Why this choice matters 

Heatwaves above 35 °C/ 95 °F are showing up more often in traditional fruit regions, pushing fruit surface temperatures well beyond safe limits. Sunburn is no longer a rare problem: in apples, for example, repeated hot, clear days can quickly lead to severe sunburn on exposed fruit and major losses at grading. 

Across different fruit crops, a scientific review on sunburn reports that 10-30% of the crop can be downgraded or lost in hot seasons, depending on species, cultivar and climate. For export focused growers, that is the difference between a comfortable season and a year where you only break even.​ At the same time, not every protection method suits every orchard. Your goal is to build a toolbox that fits your climate, your market, your crop and most importantly your budget.​

Shade nets: strong but structural

Shade nets have become a key strategy in apple and stonefruit regions that face frequent heat and sunburn. By reducing incoming radiation, nets lower fruit and air temperature under the canopy and can also protect against hail, wind and bird damage. For high value blocks, that combination can dramatically cut severe sunburn and stabilise packout.​ However, nets are a long-term commitment. They require investment in posts, cables, and fabric, and they can change how machinery moves through the block or how you spray and prune. If you later switch varieties or need to reconfigure rows, the net structure is not easy to adapt, which is why many growers only install nets on their most profitable hectares.​ 

Kaolin and calcium carbonate: proven minerals  

Spray-on mineral films based on kaolin clay or calcium-based solutions have been used for many years to reflect light and reduce fruit surface temperature. Trials in apples show that a well-managed kaolin program can lower fruit surface temperatures by several degrees and significantly reduce visible sunburn compared with untreated trees. Calcium-based products create a similar reflective film and are widely used where nets or cooling systems are not practical.

Minerals are flexible: you can adjust dose and timing to the season and focus on the most exposed rows. The trade off is appearance. At higher rates or later applications, the white film can remain visible at harvest, and in some markets that raises concerns about colour and wash off on the packing line. Important to note that these minerals in powder form can be more difficult to mix, and the risk of clogging nozzles can be higher than with liquid formulations, depending on agitation/filtration/nozzle setup and water quality. It is worth checking with your cooperative or packer what they have seen with similar products, before committing. 

Evaporative cooling: powerful but water hungry 

Sprinklers and fogging systems cool the canopy by evaporation, using water to absorb heat from the leaves and fruit surface. In regions with abundant water and good infrastructure, these systems can sharply reduce sunburn and help maintain colour and firmness in heat sensitive cultivars. They are often used together with nets on very high value orchards.​ 

For many growers, though, water management and time are limiting factors. Evaporative cooling uses significant volumes exactly when reservoirs are under pressure, and the system needs close monitoring during each heat event. A blocked nozzle or pump failure on the hottest afternoon of the year can undo the benefit very quickly, so this method is best reserved for situations where you can guarantee supply and supervision.​ 

Bio-based reflective coatings: flexible and sustainable

A bio-based reflective coating, such as  Cropshader Orchard, is a newer option that aims to combine the flexibility of spraying with a biobased formulation and starch technology.  When applied to leaves and fruit, the coating forms a thin layer of fine white droplets that reflects excess solar radiation while still allowing stomata to function, so trees can keep photosynthesising under heat stress instead of shutting down.​​ 

Compared with mineral films, the key advantage is the formulation: Cropshader Orchard is starch-based and classified in the EU as a plant biostimulant, with a high share of raw materials of natural origin. That makes it easier to align with cooperative sustainability goals and upcoming regulatory pressure on conventional crop protection inputs. Unlike fixed structures such as nets or water hungry cooling systems, it also requires no infrastructure investment and no extra water beyond the spray volume you already work with.​​ 

Field trials in crops like walnuts have shown that treated blocks can run several degrees cooler at the leaf and fruit surface, with lower sunburn incidence and higher photosynthetic activity than untreated controls. Because the coating weathers gradually and, if needed, can be washed off on standard packing lines (depending on product and packline setup), it offers a middle road between doing nothing and risking sunburn, without requiring permanent orchard structures.  

Operationally, growers can integrate Cropshader Orchard into existing spray programs using standard equipment or drones and scale applications up or down depending on the forecast and the value of each block. That combination of biobased formulation, seasonal flexibility, and proven cooling effect is what makes starch-based coatings an attractive option to consider alongside nets, minerals and evaporative cooling, especially for export focused orchards that want both protection and a clean sustainability story.​

How to decide what fits your orchard  

Ask yourself the following questions:

• What is your tightest constraint? If capital is the main limit, building nets on every hectare is unrealistic, so flexible tools like koalin or bio-based coatings will carry more of the load. If water is scarce, evaporative cooling will always be a niche solution rather than a farm wide strategy.​​
• How strict are your market and packhouse requirements? For premium export programs, any visible film or change in colour matters. That makes it important to understand how each product looks at harvest, how easily it washes off, and what your cooperative or packer has already tested, especially if you only need early-season applications, where these products are often very suitable because the coating has more time to weather before harvest.
• How much flexibility do you need year to year? Structural solutions like nets are difficult to change, while sprays and coatings allow you to adjust rates, timing and treated area each season based on forecasted heatwaves, canopy size and expected prices.​​ 
• What proof can you see in crops like yours? Before committing, ask every supplier whether for nets, coatings or cooling systems, to show data from orchards with comparable crops and climates. Useful information includes fruit and leaf temperature curves, sunburn percentages at harvest, and any yield or packout differences.

If you want to see how a bio-based coating performed in various orchards during extreme 2025 heatwaves, including temperature benchmarks, sunburn levels and photosynthetic measurements, use the whitepaper as your next step. It gives you a concrete reference when you compare different heat protection options and decide what will keep your own fruit protected and insured while making the best use of your budget and resources.

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