SA apples: all set for healthy growth

By embracing new technology to ensure a greater yield and utilising resources efficiently, South African apple producers can look forward to a bright future.

Some of the main research areas for future apple production practices in South Africa include new rootstocks, higher planting densities and the possibilities for mechanisation. Photo: Denene Erasmus

The world’s population, growing by more than 200 000 people a day, will increase to nine billion by 2050. More than 50% of people now live in cities, compared with just 5% at the turn of the 20th century. These factors, combined with climate change and declining natural resources, are reshaping the world we live in.

One of the greatest emerging challenges is a threat to global food security. To adequately feed the world’s growing population, food production must double by 2050. And to achieve this, farmers will have to produce more with fewer resources. This was one of the main topics discussed at the recent Hortgro Science Technical Symposium 2014, where several researchers and specialists looked at how pome fruit production practices could be adapted to meet ever-growing consumer demand.

Holistic managemen

Dr Mias Pretorius, technical manager for the Two-a-Day Group, and one of the presenters, said the apple and pear industry needed to embrace a holistic, sustainable farming approach that included not only new production practices but social and political aspects.

“We have to continue to invest in increasing our yield. The productivity of our workforces needs to increase. As an industry, we also have to pay serious attention to transformation, and the upliftment of rural communities.” 

According to Pretorius, the industry needed a stable political environment to move forward and therefore it was in the industry’s best interest to join forces with government, offering assistance in transformation and job creation.

Labour and mechanisation

Farmers had little control over many of the challenges faced by the industry. For example, the effects of climate change would most likely have a far-reaching impact on the environment in which they farmed. But, Pretorius said, some things could be controlled through better management. Better worker training, for example, would yield fast, tangible results.

According to Pretorius, the Two-a-Day Group incurred about R60 million a year in losses due to bruising and injury to fruit during the picking process. A rough estimate suggested that losses for the entire industry could be as high as R600 million a year. “Just by providing better training for pickers we can make a huge difference here,” he said.

Charl Stander, technical manager for quality and advice services at Franschhoek Fruit Packers, said that training of labour needed to include higher level training to familiarise workers with new technology. As more farmers looked at including some form of mechanisation on their farms, higher skilled labour was needed to operate the new machines, he explained.

In the future, trees would probably be planted in narrower rows and would be trained and pruned to be shorter for greater ease of picking. Alternatively, orchards might be planted according to specifications that would allow farmers to make use of picking platforms.

Farmers are advised to select an irrigation system according to the conditions in which they farm. This will determine the water needs of trees.

But for the foreseeable future, said Stander, manual labour would still be required for harvesting. “For full mechanical harvesting, you’ll need a very complex system that will not bruise the fruit, and such a system has not been developed yet. That’s why it will remain crucial to improve worker productivity and efficiency through more training,” he said.

Orchard manipulations

Pretorius is part of the team that heads up the Orchards of the Future programme initiated by Hortgro Science to create a platform for technical teams and researchers to test innovative ideas in the South African apple industry.

Some of the trials being conducted by the group include monitoring the effect of netting on apple production, evaluating the performance of new rootstocks, and assessing the potential of higher planting densities.

Another presenter at the symposium, soil scientist Nelius Kapp of annual seed industry journal Prophyta, predicted that future apple orchards would have a density as high as 2 000 trees/ha to 2 500 trees/ ha, planted on high fertility rootstock. Moreover, training and pruning techniques would allow greater mechanisation and better labour productivity.

He said that for high- density plantings, soil preparations should include the following:

• Ridging to create uniform soil depth and prevent waterlogging by enabling the root zone to dry off quicker during wet seasons.
• Mulching – Kapp suggested using hay during the first year after planting, wood chips on young trees and that from the second year, annual weeds should be allowed to grow.
• Subsurface drainage for areas prone to water logging.
• A soil moisture monitoring system.
• Soil fumigation. Kapp pointed out that poor soil water status management could be the primary limiting factor in apple production. 

“The soil moisture status has to be monitored continually to ensure that the tree has access to enough water and to prevent waterlogging in the root zone,” he said. If this were not properly managed, waterlogged soil would encourage the development of soil-borne diseases which could affect root function. Roots affected by disease would in turn influence production.

Turning to netting, Kapp said its use in orchards could prove a problem for flower and fruit set. It was therefore only viable as a risk management measure in areas that experienced frequent hailstorms. He was more positive about the future of netting use by apple farmers, saying that in some trials certain apple varieties had proved to be 10% to 20% more productive when grown under netting.

“I think netting will be part of our future but more research is needed to determine the best colour and structure for netting,” he said.

Pests and diseases

Two related threats to the pome fruit industry are the occurrence of new pests and diseases, and the difficulty of controlling these due to pesticide and fungicide resistance. Speaking at the symposium, Bekker Wessels, a private pest and disease management consultant, said that Bactrocera invadens (invasive fruit fly) was currently of particular concern to the fruit industry.

“It’s a threat already present in the Northern parts of the country, that has the potential to greatly damage the apple and pear industry. But there are research programmes running aimed at developing management programmes that will effectively manage this pest and allow for the continued export of fruits,” he said.

According to Wessels, pesticide and fungicide resistance was an expected consequence of pesticide use. “Several of the so-called easy chemistry options used in our industry have been depleted. To counter this threat, the development of non-chemical control methods should be seen as a priority. Farmers must also make more use of the non-chemical control methods already available.”

Controlling reproduction

Two of these, he explained, were the mating disruption technique and the sterile insect technique (SIT). Both were aimed at decreasing pest populations. SIT, which is used in South Africa for the control of Mediterranean fruit fly (Medfly) involves the mass rearing of fruit flies, the sterilisation of male insects using gamma radiation, and the release of sterile male fruit flies into orchards and infested areas. The sterile males mate with females in the wild and the eggs laid are then infertile.

SIT is used by farmers in parts of the Western Cape as part of an area-wide Medfly control programme which uses a combination of control methods. This approach integrates different control strategies, including chemical and non-chemical control, and is known to delay the onset of pesticide resistance. “It’s the only sensible way to manage this problem over the longer term,” said Wessels.

As global pressure for the reduction and even elimination of pesticide use increased, the potential for bio-control agents would need to be emphasised, he stressed. The local industry had invested in research of entomopathogenic nematodes (a group of nematodes that parasitise insects) and initial results looked promising. Local research was also due to start in the coming season on entomopathogenic fungi, which also prey on insects.

Wessels also pointed out the benefits of mulching for pest control. “Not only do we see better performance in young trees, especially, but in mulched soil we’ve seen an increase in biological control of pests, like woolly apple aphids,” he said. However the benefits of mulching sometimes came with risk. He said that research was about to be carried out on the risk of spreading ‘stem cancer fungi’ through using wood chips from fruit trees as mulch.

Climate change – the wild card

“Global warming is the ultimate game changer, as even small increases in the average temperature will have very significant effects on pest and disease populations. In addition to this, associated changes in climate such as rainfall patters will affect ecosystems,” said Wessels.

He added that it was difficult to predict exactly what the effects would be because of the multiple factors involved. Some species were expected to be favoured by increasing temperatures while others would suffer. The woolly apple aphid, for example, would most likely be negatively influenced by increasing temperatures. However, its natural enemy, Aphelinus mali (an endoparasitoid of woolly apple aphid), would probably benefit, leading to a potential increase in bio-control of woolly apple aphid.

“On the other hand, higher temperatures may impose greater stress on fruit trees which might increase their susceptibility to mite pests,” said Wessels.

Choosing new varieties

New apple and pear varieties are constantly being developed in response to changing consumer demand and the needs of farmers for better performing fruit. According to Pretorius, there was no one-size-fits-all solution when choosing new varieties. “Farmers have to determine though trial and market research what will work in each specific area and farming operation. The rule is to match a variety to your farming conditions, not the other way around,” he said.

Pretorius added that when selecting new varieties, the focus should be on optimising labour productivity and spreading risk by choosing varieties with different ripening times to extend the picking season. “The apple and pear industry has changed a lot in last 10 years. I believe we’ll see even more changes in the next five years,” he said.

He cautioned, however, that while it was important to find new, more effective ways of farming, correct implementation of the best management practices such as integrated pest control, better irrigation management and worker training, would have a much larger impact on yield in the short term than innovations that still needed testing.