|ISHS Acta Horticulturae 1020: VI International Cherry Symposium
GROWING SWEET CHERRIES UNDER PLASTIC COVERS AND TUNNELS: PHYSIOLOGICAL ASPECTS AND PRACTICAL CONSIDERATIONS
|Author: ||G.A. Lang|
|Keywords: ||Prunus avium, protected environment, fruit cracking, frost protection, fruit quality, high density orchard, production efficiency, dwarfing rootstocks|
Other than growing sweet cherries in environments with minimal rainfall during ripening, the next best method to avoid rain-induced fruit cracking is to exclude rainfall from contact with the fruit by protecting trees with plastic covers.
Numerous covering systems have been engineered over the years, from pole-and-wire “tents” to steel hoophouses or “high tunnels”. Although rain exclusion is the common trait, often there are additional unique benefits and limitations to each system, including not only practical management issues but also significant impacts on cropping physiology and insect/disease management.
Five years of research on cherry produc-tion in high tunnels has highlighted how the seemingly simple modification of the orchard environment by plastic covers can reduce wind speed, increase air temperatures and consequently growing degree units, and reduce the incidence of some diseases while increasing the potential for others.
The reduction in transmitted light can impact not only photosynthesis, but depending on specific spectral variations, can influence the activity of pollinators and other insects, tree architectural development, and fruit color and bioactive compound biosynthesis.
Furthermore, simply excluding direct contact of rainfall with fruit does not necessarily guarantee an absence of cracked fruit! Overall, yields and fruit quality in high tunnel production have been outstanding, though each season has brought new challenges to resolve.
We are nearing the optimization of high tunnel cherry production systems that incorporate and synthesize multiple technologies, including dwarfing rootstocks, fruiting wall architectures, reflective orchard floor materials, high frequency/low volume fertigation, and overhead canopy spray delivery systems.
The scheduling of sequential covering dates, to broaden the periods for bloom and ripening, is best optimized by tracking growing degree unit accumulations rather than by using calendar dates.
The various potential impacts of intensive high tunnel production systems are discussed relative to less extensive covering systems, such as pole-and-wire tents.
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