It is important that potassium concentrations are in balance with other cations, particularly calcium, as preferential uptake of potassium over calcium will significantly increase the risk of rotten fruit and physiological disorders.
Minimizing Incidence of Apple Rots and Diseases
Many disease-causing pathogens (fungi, bacteria, viruses and nematodes) attack apple trees. These may damage the fruit directly, making it unattractive or inedible, but also weaken the apple tree by injuring or invading the leaves, trunk and branches. Damage to apple trees reduces productivity and increases susceptibility to winter injury or attack by additional pests.
The most common diseases are rust, scab, different rots and fire blight. Attacks from a variety of insects and mites are frequent too. Good crop nutrition is essential to promote the health of apple plants and make them more resistant to pests.
Crop Nutrition and Apple Rots and Diseases
Potassium
Storage rots including Gloeosporium rot and penicillium can be minimized by use of calcium. Repeated foliar applications are the most effective at alleviating this kind of damage.
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Increasing Apple Firmness
Over-use or late applications of nitrogen reduces apple firmness, potentially resulting in more damage in transit and storage, and a reduced shelf life.
Reducing Bitter Pit Incidence in Apples
Bitter pit is a physiological disorder associated with low levels of calcium in the apple tissue, which reduces apple quality and marketability.
