1.3 0.3 x 3.5 3.8


Mowing 0.3 1.0 AB 0.7 A 0.1 A 1.9 1.3 A 0.4 10.8 B 4.7 AB



Main 0.027 0.099 0.006 <0.001 <0.001 0.529 0.016 0.122 0.643

Split 0.319 0.012 0.011 0.001 0.055 <0.001 0.093 <0.001 0.018

Month 0.292 0.777 0.006 0.368 0.953 0.014 0.036 0.309 0.799

integrated weed control for organic apple orchards...(stefanelli et. al, 2009); and weed density and...

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