Apples With Water Core Are Safe, Even Sweeter

Q: I have a wonderful old King apple tree that bears well every year, but this year the apples were bizarre. In September they started looking like they were frosted with an almost transparent appearance to the flesh. They also have some spots.

A: A physiological condition, called water core, is probably happening in your apples. It is not a disease, but instead occurs when the ratio of nitrogen to calcium is too high. The transparent appearance results from a retention of water and one of the fruit sugars around the core or throughout the flesh of the apple.

Apples with water core are quite safe to eat, and will be sweeter than apples of the same variety without this condition. In Japan, these apples are preferred and highly prized. Some commercial growers in Washington are producing apples with water core to cater to the desire for these sweeter apples. A slight amount of water core will have little effect on storage, but more severely affected fruit will tend to become brown over time.

To prevent water core, reduce, but don't eliminate, the amount of nitrogen fertilizer to your tree. This will help to bring the nitrogen and calcium into a better balance. It's also important to harvest your apples as soon as they mature to reduce the accumulation of excess sugar.

Some varieties of apples mature much later than others, so keep an eye on your tree until you can predict about when yours are ready to eat. Harvest as soon as the apples with their stem break easily from the tree and they taste ripe. You may also want to just enjoy an exotic, extra-sweet apple treat!

Q: I'm worried about our enormous horse chestnut that has brown lines around the perimeter of the leaves. We give it good care, but this doesn't look normal.

A: Horse chestnuts are spectacular trees with a beautiful spring show of creamy white flower candles. The leaves are large and subdivided into leaflets so that the appearance is like a big fan. The large shiny seeds are poisonous to humans, but squirrels collect masses of them for food.

The trees grow well in our climate, but even large, mature trees do need supplemental water in the summer, especially during droughty years. A very typical symptom of water stress is the brown rim around the outside of the leaves. It's hard to remember now that rain is rare during our summer months, but many plants will need supplemental watering in the dry season.

Horse chestnuts will often have yellowed leaves in the summer and prematurely drop their leaves as early as July if the lack of water is extreme. The trees are able to survive unless drought conditions and lack of supplemental water persist over a number of years. Stressed trees become more susceptible to attack by diseases and insects. Proper plant care is one of the best pest control methods!

Gardening runs Friday in Scene and Sunday in Home/Real Estate. It is prepared by Mary Robson, Master Gardener program director, Holly Kennell, Washington State University/King County Cooperative Extension agent, Susan Miller, integrated pest management specialist, and volunteer Master Gardeners.