Inadequate shelter is costing kiwifruit growers tens of thousands of dollars a year in lost production, says Mr Rick Reid, marketing director of Savlon Reid Ltd.
Research indicates that about 80% of all kiwifruit orchards have inadequate shelter he says, and this could be costing some orchardists up to $50,000 a year.
Mr Reid believes poor shelter in many cases is the result of poor planning based on the old formula that a shelter belt gives protection over a distance eight times its height. Using this formula the fences appear to act as a series of independent windbreaks with wind velocities often accelerating to the original speed before the next fence.
Mr Reid said, in fact, the shelter provided often less than five times the height, and in some cases windshelters are actually increasing the velocity of wind in the orchard.
Research carried out at a production block by the University of Auckland in collaboration for Sarlon Reid, showed the wind velocities were greater on the lee side of the shelter than on the windward side, and that only a small proportion of the block was being protected.
Mr Reid said often the necessary improvements are inexpensive when related to the likely improvement in yields, which he estimates, should pay for itself within the first year.
“The first priority in improving shelter is to find out what is happening to the wind up where it matters — above the structures.
“The critical height is from 1.8 metres to 3.3 metres, (6-11ft) where future years’ canes will be.”
“Mr Reid said flags put up at the critical heights in grid formation — will indicate what the wind is doing, and he said some orchardists would be surprised to see just which direction the wind is coming from.
“The same applies to the development of bare land. Developers must know the real direction of prevailing wind, and often it will not be the direction they think.
The main aim is to get wind up and over the orchard and not down on the vine canopy. Mr Reid said the best way to achieve that is by using shelter cloth.
“Most living shelters are too dense and send the wind bouncing off and into the orchard in all directions creating strong eddy flows and turbulence and also increasing frost tendency. “Shelter must be permeable so the wind can filter through it,” he said.
Mr Reid often recommends the addition of overruns of shelter cloth above existing kiwifruit rows to keep the wind out of the orchard but he stresses that every block must be considered separately.
Artificial shelter does not have to run north-south to minimise shading, but can be installed in any direction.
Wind protection is an important prime factor in gaining high production levels in the minimum time, he said, and the important relationship between adequate shelter and production is confirmed by horticultural advisory officer, Peter Lyford of the advisory services division of MAF.
Mr Lyford said lack of shelter is one of the major factors limiting orchard performance and is a problem that is best avoided in the beginning.
“Even the worst sites can be improved by reducing the problem,” he said, “and my observations suggest that their average orchard development has a huge potential to improve crop yields by lifting the standard of orchard practice in several areas including shelter planning.
“Shelter planning and management, along with vine management accounts for most of the difference between average and top performance,” he said.
According to a Ministry bulletin wind is the most limiting factor in establishing an orchard since subtropical fruits such as kiwifruit have a greater requirement for shelter than most other horticultural crops.
Besides providing physical protection for high-value crops, proper shelter creates a warm micro-climate essential for crop establishment and fruit quality, and without proper shelter kiwifruit and avocadoes simply will not provide export quality fruit.
Mr Lyford said there are two options available to increase orchard profitability — minimising costs or increasing revenue through better crop performance.
“The potential to improve income by cost saving is very small compared to the opportunity of increasing revenue by maximising crop performance,” he said.
“I believe attention to technical management is the key to successful fruitgrowing.”
Sarlon Reid has developed a new wind reducing cloth which the company said will have a longer life than other shelter cloths. It is also developing new lighter supports for the cloth.
From Growing Today, September 1983