A proper post-harvest fertilization of apple orchards is highly important. High density orchards are likely to come under stress after the harvest, and replenishing the tree’s reserves for next season is a needed. Next season growth potential is determined by the nutritional reserves that have been built up in the buds at leaf fall.
The right application time is between fruit removal and leaf fall when leaves and roots are still active, and able to absorb the nutrients.
The most important nutrients that are needed to top-up at this period are nitrogen (N) and potassium (K). Up to 30% of the total annual application of N & K nutrient should be applied at this period.
Nitrogen and potassium are used during bloom from stored reserves from the previous year’s application. Foliar application is the most effective way to directly raise nutrient concentrations in the floral bud. As nutrients are needed in large quantities, a couple of foliar sprays are normally necessary.
In addition to the N & K macro elements, boron, zinc and magnesium are also needed to be added:
- Magnesium is needed in much larger quantities than trace elements like zinc and boron. Therefore, it is needed to split applications, of both soil and foliar applications, in the fall and spring season to avoid magnesium deficiency in the long-term.
- Zinc foliar application is more effective because zinc reacts with the soil practices became unavailable to the tree. Therefore foliar sprays must be used. Post-harvest sprays are therefore the best opportunity to get zinc into the tree.
- Boron is essential in the normal development of new tissues in shoot tips, flowers, fruit, and roots. Boron is most effectively applied immediately post-harvest by foliar application.
Suggested nutritional program
Please note that fertilization recommendation should be adjusted according to soil and leaf analysis.
| Growth stage |  |  |  |  |
| Blooming to full flowering | Petal fall to fruit set | Fruit development to harvest | Post harvest | |
| Duration | 30 days | 20 days | 70 days | 30 days |
| Foliar nutrition | ||||
| Product | Poly-Feed™ 19-19-19+1MgO+ME | Poly-Feed™ 19-19-19+1MgO+ME | Haifa Cal™ GG and/or Poly-Feed™ 12-5-40+ME | Poly-Feed™ 19-19-19+1MgO+ME |
| Application rate | 10-30 kg/ha | 10-30 kg/ha | 10-30 kg/ha | 10-30 kg/ha |
| Spray conc./volume | 0.5%-1% / 1000-3000 l/ha | 0.5%-1% / 1000-3000 l/ha | 1%-2% / 1000-4000 l/ha | 0.5%-1% / 1000-3000 l/ha |
| Application frequency | Every 14 days | Every 14 days | Every 14 days | Every 14 days |
| Nurtigation™ | ||||
| Product | Poly-Feed™ 20-20-20+ME | Poly-Feed™ 14-10-34+ME | Poly-Feed™ 14-10-34+ME | Poly-Feed™ 14-10-34+ME |
| Application rate | 5 kg/ha/da | 4 kg/ha/da | 4.5 kg/ha/da | 2 kg/ha/da |
| Total per stage | 150 kg/ha | 80 kg/ha | 315 kg/ha | 60 kg/ha |
Need more information about how to grow apples?
You can always return to the apple tree fertilizer & crop guide table of contents
