Apple Production Update: Post-Frost Evaluation and Apogee or Kudos Application for Growth Control

by Amanda Green, Tree Fruit Specialist, OMAFRA

Post-Frost Evaluation

Many areas of the province hit critical temperatures over the past week for frost damage for the stage of bud development they are at. Cutting open a sample of blossoms in each block can give you a good understanding of the extent of frost damage in your orchard at this point.  This past Hort Matters article on assessing buds for frost damage gives guidance on evaluating the extent of damage. Figure 1 is a picture of a damaged bud from this year’s frost events and Figure 2 is a picture of a healthy bud.

Dissected bloom at pink showing frost damage with a brown pistol and ovary
Figure 1. A king bloom at the stage of first pink cut longitudinally. See the brown pistol and ovary indicating that the bloom is damaged.
A dissected healthy green apple bud at tight cluster.
Figure 2. A bud at tight cluster cut longitudinally revealing healthy green tissue.

Apogee or Kudos Application for Vegetative Growth Control

As buds are developing, new shoot growth is growing.  As you are checking the bloom stage, take a closer look for shoot growth as well. The best time to apply your first application is at 2.5 to 7.5 cm of new growth, it can be easy to miss this stage as shoots can grow to 7.5 cm within a few days once they start to elongate. An earlier application of 2.5-5 cm is more effective than a later time for growth control.

Repeat application(s) should be made at 14–21-day intervals, based on the level of growth control required. Apogee or Kudos 27.5 WDG requires about 14 days to slow growth and it breaks down in the trees within a few weeks. Two applications should provide good control. More treatments may be needed in locations with a long growing season, high vigour trees or trees with no fruit. Do not apply more than 4 applications per season.

See Publication 360: Guide to Fruit Protection for more information on Apogee or Kudos application.  

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