How vulnerable is a monoculture of shrub willow to pests and diseases?
Although willow crops regularly produce high yields without the use of any pesticides, some pests and diseases can damage shrub willow plantings, reducing yield and making the plants more susceptible to other biotic and abiotic stresses. Most pests and diseases are moved by wind, rain, or animals from one shrub to another, but most pests and diseases are also very specific as to which host species they will feed upon or infect. Growing shrub willow in a monoculture, where only one variety or many closely related varieties within a species, are grown together, can provide a habitat conducive to major outbreaks of pests and diseases since the pathogens can easily move from one shrub to the next. Planting polyculture plantations, with many different genotypes, produces natural barriers to that movement, reducing the spread and ultimately reducing the damage pests and diseases can do in shrub willow plantations.
