Articles
FRUIT ANALYSIS
After we started in practice to advise the fruit-growers about the chances of bitter pit, some people asked why we did not use fruit analysis.
At first sight it looks more plausible to use the fruits for the prediction of bitter pit, because there must be a better correlation between bitter pit and the amounts of minerals in the fruits, as bitter pit is caused by a too low amount of Ca in the fruit or/ and a too high concentration of potash or magnesium.
For several reasons we did not do that up till now.
One of the reasons is that sampling fruits is more difficult than sampling leaves.
It is easy to take a sample of 100 or 200 leaves from stipulated places and age at random in an orchard.
For that there are standardized procedures.
For taking fruit samples, however, we first need a good prescription.
As you know there are big differences in the size of fruits on a tree, in an orchard and between orchards.
So you have to set up a research on sampling methods and the relations between the results of fruit analysis and bitter pit.
Moreover it is more difficult to handle and transport samples of fruit than samples of leaves.
An other reason is that it is taking up much time to prepare fruit samples for analysing on the mineral contents.
Moreover the analyses were more difficult in the past because the elements Ca and Mg in the fruits are on a very low level and it was not easy to find significant differences.
Nowadays with modern instruments it will be easier.
However, it is done in the Netherlands as well as in other countries, but mostly the analyses are from apples which are sampled around the normal picking time.
Those analyses can be used to find the correlation between bitter pit and the amount of some elements, such as K, Ca and Mg.
But for our purpose we need analyses from earlier picked fruits (for example in July or August) if the results have to be used for advising growers.
Up till now, I must say, we have in the Netherlands not enough results of analysis to set up a scheme for prediction bitter pit on this base.
So I could end my talk here,