We are well into the apple harvest, and crop yields may exceed expectations. With some big crops this season the trees will be looking to replenish their reserves in preparation for next season.
Post harvest fertiliser
Applying post harvest fertiliser is arguably one of the most important and valuable times for tree nutrition.
After harvest orchardists have an opportunity to address any issues in the trees’ nutrient status before next season.
Post harvest fertiliser is especially important for early varieties such as Gala that have a short growing season.
A post harvest application of fertiliser is also the key time to apply fertiliser to trees that may have been restricted from getting nitrogen inputs during the season due to excessive vigour or fruit colour issues.
Due to the emphasis on fruit colour, Pink Lady™ and Fuji apples are two of the varieties that tend to receive lower inputs of nitrogen-based fertilisers during the season.
Applying fertiliser post harvest has the least impact on tree vigour compared to applying fertiliser any other time of the season.
Research have also shown that autumn applications of nitrogen give the best response for blossom quality, fruit set and early leaf expansion.
Post harvest application for next season
Post harvest fertiliser applications can have a significant beneficial impact on next seasons crop, especially for fruit trees that have been doing it tough due to environmental conditions or other factors such as heavy crop loads.
Once the fruit is harvested it’s like ‘flicking a switch’ for the tree which changes from fruit production to replenishing nutrients and carbohydrates in preparation for next seasons crop.
A new flush of root growth occurs to aid the uptake of water and nutrients.
What to consider
Things to consider when deciding on post harvest fertiliser applications include fertiliser rates, type of fertiliser, crop load, soil type and, amount of nutrients consumed by trees and incorporated into tree growth.
In general it is good practice to apply both foliar fertiliser and ground fertiliser to meet the post harvest needs of fruit trees.
Soil testing and amendments
The autumn/winter period is also a time when soil amendments can be made with gypsum or lime.
Soil testing can be carried out in established tree blocks or in preparation for new blocks.
Regular testing (about every three years) helps identify any nutritional deficiencies and underlying trends. Early detection of these trends allows management to plan the necessary course of action, before any major nutritional problems arise—ensuring the soil’s status remains in check with the trees’ requirements.
For more information, contact details and photos see the March 2012 issue of Tree Fruit