As the first step in pre-harvest planning, tree nutrition should be a top priority. Maintaining optimum calcium levels helps maintain fruit firmness and reduce bitter pit, while proper potassium levels can help fruit size and color development. Keeping micronutrients at correct ranges will help round out top tree nutrition needs. At this time, watch for things like watercore, which is suspected to occur when the ratio of nitrogen to calcium is too high, resulting in water retention in apples. Another key stressor is heat and sun, which may significantly impact fruit quality--use of sunburn protectants such as shade cloth, evaporative cooling and sprayable protectants reduce the risk. It is also important to treat for insects and diseases that may be present.
As harvest approaches, ethylene is the top factor in determining fruit maturity and the picking timeline. As apples near maturity, they begin to increase respiration and evolution of ethylene. The hormone stimulates production of enzymes that break down cell walls in the apple stem, leaving fruit connected by only the vascular strands which are easily broken. This is the final step before apples are ready for harvest and should be monitored closely. As this process begins, it is important to determine if you need plant growth regulators (PGRs) to reduce pre-harvest fruit drop, advance or slow maturity and stage harvest.
Since apples in an orchard block may mature at different times, PGRs can help manage this process. Plus, the loss of storability and shelf life later down the line are at risk when quality isn't managed at this time.
Lengthening the Picking Window:
Apple harvest timing is hard to nail down, with quality-loss for harvesting too early or too late. Having more control of the picking window allows you to harvest on your schedule and better manage your crews and timeline.
Plus, lengthening the harvest window with a PGR leads to increased fruit size without quality loss, longer hanging fruit time without losing firmness, improved consistency from tree to tree and fewer disorders such as watercore, greasiness and stem bowl cracking. And, PGRs can be used throughout the season and usually require no special equipment.
Create a Plan:
Ask yourself these questions to determine your harvest window needs.
Visit the ReTain® Plant Growth Regulator Soluble Powder product Webpage for more information on how ReTain can help you run harvest on your schedule.
Always read and follow label instructions.
* First published by the U.S. Apple Association as part of their Thought Leadership series. Republished on the permission of the U.S. Apple Association.