Submitted to: Good Fruit Grower
Publication Type: Popular publication
Publication Acceptance Date: 10/5/1995
Publication Date: N/A
Citation: Interpretive Summary: Recently, more attention is being given to different techniques for fertilizer timings and method of application for apple and pear trees. The results of nine apple and pear experiments in northcentral Washington indicate an advantage for fertilizing trees in November versus March as slightly higher yield was obtained with less fruit disorders. However, when trees were fertilized in late summer or early autumn, fruit disorders had a higher incidence than when fertilized in the spring. Split applications of fertilizers in autumn and spring had lower tree vigor with lower nitrogen concentrations in leaf and fruit tissues and usually a lower incidence of fruit disorders than for trees fertilized in the autumn or spring. Trees fertilized with calcium nitrate (especially in the autumn) had higher fruit quality with a lower incidence of fruit disorders in 'Red' and 'Golden Delicious' and 'Anjou' pears than trees fertilized with nitrogen fertilizers containing phosphorus and potassium.
Technical Abstract: An advantage occurred for fertilizing apple and pear orchards in November versus March because the November treatments had slightly more yield with less bitter pit for 'Red' and 'Golden Delicious' apples and less cork spot for 'Anjou' pears. Other fruit quality determinations were similar for the different fertilizer timings. However, when fertilizers were applied earlier in the autumn or late summer versus spring applications, the incidence of bitter pit or cork spot was greater for the early autumn applications. A split application of fertilizers in autumn and spring resulted in less tree vigor, shoot growth, nitrogen concentrations in leaves and fruit, and usually less bitter pit. Trees fertilized with calcium nitrate tended to have superior fruit quality with the lowest incidence of bitter pit in apples and alfalfa greening or cork spot in pears.