Cherries Harvesting and Yield per Hectare - Do you pick cherries with the stem on or off?

Cherries Yield per Hectare

As in other fruit trees, the yield of cherries highly depends on the variety, the age of the tree, the training system (tree architecture), the environmental conditions, and the cultivation practices (e.g., irrigation, fertilization, etc.). Generally, sour or tart cherries can produce up to 9.5 tons per hectare (3.84 tons per acre). More specifically, a sour dwarf cherry tree may produce 11.4-19 kg, while a semi-dwarf sour tree can give up to 45.4-68 kg (or 23.1-42 and 100-150 pounds, respectively). On the other hand, sweet cherries in full production capacity can give on average 4-10 tons per hectare (3272 to 8000 lbs. per acre), while some very high yields more than 14 tons per hectare (12,490 pounds or 5.67 tons per acre) have been recorded in super-intensive cherry orchards that are managed by very experienced growers. Cherry orchards with yields of more than 20 tons per hectare typically produce cherries of low quality, taste, and sugar content.

While the fruits enter the ripening stage, many farmers with dwarf and semi-dwarf varieties cover the trees with nets (permanent constructions) to protect their fruits from the birds and hail.

When and how to harvest cherries?

Which are the most important quality characteristics of cherries?

Depending on the grafted variety and the rootstock, cherry trees start producing fruits in the 3rd-5th growing year. Cherries are “summer fruits” since they are ready to be harvested during that period. The way a farmer will choose to harvest highly depends on the architecture (training) of the trees, the type-species of cherries (sweet or sour), the production purpose (fresh consumption or processing), and the availability of machinery or staffing.

Some farmers measure the sugar content of cherries with a refractometer in order to spot the ideal time of harvest. We should focus on harvesting when the fruits are fully ripe, and the skin has obtained the characteristic color of the variety. It is essential that the grower harvest the fruit at the right moment (firmness, color) depending on the demand and preference of the target market. Generally, the soluble solids content (SSC) is an important maturity indicator, and the ripe fruits should have a minimum of 14-16% SSC to be harvested. The longer the fruits remain on the trees, the higher the sugar accumulation and flavor (especially for sweet cherries, a tool that can be used is the digital refractometer (% Brix)). However, there is an increased risk of quality deterioration and yield loss (diseases-birds, the softness of the fruit, etc.).

Visual appearance is very important for consumers, and the fruits should be:

fully colored with glossy, firm skin
large in size (24, 26, 28 mm in diameter), juicy and crunchy (cherries of smaller sizes, 18-22 cm or less can be used for industrial use and processing for producing jams, juiciest, etc).
free of cracks and bird pecks
firm and not shriveled or decayed
attached to fresh green stem

It is crucial to start harvesting when the weather is dry and during the cooler hours of the day. Cooler temperatures during the night and early morning during the harvesting period are beneficial in preserving the fruit more efficiently. In areas where the Drosophila suzukii is a major problem, cherry growers harvest the fruits as soon and as fast as possible to decrease losses from the pest.

Handpicking is possible in dwarf and semi-dwarf cherry varieties and is sometimes recommended, but it needs an experienced crew in order not to injure the fruits themselves but also the spur (fruiting twig). The spur is required for future years’ production. To reduce the risk of post-harvest infections, it is essential to collect (with scissors) the cherries with the stem attached. Late maturing varieties have more uniform ripening of the fruits that can be harvested at once, while in early cherry varieties, the farmer may need to harvest in 2-3 hands (more common in plains).

The harvesting is usually done mechanically for cherries that will be directed to the process industry or/and in large commercial cherry orchards and in or charge with trees of large size (height). Growers control a harvester machine with a joystick. The mechanical harvester has a large arm that “hugs” the trunk and shakes it to cause the fruits to fall into the collecting nets. Then, they drop into a roller belt leading to a fan. The fan will help to separate the leaves from the fruit stalk. After the necessary first stage sorting (broken stems and leaves are removed), the individual fruits usually drop in a box. Therefore, they are ready to be stored.

Post-harvest management of cherries and storage

Right after harvest, it is vital to take action and reduce both the temperature and the transpiration (moisture/weight loss, fruit shrivel). For this purpose, the freshly harvested fruits should be kept in a shaded place while remaining on the farm and transported to a storage-cooling area with controlled environmental conditions. Before introducing the harvested fruits to the storage unit for more long-term storage, it is essential to apply hydrocooling to reduce the fruit temperature. More specifically, for longer storage of cherries, the temperature should be kept between -0.5 and 0.5 °C (31-33 °F), the relative humidity at 90-95% (to preserve the green color of the stems), 3 to 10% O2, and 10 to 15% CO2. Ethylene is generally not added. Except for the environmental conditions, the producer must take all preventive measures to ensure good sanitation and avoid any post-harvest contamination from pathogens or pests. The storage life of cherries also depends on the health of the fruits stored and the variety’s characteristics. For example, varieties like ‘Summit,’ ‘Newstar,’ ‘Van,’ and ‘Sonata’ are susceptible to pitting and unsuitable for long-term storage (max 15 days). On the other hand, ‘Santina,’ ‘Bing,’ ‘Rainier,’ and ‘Sweetheart’ can be stored successfully for up to 45 days.

References