Various cultivars of Navel and Valencia oranges, mandarins and mandarin hybrids are prone to fruit splitting, a pre-harvest physiological rind disorder. Gardeners often wonder if this phenomenon is caused by a nutrient deficiency. Actually, there’s another cause, but plant nutrition can play a part in the splitting of citrus peel.
How Does Citrus Peel Split?
Citrus peel splitting often occurs in periods of drought or dry spells followed by heavy rains, and is caused by environmental factors – extreme fluctuations in temperature, humidity and soil moisture. Inconsistent watering, allowing a tree to get very dry, then giving it water, can cause citrus fruit to split, and is the most common cause in home gardens.
The process by which citrus peel splits is as follows. Citrus trees are fairly shallow rooted trees, and in hot, dry weather, they’re likely to experience dry soils and moisture shortages. If the trees aren’t watered for a while and allowed to get quite dry, and are then irrigated or experience heavy rainfall, they’ll take up plenty of water, and the fruit does too, swelling up relatively quickly.
The peel of citrus fruit is fairly flexible, but In hot, dry weather, the peel becomes tougher and less elastic, so it doesn’t stretch as easily. If the fruit begins to swells from the inside very quickly, the peel will split at the weakest point, resulting in fruit splitting.
Nutrient Deficiency and Peel Splitting
When a citrus tree has deficiencies in potassium or calcium, the rind tends to be thinner or weaker, making it more prone to splitting. Providing a citrus tree with adequate potassium and calcium when fertilizing will therefore minimize the splitting of fruit.
Crop Load and Fruit Splitting
The severity of citrus fruit splitting is very much dependent on the final crop load, how much fruit the tree is carrying. The higher the crop load, the higher the percentage of split fruit. With low crop loads, very few fruit will split.
The more fruit a tree carries, the less water and nutrients it can apportion to each fruit, resulting in fruit that is smaller in size with a thinner skin. In citrus trees, the levels of potassium, which support the development of a healthy thick peel, will drop during heavy crop loads.
One way to reduce crop loads in a tree is by pruning, which has the added benefit of producing less fruit of a higher quality and larger size, rather than lots of little fruit.
Preventing Fruit Splitting
Reducing the physiological stress on a citrus tree will minimise the chances of fruit splitting, and this can be done by:
- Consistent watering, not allowing a citrus tree to get too dry.
- Correct feeding, ensuring that the tree is provided with the nutrients it requires from a balanced fertiliser which supplies all the macronutrients as well as the micronutrient required.
- Reducing crop load can through appropriate pruning.
Other articles on citrus problems and how to fix them:
- Citrus Problems – Why Citrus Fruit Drops and Flowers Fail to Develop
- Citrus Nutrient Deficiency – Yellow Leaves
- Citrus Problems – Why Is My Citrus Tree Dying?
- Citrus Nutrient Deficiency – Yellow Leaf with Green Veins
- Citrus Problems – Citrus Yellow Veins on Green Leaf in Winter
- Citrus Problems – Citrus Fruit Has Thick Peel and Hollow Core
- Citrus Problems – How to Control Citrus Gall Wasp, Methods That Work
More articles on Garden Pests, Diseases and Problems
thanks for the great explanation, and the reminders to keep moisture levels in the soil consistent. Living in FL, we usually get rain on a steady basis, but it explains those rare occasions when we have had some fruit split. And we love our orange trees!! 🙂
Valencia oranges are notorious for splitting. I never liked that fruit much anyway. I do not know why it is so popular. (Those who only want to juice oranges like their softer flesh, but they are messier to eat intact.) Mandarin oranges do not often split here. we have a pretty good climate here though. It does not get too terribly warm.
Valencia oranges are meant to be one of the best juicing oranges, they have a thin peel and are extremely juicy.
Incidentally, those are my Valencia oranges on a dwarf rootstock tree in the picture. They’ve never split, probably because I have lots of organic matter in the soil to retain moisture.
Valencias are great for orchards that produce orange juice. No one cares if the trees are somewhat sickly in appearance or if the fruit is not quite as brightly colored. Orchard trees are typically grown on standard root stock, which I think actually makes nicer trees than dwarf trees if there is enough space for them. However, the dwarf trees tend to be greener, and their fruit seems to be colored better. perhaps because they concentrate their resources better. Most of the oranges we grew were eating oranges, but those who liked Valencia REALLY liked it! Valencia was also popular with those who grew multiple orange trees of different cultivars to stretch the season out. Valencia was the first to ripen.
Down here in Australia the Washington Navel is considered one of the best eating oranges, what do you guys regard highly for eating in the US?
Ha! Washington was our main sweet orange cultivar! Robertson was second. The fruit was indistinguishable, but Robertson produced fruit in loose clusters that were easier to harvest from orchards, and Washington produced more individual fruit. It seemed to me that Robertson was more of an orchard variety that we perhaps should not have grown for home gardens. Orchard trees are on standard root stock, which we did not grow.
Nice information Plant trunk bleeding needs more explanation.
Thanks! Tree trunk bleeding is a completely different problem, I’ll have to write an article for that one, appreciate the suggestion! 🙂