Research to Support Apple Orchards
September marks the beginning of fall and apple harvest season for local orchards. When you think of apples you may not immediately think of the Central Midwest, let alone Kansas. But despite obstacles (e.g. extreme weather, pests/disease, and farm consolidation)commercial orchards have been active in the Sunflower State for more than 150 years. Check out K-States Growing an Orchard report from 1950 for more historical context: https://www.ksre.k-state.edu/historicpublications/pubs/SB337.pdfAnd over the last recent decades, commercial orchards across the globe and regionally have shifted away from the characteristic grove-style planting with large freestanding trees that could be spaced anywhere from 10-20 ft apart with 100+ trees/acre. Orchards today are moving to a high-density system that uses dwarfing rootstocks to grow smaller trees, spaced 2-4 ft apart, pruned to a spindle shape and supported by trellis squeezing over 1,000+ trees/acre. These high-density orchards require a significant upfront investment to establish but they can facilitate the efficiency of orchard maintenance and labor, produce larger yields per acre, and generate a much higher return on investment. 
And over the last recent decades, commercial orchards across the globe and regionally have shifted away from the characteristic grove-style planting with large freestanding trees that could be spaced anywhere from 10-20 ft apart with 100+ trees/acre. Orchards today are moving to a high-density system that uses dwarfing rootstocks to grow smaller trees, spaced 2-4 ft apart, pruned to a spindle shape and supported by trellis squeezing over 1,000+ trees/acre. These high-density orchards require a significant upfront investment to establish but they can facilitate efficiency of orchard maintenance and labor, produce larger yields per acre, and generate much higher return on investment.
Sunburn caused by high heat and light intensity is a leading cause of apple cullage in the Midwestern climate. This environmental damage can be exacerbated in local high density systems which provide less natural shading to fruit due to the limited foliage on spindle-type trees.
In 2019 Johnson County Extension received grant funding from Kansas Department of Agriculture to conduct on-farm trials at two orchard in North East Kansas (Gieringer’s Family Orchard & Berry Farm in Edgerton, KS and South Baldwin Farms in Baldwin City Kansas). This research and education project was initiated in the 2020 growing season to assess the feasibility of protective drape netting for sunburn protection and improved fruit quality for local high-density apple production.
Drape Net is product developed originally for the fruit industry in Australia, and it’s exactly what it sounds like, large woven mesh that can be draped over the tops of fruit trees and trellises providing protection from hail, birds, pests and sun damage. Typically the use of these protective nets is not practical at scale. The time and labor cost required to lift and cover one tree, let alone one acre, prohibit the feasibility of these nets for commercial growers in Kansas. Hydraulic mast applicators can increase the efficiency of this practice but this machinery is expensive for small growers.
Wettable powder sprays, like kaolin clay, are a viable alternative which shade fruit with a chalk like coating; however, these sprays have to be reapplied depending on weather and can require multiple application during the growing season—which is highly resource intensive (e.g. labor, water, machinery and fuel).
Previous trials have shown that despite the added protection provided by netting or sprays, shading can lead to slight reductions in fruit reddening and maturation. Red color in certain apple varieties, like the ‘Honeycrisp’ variety in our trial, can be very difficult to achieve because those pigments require cooler summer temperature for optimum development.
Johnson County Extension was able to use KDA grant funds to purchase a specialized hydraulic net applicator and drape netting for on-farm research of this system which had not been studied in Kansas orchards previously.
Trial comparisons included Drape Net, spray protectants (i.e. kaolin clay), control groups (uncovered) and use of reflective ground covers to counter color reduction potentially caused by protective treatments.
Harvest was recently completed at South Baldwin Farm, followed by quality testing in the Post harvest Physiology Lab at K-State Olathe to evaluate fruit samples from the different treatments based on color, firmness, sugars, acidity, and starch. Results from on-farm trials will be disseminated through a mix of publications, field days, online videos and extension presentations—so stay tuned!
