Crop load management is one of the most important areas of orchard management that growers face each year. Because fruit trees often set more fruit than necessary, to ensure good size and fruit quality, fruit load is commonly reduced by thinning to reduce fruit-to-fruit competition, allow fruit enough room to grow, to expose fruit to adequate sunlight, and for better overall fruit quality. Reducing the crop load by thinning to a certain number of fruit is also important for next year’s crop. Fruit trees start making flower buds for the next season’s crop in the current growing season, therefore the crop load decisions that orchardists make will affect the current year’s production, as well as the next year’s crop. If a crop is not thinned properly, and too many fruit are left on the tree, the fruit will be small due to too much competition, the resources that would go towards next year’s buds being diminished, and producing too few return blooms the following year. If too many fruit are removed from the tree, the fruit will grow too large, which increases fruit quality and storage problems. This is also a problem during the “off-year” of alternate bearing fruit trees, when there are too few apples on the tree.
Orchardists use a variety of methods for tree fruit crop load management. The earlier that fruit thinning is done, the better to have a positive impact for carrying a larger crop, and for a good return bloom the following year. Pruning, chemical thinning and hand thinning are primary methods that growers use to achieve the desired number of fruit per tree. Chemical blossom thinners cause damage to blossoms and reduce overall fruit set. Post bloom thinners mimic plant hormones, causing physiological responses in trees, which cause fruit to drop and reduce the crop load. Reflective fabrics laid on the orchard floor reflect sunlight back up into the tree canopy and can have positive impacts on both crop load and fruit quality. New technologies to mechanically prune, blossom thin and even pollinate are being commercially used or tested today for more efficient and feasible crop load management in fruit trees. These tools were created with future labor concerns in mind. Hand thinning blossoms and fruitlets is labor intensive and expensive but is used when other methods have not removed enough fruit or more precise thinning is still required. This may particularly be the case where fruit size is important and the cultivar has a high market value, therefore justifying the added labor cost.
Precise pruning, making accurate bud and blossom cluster counts, chemical and hand thinning fruit to a desired number of fruit per tree all help to ensure the best results. Scientists at WSU and other universities are helping growers use models and decision-making tools that will enable them to make informed crop load decisions about the ideal crop loads for their specific trees, training systems, and weather conditions. Different fruit cultivars will naturally bear different sized crop loads, and this needs to be taken into consideration when making crop load management decisions. Other factors including tree stress, tree age, and temperature play a role as well. Apples, pears, and Asian pears usually require thinning. Cherries may benefit from thinning as well.
For specific information on Crop Load Management click on the accordion titles below.Factors Affecting Fruit Set Crop Load Management Techniques New Technologies
Click on the accordion titles below for additional resource links organized by crop.
- Apple Resources
- Pear Resources
- Cherry Resources
- Stone Fruit Resources