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Friday, October 27, 2017

Pomegranate Fruit Splitting Usually Water Problem

Q. I have grown Utah Sweet pomegranates in Summerlin for several years and only had a few fruit split open near the Fall harvest time. Mid July this year 40 green fruits split open. I assumed it was from high temperatures but more kept splitting open through the rest of the year. At least 80% of the fruit have split open and the birds cleaned out all the edible seeds. 
Split Utah Sweet pomegranates do to watering problems.

A. Harvest times for pomegranates are at different times depending on the variety of pomegranate. The earliest varieties start ripening in September and other varieties extend the harvest season past Halloween.
            The usual reason for early fruit splitting is irregular applications of water: soils alternating between wet and dry. Pomegranates handle high temperatures easily but they don’t produce well if water in the soil is limited during its fruiting cycle. 
Split Utah Sweet pomegranates most likely from irregular soil moisture. This can be a particular problem when trees are on drip irrigation and surrounded by dry soil. Don't turn off the irrigation system when it rains when growing in the desert. The amount of water the plant received is hard to calculate.
            Fruit splitting is a watering issue, not a temperature issue but the two could be related. If water is not available when the fruit is increasing in size, even for a day or two, fruit will be smaller because they begin maturing too early. Their outer “skin” begins to harden early.
            Now it rains heavily. This abundance of water available to the roots is “pushed into the fruit causing the fruit to expand and split. Unusually high temperature, combined with wind and an unprotected soil surface, can cause drought at times that are unexpected. Irrigation water is supplied according to a clock but it is too late. The damage is done.
            Put a surface layer of mulch 3 to 4 inches deep on top of the soil to slow water evaporation from the soil surrounding the roots. This surface layer of mulch helps to reduce wildly fluctuating amounts of water in the soil when it is hot and windy.
Pomegranate before winter pruning and surrounded by wood chip mulch in the desert
            Use woodchips from trees pruned by local arborists. Extend this surface layer of mulch so that it completely covers the soil under the tree canopy to a depth of four inches. Make sure these trees receive enough by adding emitters as it gets bigger and checking the soil moisture during hot weather.
Round hole in the side of pomegranate with inside totally cleaned out is a pretty good indicator of a rat problem.
            Birds eat pomegranate seed after the fruit has split open. They can’t open pomegranate fruit by themselves. Rats gnaw on the outer “rind” of the fruit leaving a large, somewhat round gaping hole in the side of the fruit with the inside totally cleaned out. One of the pictures you sent to me looks more like rat feeding than bird damage.
            Because rain in the desert happens so infrequently, never use the rain shut off on the controller. Irrigate plants even though it rained because estimating the amount of rain plants receive is very difficult to do accurately.

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