Schlies Orchard Report 2006
By Tami Schlies
This was a good year for fruit yield at our house. Almost every apple tree produced fruit, and the Evan’s cherries actually produced enough for a couple of pies (well, would have if my son had not had a feast one day while he was looking for duck eggs in the orchard.) The Opal plums and Dan’s Yellow produced their first plums and were quite delicious. A handful of honeyberries and gooseberries, buckets of strawberries, and enough currants for a few jars of jelly round out my fruit larder for the year. The kiwi sulked after finally being planted in the ground this year, but will hopefully spring back next year – they were producing fruit while in the pots.
I noticed when eating green fruit from my Norland tree earlier in August (yes, I am an avid green apple muncher. I like ‘em sour.) that while the fruit was juicy and good, it had a brown layer inside, as if it had oxidized. This tended to be more prevalent in fruit on the southwest side of the tree. After doing some research, I believe it is brown heart. Brown heart is believed to be associated with cool, wet weather and high nitrogen fertilizer and is caused by high levels of CO2 in the fruit. My orchard is in the poultry yard, thereby getting plenty of nitrogen. I also fertilized with bone meal and greensand this spring; the nitrogen content of the bone meal (6-12-0) may have been too much. The older the fruit got, the more apples were affected by the browning.
Brown heart can also be more severe in fruit when watercore is also present, as the accumulated fluids prevent adequate gas diffusion in the tissues, so it is not surprising that later in the fall I noticed my large Norlands exhibiting glassy, water soaked looking flesh at the basal end; a classic watercore apple. Experts believe that late in the season if conditions are right (low night-time temperatures and plenty of rainfall), sap is delivered to the fruit cells too quickly for them to absorb, resulting in the intravascular cell spaces filling with fluid. High light intensity and temperatures exacerbate watercore symptoms, explaining the higher concentration of affected apples on the southwest side of my tree. Larger fruit also tend to develop watercore more than smaller fruit.
Calcium plays an important role in both brown heart and watercore. I added Quickcal earlier this spring, but obviously not enough. I also foliar sprayed with a weak solution of boron, but the publication from UC Davis on Postharvest Technology states that high fruit boron may also contribute to watercore. I intend to have the soil in my orchard tested this fall to verify how much calcium and boron is actually available to the trees.
Although watercore is unattractive, it does not lower fruit quality or flavor of apples if they are used before the accumulated sugars begin to ferment. Next fall, taking sample harvests from the southwest quadrant of the tree early on and checking for browning or watercore will be a good indicator of when I should harvest to minimize watercore damage.