26 April 1984 Growing grapes for the New Zealand market

Growing grapes in paper bags might seem the latest in prepackaging, but Lincoln College researchers hope the method will lead to cheaper table grapes for the local market and open the way to top-of the-market exports to Japan.

Lincoln College horticultural scientist Dr David Jackson and field technician Mr Nguyen Hanh both believe New Zealand has the potential for growing quality outdoor grapes.

They have selected four varieties for local conditions, and five blocks of these are presently growing in the research vineyard at the College.

A block usually has five, 10 or 20 plants, but the most promising of the varieties being evaluated will be planted in bigger blocks of about 25 plants.

Main thrust of the research at present is to improve the quality of the grapes being grown; using the bags is one way of producing more attractive fruit.

Table grapes must not only taste good, but must also look good, and growing the grapes inside a bag protects the fruit from the weather and most diseases.

The four varieties being evaluated are Pearl of Csaba, a white grape, Pirovana, a black grape, Chasselas Rose Royale and Cardinal, both pink grapes.

Pearl of Csaba ripens early, usually in February or early March, Pirovana also ripens early March, Chasselas Rose Royale in mid-March, and Cardinal, a large oval grape, in mid-late March.

Bagging grapes is not new1 the Japanese have been doing it for years, along with putting bags on growing apples and pears.

Inside the bag the grape continues growing; the bag is put around the bunch at a critical stage and left on until harvest.

An additional and more sophisticated technique is for the bunches of grapes to be dipped in the hormone gibberellin 10 to l4 days before blossoming.

This is done to induce the grapes to develop without seeds, but a second gibberellin treatment is necessary 10 to 14 days later to increase the size of the fruit.

In California naturally seedless sultana grapes are grown, but such grapes cannot be grown normally in New Zealand as the weather is never hot enough.

Dr Jackson said that by using the bags the long-term aim was to produce table grapes outdoors as good as those grown in glasshouses.

If table grapes are grown successfully in Canterbury there is the potential for filling a gap in the present market.

Nearly all grapes sold in New Zealand are imported or grown in glasshouses.

Either way, grapes never sell below $6-$7 a kilogram and are usually purchased to take to people sick in hospital.

Locally-grown grapes could sell for as low as $2 to $2.50 a kilogram, at base level, with the potential for producing top-quality grapes to sell off-season in Japan to give a return as high as $15 a kilogram.

The intention is to offer these grapes on the local market at a price that will give a good return to the grower.

Dr Jackson believes there should be no problem in growing grapes commercially in Canterbury.

"There is a good climate, and anywhere on the Canterbury Plains would be suitable so long as it is sheltered from wind, and not troubled by late frost," he said.

"There is no reason why grapes cannot be grown in any district in Canterbury, but you wouldn't want to choose a frosty area.

"Using fairly-protected areas - on some slight elevation of ground - would be wise."

Microclimates, such as on hills, could push up production costs because of difficulties of getting tractors on to the land, difficulties of picking, and difficulties of the whole operation.

New Zealand is already exporting grapes to Japan, but most are qrown in Auckland and all are grown under glass.

Grapes have been exported to Japan only for the last five or six years, but well presented fruit can give a return to the grower of about $15 a kilogram when local grapes are not available on the Japanese market.

"If by bagging and other protection we can produce similar grapes outdoors we could produce a whole range from standard grapes for the local market to high quality grapes for export." Dr Jackson said.

"Also we are hoping to get some good grape varieties from Japan ; we will be getting some of their outdoor grapes soon to see how these grow."

Dr Jackson said, Japan grew a lot of grapes and the market there wanted big grapes.

Lincoln College has been researching wine grapes since 1973, but work on table grapes did not start until two or three years later.

Only in the last two or three years have table grapes been getting major attention, and this has been because of the personal enthusiasm of Nguyen Hanh.

He is keen to see commercial outdoor table grape growing became a viable industry.

There are commercial table grape growers in New Zealand I but these grow mainly in glasshouses with some wine grape growers selecting special bunches as table grapes before harvesting.

Home gardeners in  New Zealand have been growing table grapes for years, usually Albany Surprise, a tough vigorous grape that grows well, but not recommended for commerical growers.

Dr Jackson believes the Lincoln College research will lead to people growing outdoor table grapes commercially but said these are more difficult to grow than wine grapes.

"The effort needed is much greater than for a wine grape so the grower's input is going to be higher," he said.

"Growers will be planting smaller areas, and having to put much more care and attention into their grapes."

With better growing techniques a satisfactory table grape could be grown to sell at between $2 and $3 a kilogram.

Then by improving the quality a grape between the imported or glasshouse grape and the $2.50 grape could be produced.

Ultimately, local grapes could take the greater share of the local market, but at present grapes are so dear that people do not buy them regularly.

However, if local grapes could be produced outdoors for four to five months of the year, different grades could be offered.

The harvesting technology used for wine grapes could not be used for table grapes because harvesters just bang the grapes off the vine.

Harvesters produce individual fruit, which is fine for winemaking, but table grapes have to be picked in bunches.

As Dr Jackson says, much more care is needed to produce well-presented table grapes.

Above all, he said, the College is aiming to produce a table grape outdoors as good as that produced in a glasshouse, and if this can be done "we will be producing table grapes much more cheaply."

Further information from Dr David Jackson,

Department of Horticulture, Lincoln College.