Fruit thinning, branching, and stop-drop of pears
Fruit thinning, branching, and stop-drop of pears otankWritten by: Win Cowgill, Win Enterprises LLC
Chemical fruit thinning
Some general comments on chemical fruit thinning of pears, including Asian pears:
- use/calculate diltue tree volume, which is typically 100 to 200 gallons per acre for pears; then
- when applying chemical thinners, use the table rate below per 100 gallons (dilute TRV)
- dilute (1X), up to 2X concentration works best with chemical thinners, do not exceed 4X concentration
- if spraying concentrate, also concentrate the thinning chemical as you would any other pesticide application
- apply chemical thinners when the temperature is rising into the 70's or low 80's and will remain there for 3 to 4 days
- for Aian pears, apply chemical thinners when largest fruits are 10 to 14 mm in size; 6-BA (Maxcel, Riteway, Refine) at 200 ppm (high rate) has worked good on Hosui and Kosui Asian pears in trials, however, Asian pear varieties differ in their sensitivity to chemical thinners
- for more detailed information, see the following publications
Cost-Effective Asian Pear Thinning for Productivity and Fruit Quality Fact Sheet
Spray Mixing Instructions Considering Tree Row Volume - TRV
timing | product | concentration | rate | comments |
---|---|---|---|---|
5-7 days after petal fall | Amid-Thin W (NAD) | 10 to 50 ppm | 1.6 to 8 oz per 100 gal | Label specific for use on Bartlett and Bosc. |
14-21 days after full bloom | Fruitone-L, PoMaxa, Refine 3.5 WSG | 10 ppm | 4 to 8 oz per acre | Apply as soon as fruit set is apparent and weather favors chemical thinning efficacy. Late applications may result in pygmy fruit. Apply when temperature is 70 to 75 F. Thinning efficacy depends on variety. |
fruit size 8-14 mm (7-28 days after bloom) | Maxcel, RiteWay | 75 to 200 ppm | 80 to 128 fl oz per 100 gal | Start with 150 ppm for Bartlett, 75 ppm for Bosc. Apply when temperature is 60 to 85 F. See comments. |
fruit size 8-14 mm (7-28 days after bloom) | exilis Plus | 75 to 200 ppm | 46 to 122 fl oz per 100 gal | See comments |
fruit size 8-14 mm (7-28 days after bloom) | exilis 9.5 SC | 75 to 200 ppm | 9.6 to 25.6 fl oz per 100 gal | See comments |
fruit size 5-20 mm | ProtoneĀ® | 100 to 500 ppm | 6.6 to 33.1 oz per acres | Make 1-2 application, but one application during a period of carbohydrate deficit is usually sufficient. ProtoneĀ® may be a particularly good pear thinner. |
Timing | product | concentration | rate | comments |
---|---|---|---|---|
BEFORE buds break in spring on 1-year old wood | Maxcel, Promalin; exilis plus, exilis 9.5 SC | 5,000 ppm | see label | If dormant buds are present on one-year-old wood only. DO NOT apply after bud break. See product labels for more details and instructions. |
AFTER bud break in spring on 1-year old wood | Maxcel, Promalin; exilis plus, exilis 9.5 SC | 500 ppm | see label | If buds have broken, and the leaf tissue is showing on one-year-old wood. Apply by spraying with a back-pack sprayer. Works best when temperatures are warm and there is enough tissue to absorb the PGR. Note: Never add surfactant to a solution of MaxCel as it is already included in the formulated product. Promalin should be combined with a NIS following the label instructions. |
For more information on branching young trees, see the UMass Fact Sheet F-140 Branching Young Apple Trees with Plant Growth Regulators
tming | product | concentration | rate | comments |
---|---|---|---|---|
7-14 days before anticipated harvest | ReTain | NA | 333 g per acre (one pouch) | Apply in sufficient water for good coverage. Add organosilicone surfactant at 12 oz per 100 gallons. |
5-7 days before harvest | Frutone-L, PoMaxa, Refine 3.5 WSG | 10 to 15 ppm | 4 to 6 oz per 100 gal | Apply 7 days before harvest to D'Anjou, Bosc, Bartlett. Make separate sprays to early, mid, and late varieties. |
5-7 days before harvest | Refine 24.2L | NA | 2 to 4 fl oz per acre | Bartlett, Bosc only. Effective in 3-4 days after application and controls drop for 2 weeks. |