Publication 360, Fruit Production Recommendations: Ethephon to Promote Fruit Colouring in Apples

Excerpt from Ch. 4, Publication 360, Fruit Production Recommendations 2010-11,

Order this publication

1. Ethephon to promote fruit colouring
2. Other Information on Growth Regulators and Thinning
   • Promalin to improve fruit shape
   • Chemical control of preharvest drop
   • Recommendations for the use of ReTain
   • Preventing heat stress and fruit sunburn with Surround
   • Apogee for vegetative growth control
   • 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

Ethephon (Ethrel) has the following effects on trees and fruit, depending upon the timing and rate of application:

• Ethrel stimulates ripening, colour development and fruit drop. To prevent excessive premature drop after the use of Ethrel, apply a suitable stop-drop product such as naphthaleneacetic acid (NAA). Two applications are required: one as a tank-mix at the time Ethrel is applied and the second five days later. Apply the stop-drop at the normal rate recommended on the label.
• Spray just the number of trees that can be harvested over a 2-3 day period. Depending on cultivar and air temperature, fruit will be ready to harvest 5-10 days after the spray is applied. After a spray, check the maturity of the apples on a daily basis for pressure, starch, flavour and colour. A few trees sprayed at 3-4 day intervals are easier to manage than a large number sprayed at one time. Make sure a market is available for the treated apples before you spray, especially with early cultivars.
• Rates of application depend on cultivar, date of application, tree vigour, temperature, weather conditions and degree of response required. Early cultivars like Jerseymac and Paulared, which ripen under warmer conditions, require less material than later cultivars. On early cultivars, use 0.75-1.5 L of Ethrel per ha with sufficient water to wet the trees thoroughly. McIntosh requires 1.5-4.25 L/ha. Use the higher rate early in the season on trees high in nitrogen or on poorly pruned trees. Use lower rates on young, well-pruned trees or on trees low in nitrogen. Best results are obtained when Ethrel is applied 2-3 weeks before harvesting. Be sure to apply Ethrel uniformly, since it works only where the spray touches.