Orchard Netting: A Catch All for Climate Change Adaptation
August 22, 2016
Brendon Anthony is pursuing a Master of Science in the Horticulture program at Washington State University.
As a child in elementary school I learned that the two basic requirements for the growth and success of a plant are sunlight and water. However, as I have undergone further schooling and research, specifically in horticulture, I have learned how extremely simplified those requirements are. In reality, it takes numerous inputs and extensive management to steward the growth of a plant.
Though sunlight and water are not the full picture, they are certainly foundational. In the face of a changing climate with more extreme and unpredictable weather, they are resources that are becoming more and more challenging to preserve, utilize, and control. How to best manage sunlight and water is being investigated and tested by the Pacific Northwest tree fruit industry. This is an industry that relies on consistent temperatures both in the winter to facilitate dormancy, and during the growing season to prevent frost damage or sunburn. It is an industry that uses gallons upon gallons of water to ensure a high yield. So, how does an industry so dependent upon these crucial resources react to a rapidly changing climate, all while maintaining sustainability in their pocket books and in their surrounding environment?
Tree fruit growers across the Pacific Northwest are adapting horticultural techniques to be more resilient and endure these recent volatile seasons. One of these highly effective horticultural techniques is the use of shade netting.
The original reason growers started to cover their orchards with netting was to protect against hail. Again, extreme weather patterns brought hail at times when fruit was developing and exposed. Hail threatened the fruit’s ability to make it to the market in a consumer-friendly condition.
The desire for overhead netting grew as more recent training systems sought to increase light interception by establishing more planar, narrow, and open canopies. When the high-density plantings shifted to this style it came with the benefit of better coloration on fruit, but with the risk of sunburn damage in the event of an unusually hot day.
In the past, sunburn damage was mitigated through one of two options: either by spraying a clay-like coating over the fruit like sunblock on your kids on a sunny Inland Northwest day, or through overhead irrigation. Overhead irrigation douses the fruit with water and creates a cooling effect as that water evaporates. However, this creates a moist environment for fungus like apple scab to thrive, and it uses 25 to 40% more water.
So, how can farmers get the vibrant, delicious red coloring without risking sunburn, fungal infections, and increased water use? Netting. Netting reduces heat stress, sunburn damage, and temperatures in the orchard, all while conserving water through the elimination of overhead irrigation.
In the midst of a changing climate, protection is needed for a highly profitable and influential industry. Netting provides physical protection from intense solar radiation, excessive winds, untimely precipitation, and destructive pests and pathogens. Furthermore, netting eliminates wasteful practices and conserves water, which is becoming a more precious and valuable resource with each passing day.
Further research is now being conducted to assess what other benefits these nets can have on light manipulation, tree physiology, and fruit quality, by using colored nets that filter and select for particular light quality parameters. Some physiological effects that are being attributed to these “photoselective” nets include: increased fruit set, vegetative growth, fruit size, and coloration. All in all, these colored nets show further hope to engage in precision horticulture in the midst of an imprecise and uncertain climate.
Adaptations are needed in order to stay productive at an economically viable scale. These adaptations include, but are not limited to: new rootstocks, varieties, training systems, and netting. However, shade cloth netting provides dynamic and multi-faceted solutions to issues that surround water shortages, excessive solar radiation and gusty winds, all without having to compromise on yield. In fact, in most cases these nets provide an increase on production and quality within the orchard. The bottom line: Netting can be a wise investment for any grower looking to adapt to a changing climate.
Stamps, R.H., 2009. Use of colored shade netting in horticulture. HortScience, 44(2), pp.239-241.