Being an irreversible process, the fruit cracker has caused great economic losses to the fruit farmers. The main reason is the growth speed of pericarp can not keep up with sarcocarp, in a word; the peel is too tight for the flesh.
There are several reasons of the cracking:
1. Drought with high temperature.
In this condition, the peel becomes brittle due to inadequate water supply( fruits will crack from the more severe part of sunburn ).And the leaf transpiration will enhance the citrus fruit water loss, increase the sugar content and cell osmotic pressure, make the fruit is in a water deficit state.
2. Brash or irrigation.
After a period of drought, a sudden heavy rain or irrigation, first plant will absorb water from roots; make the pulp expansion rapidly, resulting in peel cracking. Second, water on fruit will permeate into pericarp directly, and pulp cells change osmotic pressure to absorb water, make the pulp expansion rapidly, resulting in peel cracking. In this case, heavy irrigation and spray after drought are both wrong.
3. Pests and disease
Such as ulceration disease on orange, it cause scars on the fruit, these scars parts can not withstand the expansion of the pulp, resulting in peel cracking. Pest wounds are the same reason.
4. Improper fertigation.
After research, we found when N:Ca is over 10%, the cracking rate is 10% - 15%; when N:Ca is over 100%, the cracking rate is 100%.
The cracking is irreversible, then what should we do to precaution the cracking? In a word, keep the growth rate of peel and pulp in a dynamic balance. We have a few tips for your information.
First. Maintain the balance of moisture in soil, this can avoid fruit cracking caused by rapid water absorption.
1. For drought condition, keep irrigation in small amount. Reduce water loss and prevent ground evaporation by film mulching.
For water-logged condition, pay attention to water drain away.
And we suggest Liquid Potassium Phosphite or Liquid Calcium Phosphite With Zinc in folia spray or irrigation in both condition, because both of them can improve the plant’s immune system with plant defense against drought and water-logged soils, hot and cold temperature.
2. Loose the soil and cut roots before large amount of water supply (Brash or irrigation), it will reduce the water absorption by roots and ground evaporation. But it must be in a proper way.
Second. Nutrients supplement.
1. Potassium.
We suggest Liquid Potassium Polyphosphate for root irrigation, or Liquid Potassium Phosphite for foliar spray and irrigation, both of these products contains high amount of P and K.
2. Calcium. to enhance the intension of peel.
We suggest Seaweed Acid Calcium, contains Calcium and Seaweed Acid.
Third. Pests and Diease Control
We suggest Liquid Potassium Phosphite or Liquid Calcium Phosphite With Zinc in this condition, both of them contains Phosphorous Acid H3PO3, which has the function of anti-fungal, fungicide, antiviral,
prevents and controls plant disease. In the meantime, they can also supply nutrients.
Also, Liquid Wood Vinegar is good choice for pest control as well.