Continuity of supply is no problem.

Growing berry fruit in the off-season is highly profitable. MIKE NICHOLS looks at berry fruit production in Mexico and reports that it should be possible to produce blueberries, raspberries and blackberries in greenhouses year-round in Australasia, provided we use low chill varieties and make sure that they are grown in an evergreen manner.


In one small Mexican town, new buildings must conform with the conventional style.

While at the greenhouse meeting in Tucson, USA, I met up, by chance (we sat next to each other on the bus trip to Biosphere II) with a berry fruit grower from near Guadalajara in Mexico. By coincidence I was going to Guadalajara the following week to attend the aquaponics conference and had a spare day, so Armando Villareal offered to show me some berry fruit production in greenhouses. It was a fascinating day. I was particular interested in the out-of-season blueberry production, but the raspberries and blackberries (all for fresh export to the US market) were also very impressive.
 

Fresh raspberries are exported to the US market.

Berry fruit grower Armando Villareal.

Our first stop was at a property near Chapala, a town close to Lake Chapala. This lake is highly polluted and as it was the end of the rainy season, it was overfull. Apparently, most of Guadalajara’s water supply is sourced from the lake, a good reason for drinking only bottled water!

All the blueberries and raspberries at Chapala were covered in what can best be described as Spanish plastic tunnel houses, and these were in turn covered by bird netting to reduce bird damage to the fruit. The variety of blueberry being grown was the low chill southern high bush ‘Sharpblue’, and it was fascinating to see ripe fruit, flowers and young buds all breaking on the same plant. Continuity of supply is clearly no problem.


Berries are grown in low plastic tunnel houses.


Growers cultivate low chill blueberry varieties.



Ripe fruit, flowers and young buds all breaking on the same plant.

Raspberries were being produced on primo-canes and this was resulting in very high quality fruit. The planting material (essentially roots) was imported as a patented variety from the USA, and the first crop was produced on the tips of the primo canes. These are then cut back to about 1 metre high, and a second crop is then obtained from the growing out of the buds at the axiles of the leaves.

Because the water in the area has a high pH it is continuously dosed with sulphuric acid to give a pH of 4.5 before injecting soluble NPK fertilisers using drip irrigation. It is a necessary operation for the blueberries, but less essential for the raspberries.

Large quantities of waste plastic result from this production system. The plastic waste is collected and eventually finds its way to a recycling plant.


Plastic waste is collected and recycled.

The scenery in this part of Mexico is impressive. We visited one small town where no new building is permitted unless it conforms with the conventional style.

At Mazamitla (at an altitude of about 2000m) I was shown Mr Villareal’s high altitude blackberries and blueberries. These were not so advanced as the planting at Chapala (1500m) which was uncovered to expose them to some winter chill. The technique for producing blueberries at his altitude is to permit some dormancy, while at lower altitude the plants are treated like evergreens. The treatment of the blackberries (both thorny and thornless) was to spray the young canes with urea after fruiting, and when the leaves had fallen to prune the shoots, retaining only the more mature canes. As the buds break they are given a single spray with gibberellic acid (GA) to ensure they elongate sufficiently. As the fruits approach maturity the plastic covers are replaced on the Spanish tunnels.



Blueberries are grown at high altitude.


Young blackberry canes are sprayed with urea after fruiting.

Finally, in Tamizula I saw another lowland (1500m) crop of blueberries and blackberries. These were not covered in plastic, but only with bird netting. The blueberry variety was ‘Biloxi’, another low chill southern high bush type. Although there was some crop present Mr Villareal said that it was not worth picking - he would wait until the later fruit ripened.

So what does this mean in terms of producing out-of-season berry fruit in Australasia? I suspect that it means that it should be possible to produce blueberries in greenhouses year-round, provided we use low chill types (e.g. Biloxi or Sharpblue) and make sure that they are grown in an evergreen manner. Of course, everything is not as simple as it may seem. The berries may not harvest cleanly, where the skin is broken and the berry exudes some juice (known as ‘wet scar’). Some types retain their flowers within the fruit, but the system looks promising and is likely to be much cheaper than air freighting blueberry fruit from the northern hemisphere.

Raspberries are of course another matter. Although they are flown around the world, they ‘carry’ poorly compared to blueberries, and are much better grown locally.

Blackberries are probably a more attractive crop to grow than raspberries, because not only is the fruit larger (and therefore cheaper to harvest), but they also travel much better and their black shiny colour is a major selling point. There is considerable interest in developing a primo-cane type, which would fruit on the young cane, and then later on the mature cane, but that has yet to be developed – currently, we still have to rely on winter dormancy and cropping on old canes.

Perhaps the most important comment is that all of these berry fruit are very high in anti-oxidants and have a major role to play in our future health.

About the author
Dr Mike Nichols is a horticultural research scientist at the College of Sciences, Massey University, Palmerston North, New Zealand, and a regular contributor to PH&G.
Email: m.nichols@massey.ac.nz