Publication 360, Guide to Fruit Production:
Vegetative Growth Control in Apples

Excerpt from Ch. 4, Publication 360, Guide to Fruit Production 2012-2013,

Order this publication

1. Vegetative Growth Control in Apples
• Time of Application and Rates
  • Figure 4-5. Diagram Indicating Bourse Shoot Development
• Table 4-21a. Suggested Apogee Rates and Timings
• Table 4-21b. Suggested Apogee Rages - g Apogee/ha
• Orchard and Environmental Factors
• Adjuvants and Hard Water
• Precautions when using Apogee
2. Other Information on Growth Regulators and Thinning
   • Promalin to improve fruit shape
   • Ethephon to promote fruit colouring
   • Chemical control of preharvest drop
   • Recommendations for the use of ReTain
   • Preventing heat stress and fruit sunburn with Surround
   • Chemical Thinning of Apples
3. Other Information on Apples
   • Apple Growth Stages
   • Apple Nutrition
   • Apple Calendar
   • Guidelines for Protecting Non-Bearing Apple Plantings
   • Notes on Apple Diseases
   • Table 4-7. Products Used on Apples
4. Chapter 4: Apple Calendar - PDF 357 kb
5. Related Links
   

• reduce shoot growth by 20-60% and diminish the time required to dormant prune and/or summer prune
• lead to improved fruit colour on red-coloured cultivars
• result in a more open tree canopy, which will improve spray coverage
• reduce the incidence and severity of fire blight on shoots, but not blossom blight infections

• for medium to high vigour trees, apply 45 g product per 100 L of dilute spray (125 ppm)
• for low to medium vigour trees, apply 27 g product per 100 L of dilute spray (75 ppm)

^* Make the first application when terminal shoots are no longer than 2.5-5.0 cm, which usually corresponds with late bloom to petal fall. This will vary with tree growth and development in your area and by cultivar. These are approximate dates in southwestern Ontario. Growers with orchards in other areas should note the appropriate tree phenology stage to time these applications correctly.

Table 4-21b. Suggested Apogee Rates and Timings Based on Tree-Row Volume Dilute of 1,000 L/ha- g Apogee/ha (use this chart in conjunction with the product label.)

(based on 1000L/ha Tree-Row Volume (TRV) Dilute)⁴

+- Suggested base rate. Move to next higher or lower level based on factors listed below.

^* Shaded cells show the suggested base rate. Move to next higher or lower level based on factors listed below.
¹ Make the first application when terminal shoots are no longer than 2.5-5 cm, which usually correspond with late bloom to petal fall. This will vary with tree growth and development in your area and by cultivar. These are appropriate dates in southwestern Ontario. Growers with orchards in other areas should note the appropriate tree phenology stage to time these applications correctly.
² Vigour is defined as the total amount of shoot growth in a single season. Not to be confused with tree-row volume.
³ Tree-row volume (see OMAFRA Factsheet, Adjusting, Maintaining, and Collaborating Airblast Sprayers, order no. 10-069, for more details). Rates need to be increased when higher water volumes are required for adequate spray coverage.

⁴ Maximum seasonal rate should not exceed a total of 5.4 kg of Apogee.

Orchard and Environmental Factors to Adjust Apogee Rates and Number of Sprays

 

Heavy Dormant Pruning	increase rate by 10-20% per ha per spray
Longer Growing Season	add 3rd or 4th spray
Low Crop Load	Move Apogee program to next higher level
Questionable Coverage	Move Apogee program to next higher level
Fire Blight Suppression	Move Apogee program to next higher level or apply (650 g/1,000 L)initial rate

Adjuvants and Hard Water

Include the spray adjuvant, Agral 90, with Apogee to improve the uptake of the prohexadione-calcium molecule by the leaf. In addition, if the spray water source is hard water and contains high levels of calcium or magnesium, include an equal amount of ammonium sulphate (AMS) fertilizer by weight with Apogee. Use a high-quality, greenhouse grade of AMS to avoid plugging of nozzles. Obtain water hardness ratings from your municipal water supplier, or have well water tested for hardness. Consult www.ene.gov.on.ca/en/water/sdwa/licensedlabs.php for a list of accredited labs that conduct these tests.

Precautions when using Apogee

In some instances, Apogee may increase the strength of fruit set and make thinning more difficult. This response is not consistent but is more likely at concentrations above 125 ppm (45 g/100 L). Apogee-treated trees may require more aggressive chemical or hand thinning to reduce the crop load to the desired level.

Apogee can cause severe cracking on Empire and Stayman cultivars as stated on the product label. The cause is unclear, but may be related to environmental conditions. Reports of cracking damage of Empire when Apogee has been used are increasing. Compliance with the label is strongly advised. Apogee may result in decreased yield and marketable yield of Cortland. Despite this, clear benefits of the use of Apogee on tip bearing cultivars such as Cortland and Northern Spy have been observed in other regions of Canada where the shortened internodes of Apogee treated trees has produced a more compact tree habit.