An effective way to control bitter pit on apples

An orchard’s profitability relies strongly on the quality of its apples. One of the key measures of quality is fruit firmness since a firmer apple has a longer shelf life. It is generally recognized that fruits with high levels of calcium are firmer.

Conversely, when the apple’s calcium level is low, symptoms of bitter pit or senescence browning will develop. These symptoms might worsen after C.A. storage. Varieties like Delicious, Idared, Crispin, Cortland, Empire, Honeycrisp, Belmac, Melba and Primevere are particularly susceptible to bitter pit.

Foliar calcium sprays during the time of fruit enlargement help increase calcium concentrations and decrease the frequency of bitter pit. Soil application does not reduce this occurrence. Note also that an excess of nitrogen can worsen a bitter pit problem. This excess increases the size of the fruit, hence diluting the calcium.

The interaction between calcium and manganese is important. Here’s why: manganese acts as a thermostat; it regulates the absorption of potassium. The plant absorbs calcium in the form of Ca++. This cation competes with other cations like potassium (K+) to be absorbed. Research shows that when a plant has a high content of potassium, calcium sprays give weaker results than expected and sometimes no results at all. There are two ways to deal with this problem when it occurs. The first is to reduce or even eliminate potassium inputs to the crop. However, this method might not solve the problem if potassium is already abundant in the soil. A second action to take is a foliar application of manganese. Manganese regulates potassium absorption by the plant so when the concentration of manganese is right, potassium moves at a slower pace in the fruit, allowing for better calcium absorption.

Axter Agroscience has tested a 10% calcium chloride mix (AX-Ca-10). This mix also contains FulviPro, a product made of short-chain fulvic acids. The incorporation of FulviPro aims to improve both foliar absorption of the minerals and their translocation within the plant. In our trials, the amount of calcium applied with AX-Ca-10 matched that of calcium in the standard spraying program of the grower. The table below shows the trial results. In all trials, the use of AX-Ca-10 resulted in an increase of both calcium and manganese concentrations in the fruits.

These results and other trial outcomes have led us to improve the Oligo-Ca formula by integrating these new technologies. Give a try to the new Oligo-Ca 2.0 !

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