A cherry is not an apple: Effects of water - The sensitivity of these skin cells to changes in the weather is further made apparent when the cherry is exposed to water.
Maintaining cherry quality after harvest (part 3)
(Continued from last issue)
Water causes the cells of the skin to swell which makes the texture of the fruit surface stippled, resembling the surface of a basketball.
Prolonged exposure of the cherry to water causes the skin to fracture extensively. These fractures are very shallow breaks in the skin and should not be confused with cherry splitting.
When the cherry finally does split, it often occurs along the shallow fractures already present.
Cherries that have sustained excessive amounts of skin fractures become very soft and have very poor keeping quality. This may be the primary reason why rain–damaged fruit does not do well in transit, even when split cherries have been removed.
Cherries in the orchard
Small changes in the orchard can often make big differences in the ultimate quality of the cherries.
Crop size and vegetative growth should be balanced. Vegetative growth should be adequate but not excessive.
Fruit set influences crop load by determining fruit number and indirectly by the effect on fruit size at harvest.
Crop load also affects internal fruit quality.
Excessive cropping results in small fruit because ripening cherries are strong sinks for the products of photosynthesis.
This explains why excessive cropping (i.e. a low leaf-to-fruit ratio) can have a serious effect on fruit size and sugar content.
Fruit firmness and susceptibility to bruising may also be influenced by crop load.
Over-cropping will also reduce calcium in the fruit reducing firmness and increasing the likelihood of cracking.
Unfortunately, achieving a moderate and consistent cropping level is difficult and one of the greatest challenges for cherry growers.
Cherry ripening occurs concomitantly with a rapid increase in fruit size and weight during the last few weeks before harvest.
As much as 25% of final fruit weight is added on the last week of growth prior to harvesting.
During this time, dramatic changes take place in cherry skin colour, flavour, and texture. Sugar concentrations increase, while acids, principally malic acid, remain relatively constant.
Benefits of big cherries
Cherries that are sound, big and sweet stay firm, store well, are less susceptible to decay, are less sensitive to impact and compression damage and fruit shriveling.
A big cherry shaped like a sphere has a large contact between the cherry and the impact surface, which reduces the force of impacts received compared to a small cherry.
Also, a big cherry has a smaller surface-to-volume ratio than a small cherry, and a big cherry is therefore less susceptible to loss of water and bruising.
When to harvest (Continued next issue)
See this article in Tree Fruit Nov 2019