Integrative physiology and modeling improves thinning and fruit development in apple

2007 Impact statement
  • Lakso, Alan Neil

abstract

The Apple Physiology and Culture program at Cornell has developed an integrated crop physiology approach with field experimentation and dynamic crop modeling that has substantially improved the understanding of the complex behavior of apple orchards and is optimizing the orchard management for better profitability.

submitted by

issue being addressed

Apple trees generally produce 10 to 20 times more flowers than necessary or desired for a commercial crop of quality apples. The production of too many fruits reduces fruit size and quality, and also reduces next year’s flower bud development in the early season giving low return yields in the subsequent year. However, carrying too few fruits will improve size but causes disproportionate reductions in yield, crop value and poor sustainability. Consequently, precise fruit thinning early in the season is an essential practice in apple production. Yet thinning responses are extraordinarily variable as many things cause fruit to drop including variable weather and tree health. After thinning, supporting fruit development to attain the potential desired fruit size and quality is critical as well. Yet variable responses to summer pruning and pest injury have been hard to understand.

response

Over the past 30 years many of the key components of tree and fruit growth, response to the environment, and response to chemical thinning agents have been studied. But it became apparent that the problem was to integrate the interactions amongst tree physiology, the environment and the thinning agent, with an emphasis on carbohydrate relations. This was done experimentally by using large clear plastic chambers that could enclose entire trees (photos available) but allowed the measurement of the integrated tree function in the field in relation to tree development, environment, pest stresses and cultural practices. A complementary approach has been to develop dynamic crop models of fruit crop carbohydrate relations to integrate our knowledge and make predictions of crop behavior under different conditions of tree health and environment.

impact assessment

By understanding the principles governing and the interactions amongst the key processes in fruit development and how environment and cultural practices modify them, we have made great progress in explaining many previously puzzling behaviors. Our model is being used by extension for teaching apple tree behavior as well as specifically providing real-time estimates of the system sensitivity to chemical thinners at the time of recommending thinning chemicals for each season. It is difficult to document dollar values of better fundamental understanding of a crop by growers and the avoidance of mistakes. However, profitability is very sensitive to the success of chemical thinning. Mistakes in thinning, either under or over-thinning, often reduce crop values by thousands of dollars per acre over more than one year. Finally, understanding how mid-season stresses and cultural practices affect pest management and final fruit quality has improved markedly, though again difficult to document quantitatively.

academic priority area

topic description

Fruit Crop Biology and Management

has geographic focus

funding source description

  • National Research Initiative
  • Consiglio Nazionale di Ricerche Italy
  • NY Apple Research and Development Program
  • Hatch

collaborators

  • University of Bonn
  • University of Bologna
  • HortResearch
  • Dept of Entomolgy - Geneva
  • University of Massachusetts
  • Horticulture - Ithaca
  • Hebrew University

key personnel

  • Jens Wunsche
  • Susheng Gan
  • John Palmer
  • Duane Greene
  • Terence Robinson
  • Luca Corelli
  • Eliezer Goldschmidt
  • Lailiang Cheng

department, unit, division

mission focus

From CALS annual faculty reporting. Imported on August 5, 2008