Minimise rain cracking

Prepare for increased risk of rain cracking

The three-monthly outlook from the Bureau of Meteorology is for higher than average rainfall in the cherry producing regions of Australia.
The outlook period includes most of this season’s cherry crop, and if correct, growers can expect a greater risk of rain cracking.

However, the risk is dependent of when the rain falls, how long cherries stay wet, the crop load of the variety at the time, and what action a grower has taken to mitigate the risk.
It could be that rainfall during the growing season may assist growers in reducing irrigation schedules should soil moisture be at the required level, and timely rain could help grow the crop to full potential.
Varieties carrying lighter crops will obviously be at higher risk of rain damage, as will varieties that are over-cropped, as cherries will have less than ideal calcium content.
Strategies to minimise rain cracking
A number of strategies can be undertaken by a cherry grower during the growing season to reduce the risk of rain cracking.
Calcium levels
One strategy is to ensure that the calcium content in the fruit is at optimum levels.
Rain covers
Another, longer-term strategy, is to install plastic rain covers over varieties that are at most risk from rain cracking. This maybe expensive, but so too is losing a crop.
Spray-on films
When rain is forecast, there are spray-on films such as Rain Guard or Parka, and others including natural miscible oils, that may reduce cracking damage caused by rain.
Airblast sprayer
After days of drizzle or rain where cherry trees are heavy with moisture, little can be done until the weather begins to clear.
When it does clear, passing through the rows with an airblast sprayer or fan to blow most of the moisture from the leaves and fruit, can help lower the risk of cracking before sunlight hits the wet fruit.
Helicopter
Finally, for the bigger operators, the use of a helicopter to blow the rain from the trees is an ideal solution. The future may see large drones programmed to carry out a similar exercise.

See this article in Tree Fruit Oct 2020

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