Sacramento Digs Gardening: Oranges, other fruit splitting? Weather's partly to blame

We and our gardens all enjoyed the rain last week, but folks with home orchards may have found a downside: Some or all of their not-yet-ripe navel oranges are splitting. Citrus splitting is not from disease or pests, folks with UC Agriculture and Natural Resources note. Often it involves a combination of weather and situational issues, such as stressed trees and hot, dry winds. Fluctuations in soil moisture and fertilizer also can bring it on. Oranges are the most susceptible, but mandarins and tangelos can split, too. So can that autumn non-citrus favorite, pomegranates. What happened this past week was two rainstorms (totaling about .6 of an inch in Sacramento) that followed a long dry period. If an orange tree wasn't being irrigated regularly during October, the tree reacted thirstily when the rain arrived. The moisture gets sucked up from the roots into the ripening fruit, swelling the juice cells. The rind is not able to expand fast enough to hold the extra moisture, and it cracks open. Any fruit that was sunburned during summer's extreme heat will be more susceptible to splitting. If your fruit is splitting from navel to stem, pull it off the tree and discard it. It won't ripen properly, and the exposed flesh will attract pests. Keep your fingers crossed that the rest of the oranges will be able to grow to full sweetness. Then next year: - Establish a regular irrigation and fertilization schedule for your citrus, and stick to it through fall, or until rain is a regular occurence. - Pay attention to the National Weather Service forecasts, especially in summer and early fall, and water your tree a few days before hot, windy weather is expected. After the hot spell ends, irrigate lightly, then resume the regular watering schedule. - Spread out feeding the tree through the year. Give it small monthly feedings rather than a single large application. A slow-release organic fertilizer is preferred. - Spread a good layer of mulch - at least 2 inches of compost, leaves, straw or wood chips - over the soil under the tree out to the drip line. But to prevent diseases, avoid mulching within about 6 inches of the trunk. For an excellent overview of citrus growing and care, see "Citrus Growing in Sacramento" from the Sacramento County master gardeners. Also, check out the "Celebrating Citrus" event Saturday, Nov. 9, during the Placer County master gardeners' Open Loomis Demo Garden Day, which runs from 10 a.m. to 1:30 p.m. Details are here.