How to Stop Oranges from Splitting

Fruit splitting is fairly common among citrus plants, particularity mandarin oranges. Typically, only a small percentage of fruit on affected trees will split. The exact cause is not known, but certain environmental and cultural stressors are known to contribute toward this annoying problem. Fortunately, it is not an indication of disease or pest infestation. Prevent fruit split from occurring by closely monitoring orange trees. Provide adequate fertilization and even watering, particularly if the weather is unseasonably hot during the fall season. Immediately remove or discard any split oranges from the tree and the ground. Split fruit breaks down rapidly. Decaying fruit will only attract disease, bacteria and unwanted pests. Split oranges are edible when ripe, but you will likely find that most split fruit will be green and useless.

Contributing Factors - Unseasonably warm temperatures combined with high humidity from September through November are highly associated with fruit splitting. It is believed that this sort of weather, when followed by relative dry periods, triggers splitting of some oranges. Essentially, drought-stressed orange trees start removing water from fruit to survive. If a lot of rain or irrigation follows drought, the previously removed water will return back from the roots to the fruit, but too quickly for appropriate processing. The rind of the dehydrated fruit may be unable to contain the intense water fluctuation - causing it to split.

Watering - Provide consistent irrigation during hot or windy weather to ensure that trees retain moisture in their roots. Certain orange trees, including young plants, dwarf varieties and trees planted in sandy or very porous soil, are less able to retain moisture in their roots. Consequently, these trees are especially susceptible to fruit splitting in the absence of adequate watering. Maintain consistently moist, but not soggy, soil under the orange tree canopy during hot weather.

Fertilization - Monitor fertilizer levels closely while fruit are on the tree. Depending on the cultivar, this can occur virtually any time during the year. While improper fertilization does not cause fruit splitting, low potassium levels can cause fruit peels to become thin and more prone to this phenomena. Check soil levels near orange trees for potassium if fruit splitting is observed and correct deficiencies. For best results, provide several small doses of fertilizer on a monthly basis during orange growing season.

References:
University of California Cooperative Extension Fresno County; Year-Round Gardening Questions Answered: Citrus Fruit Splitting
University of Florida IFAS Extension; Citrus Problems in the Home Landscape; Mongi Zekri, et al.; July 2010
University of California; Naval Orange Split; Pamela M. Giesel; 2001
University of California-Davis; Citrus Rind Splitting; October 2010
Why Do Lemons Split on the Tree

Are Apples Ready to be Picked?

Apples are deciduous, fruit-bearing trees, primarily grown in USDA hardiness zones 6 through 8. The most accurate way to determine whether apples are harvest-ready is to calculate number of days since pollination. Depending on cultivar, intended use and weather conditions, this varies between 135 and 180 days on average.  However, assuming you don’t know this information, there are many other indications that apples are ready to be picked. 

Time of Year – Apples ripen during the fall anywhere from early August to mid-November. Keep in mind that rainy conditions tend to delay maturation, while warm days with cool nights will speed maturation up.

Indicators - As apples mature, they grow rapidly in size and begin to produce a pleasant aroma. The base skin color of the fruit will transition from bright green to yellow. Ripe apples easily separate from the tree when lifted to a 90 degree angle and slightly twisted. Mature apples feel firm but not hard to the touch. The flesh of ripe apples is usually a creamy yellow and the seeds are black. Because apples mature on the tree they can be consumed immediately. Of course, if you are still in doubt concerning ripeness, you can always just take a bite. The flesh should taste juicy and delicious.

Postharvest –When properly stored, most apples, not including summer apples, will keep well for extended periods. Apples that ripen before Labor Day, also known as summer apples, store poorly and should be eaten within two weeks of picking. On the other hand, apples that ripen after Labor Day, called fall or winter apples, may be refrigerated for several months. Keeping fruit in plastic bags with holes helps avoid dehydration.

References:
Cornell University; Homegrown Apples in New York; Ian Merwin; October 2010
About Apple Trees: What Is an Apple Tree
University of Wisconsin Extension; Growing Apples in Wisconsin; Teryl R. Roper, et al.; 2006
Texas A&M AgriLife Extension: Apples