©2023 International Society of Arboriculture 66 All trees were subjected to an insecticide program using the residual pyrethroid insecticide deltame- thrin, where a 0.9-mL L-1 solution of deltamethrin was applied every 12 weeks commencing in May 2019 until September 2019. Insecticide sprays were applied using a 10-L knapsack sprayer, and trees were sprayed until runoff, which generally required 200 to 250 mL of insecticide solution per tree. Plant Vitality Assessments Measurements were made towards the cessation of the growing season (late September/early October) in both container (2018) and field (2019) trials. To keep the physiological age of the leaves comparable through- out the experiment, plant vitality measurements were made only on fully expanded, mature, green-leaf tissue. Leaf Chlorophyll SPAD Measurements A Minolta chlorophyll meter SPAD-502 (Konica Minolta, Inc., Tokyo, Japan) was used at the midpoint of the leaf next to the main leaf vein. In all cases, SPAD measurements were taken from 6 leaves (2 from the top of the crown, 2 in the centre, and 2 at the base) per plant. Leaf Chlorophyll Fluorescence Measurements were made on 10 leaves per tree. Mea- surements were performed using a pocket Plant Effi- ciency Analyser (PEA) device (Hansatech Instruments Ltd, Norfolk, England, UK). Following dark adaptation (30 minutes), the fluorescence response was induced by a one-second flash of light (650 nm, 1500 µmol m2 s-1) provided by an array of 3 light-emitting diodes over a 4-mm diameter of leaf surface. The ratio of variable (FV = FM – Fˆ0) to maximal fluorescence (FM) was cal- culated. The multi-parametric parameter known as per- formance index (PIABS) was also calculated in accordance with the calculations review by Banks (2017) with extrapolated Fˆ0 used. Scab Severity Scab severity of leaves and fruit was assessed visu- ally on September 28 and 29 in both container (2018) and field (2019) trials. Leaf scab severity of each tree was rated using a visual indexing technique and rat- ings on the scale: 0 = No scab observed 1 = < 5% of leaves affected and no aesthetic impact comparison, and a control, with 10 trees per treat- ment. Following potting, trees remained outdoors on a free-draining weed-suppressant fabric at the Bartlett Tree Research Site, Reading, Berkshire, England, UK (51°24'44"N, 01°56'18"W). Trees were subject to natural climatic conditions and watered as required. The experimental design adopted was a completely randomised block design. All trees were subjected to an insecticide program using the residual pyrethroid insecticide deltamethrin (product name Bandu) (Headland Agrochemicals Ltd, Saffron Walden, Essex, England, UK) where a 0.9 mL L-1 solution of del- tamethrin was applied every 12 weeks commencing in May 2018 to September 2018. Insecticide sprays were applied using a 2-L handheld pump sprayer, and trees were sprayed until runoff, which generally required 30 to 40 mL of insecticide solution per tree. Field Trials (2019) The field site was established in 2010 and consisted of a 100-m2 block planted with bare-rooted, standard Pyrus communis ‘Conference’ pear stock with a dis- tance of 2 m between trees. Trees were staked and given supplementary water until establishment (2 years). Trees had an average height of 1.6 m ± 0.25 m at the time of the experiment, with mean trunk diameters of 5 cm ± 1.4 cm just above the graft. The trial site was located at the Bartlett Tree Research Site, Reading, Berkshire, England, UK (51°24'44"N, 01°56'18"W). Weeds were controlled physically by hand and by using a hoe at 8 weekly intervals throughout the experiment. No supplemental watering or fertilisa- tion was applied during the trial. Historically, trees suffered from pear scab infection on an annual basis. The trees were inspected in September 2018, and only those with greater than 30% of leaves affected with scab infection were included in the trial that commenced in spring 2019. Treatments were assigned to trees using a completely randomised block design with 5 replicates and consisted of an industry com- parative fungicide spray of penconazole; a watered control; a chitosan or chitin top dressing soil amend- ment at 1.0% by volume; a soil-applied top dressing of crab meal; a soil-drench liquid chitosan; and a soil- drench chitin fertiliser (Agrinos 5-0-0). See Table 1 for full details. Fungicide application occurred at 4 growth stages (Bevan and Knight 2001), namely: bud break (March 9), green cluster (April 8), 90% petal fall (May 16), and early fruitlet (June 9). Percival et al: Chitin-Based Soil Amendments on Severity of Apple and Pear Scab
March 2023
| Title Name |
Pages |
Delete |
Url |
| Empty |
Ai generated response may be inaccurate.
Search Text Block
Page #page_num
#doc_title
Hi $receivername|$receiveremail,
$sendername|$senderemail wrote these comments for you:
$message
$sendername|$senderemail would like for you to view the following digital edition.
Please click on the page below to be directed to the digital edition:
$thumbnail$pagenum
$link$pagenum
Your form submission was a success.
Downloading PDF
Generating your PDF, please wait...
This process might take longer please wait
