Cherries (Prunus avium)

How well established is this crop?

This crop has been grown commercially in the region for at least 50 years. Commercial returns, current growers and some level of regional based research is available to help those new to this industry.

Background

Sweet cherries originated in the area between the Black and Caspian seas of Asia. Birds probably carried seed to Europe prior to human civilisation. Cultivation probably began with the Greeks, and continued by the Romans. Contemporary cherries are genetically very similar to the initial varieties. More recent breeding programmes have produced cultivars with highly desirable characteristics, such as rain resistance, size improvement and seasonal spread.

Worldwide the plantings of cherries has increased dramatically, including New Zealand. The market is focussed on large/firm cherries. Globally 93% of cherries are grown in the Northern hemisphere, and 7% grown in the Southern hemisphere.

Cherries are grown on rootstocks to ensure even crops, and to allow the crop to be grown on different soil types and to allow for seasonal spread of the harvest. Cherries require a hot dry climate, particularly during the period 2 weeks prior to harvest, and are therefore concentrated in areas such as Central Otago, Marlborough and Hawkes Bay. More recently there has been an expansion of cherries grown under cover in bags in areas such as Oamaru.

Growers need to be aware of the risks in growing cherries, these include: frost, irrigation, birds and rain. Risk management strategies can reduce or eliminate all of the risks, but the costs of such strategies may be beyond many growers, but must remain an option to consider. Returns for crops can justify the expenditure in these remedies.

Most cherries are exported, due to the higher potential returns, however for some, local market sales may be suitable. The minimum size for export to some countries is now 26mm diameter.

Climate

Cherries are best grown in arid environments, with good winter chilling in excess of 1000 hours below 7 degress C.

Good pollination will occur during flowering where temperatures above 12C occur.

Winter Chilling and Frosts

Cherries require a period of winter chilling before they will set fruit. This is around 1000 1500 hours between 0C and 7C. The trees do not tolerate temperatures below 15C, as damage to the vascular system of the tree will occur.

Frost: Temperatures below -2C during flowering are damaging, temperatures below 0C will damage small fruit following blossom.

Rainfall and Irrigation

Little or no rain is ideal for cherries as long as irrigation is available under the tree.

In general cherries need good drainage however some of the newer rootstocks can overcome limited drainage problems. Consider the use of mounded rows to overcome water-logging, which may result from irrigation and especially frost protection using water.

Irrigation is essential in cherry growing districts. Most growers use a combination of under-tree mini-sprinklers for irrigation, and overhead sprinklers for frost protection. Use 1 mini-sprinkler between 2 trees, with overheads spaced 20m apart and 20m between rows, which is every 4th row.

Wind

Cherries prefer a sheltered environment. Shelter also reduces the stress on trees, damage to fruit, moisture loss and damage to fruitlets.

Soil

Cherries grow in a wide range of soils, but for quality growth and production a free draining soil is vital.

Fertility

Cherries require a pH between 5.5 and 7.0. Outside this range, nutrient deficiency issues can result. Soil fertility information is hard to give, because all soils vary in their status, however talk to your fertiliser representative for advice. Regular soil tests and fertiliser application is an important part of growing this crop.

Weed Control

Weed control initially and following planting is important to reduce nutrient and water use by weeds. A standard herbicide strip 1m wide either side of the row should be maintained. Once the trees increase in size, weed control becomes easier.

Varieties

The choice of variety is vital for maximum returns and meeting the importing countries quality requirements. Varietal choice also allows you to stretch the season, which is now from late November to mid February. New varieties include:
Stella mid season also used for pollination, large red flesh.
Sweetheart late season, firm, red, large.
Lapins large, firm, mid/late season red - dark.
Samba red, large, early season.
Sonnett- red, large, mid-late season, can be picked as white flesh early.
Roseann early season export cherry, firm, red.
Rainier mid season white flesh, large.
Sweet Valentine very late - February - red.
Kordia - mid season - red -firm.

Note that for export the key requirements are size and firmness.

A number of rootstocks exist for cherry production. These include mazzard, which is a vigorous stock used in replant conditions, or colt which gives a smaller tree. Dwarf stocks may become more available in the years to come, and provide easier to manage trees. Consult with your nursery supplier.

Pests and Diseases

Generally, cherries have very low pest and disease pressure. The main pests and diseases are:

Bacterial blast a serious bacterial infection of cooler districts.
Silver leaf a fungal infection that can kill the tree.
Brown rot common in wet seasons attacks the fruit.
Black cherry aphid will arrive in large populations and distort leaves and prevent shoot development.
Cherry slug a slug like insect that skeletonises leaves.
Leafroller caterpillars chews leaves and can damage fruit.
Consider the adoption of the industry export spray programme for your crop.

Layout

Plant 2 3m (2m is the most common) apart in rows 5m apart. This is the norm in Central Otago. Where possible seriously consider the use of mounded row plantings to reduce the effect of wet conditions for long periods, especially if using water for frost control.

General Management

Tree training is essential after year 1 to encourage the apical dominant (upright) trees to spread into the rows, and encourage flowering. This is a time consuming activity, but is strongly recommended early in the tree history, to establish good form, flowering and spray penetration. Grow all trees as a central leader style.

Fertiliser companies will help you with determining you fertiliser requirements and timing of application. These companies can also assist with your annual soil and leaf tests for your crop.

Bird control is essential. There is a range of techniques available, from shooting, scarers, gas guns to complete netting of the crop. Without bird control, the entire crop will be lost.

Rain protection is required, this varies from none to helicopters to complete rain covers. Cherries crack predominantly because of the water that sits in the stalk end and travels into the cherry by osmosis. The skin cannot swell enough to cope and splits. Removal of this water is therefore vital. Blowing out with helicopters, using Calcium nitrate sprays to lower the osmosis effect, can do this, or complete covers which run the water away from the canopy. No one system is foolproof however.

Harvest

Harvesting of the crop requires high labour inputs. An average picker will pick around 100kg 150kg of fruit per day. You should expect at least 10 tonnes/hectare (10000kg) from a mature crop. The issue for growers is securing picking staff and securing packing space from a packhouse. You may be well advised to contact a packhouse and discuss the issues of securing packing space for an intended cherry crop.

Equipment

If you are considering a cherry venture, you have 2 options for equipment, either purchase your own, or contract services such as spraying to a contractor or another grower. The costs of equipment establishment are high. You need to consider a 70hp tractor, sprayer, weed sprayer, mower, fertiliser spreader, hydralada, shotgun, ATV etc.

Returns

High returns can result, but equally the risks are high with this crop. For a mature crop at year 6, a conservative yield is 10 tonnes/ha. From this 60% should be export quality, 30% local market and 10% waste. Export returns of $12/kg are possible, and $4-5/kg on the local market. Net returns may be very high, but remember these may not occur every season. Costs to establish vary, but will be in the order of $50,000/ha, with no crop until year 3.

Contacts

If you are thinking of growing cherries, talk to some local growers and look at the following websites.

For fertility information www.hill-laboratories.com

Industry based grower organisation www.summerfruitnz.co.nz