Evaluating the influence of drape netting on spray deposition and disease control in apple orchards using apple scab as an model pathogen

Investigating the influence of drape netting on spray deposition parameters and the resulting influence of drape netting on pest and disease control using apple scab incidence in drape netted orchards as a model pathogen. This data can help growers decide if a high disease incidence risk orchard can or cannot be draped possibly.

Spray deposition parameters were evaluated on apple leaves sampled from draped and undraped trees in two separate apple orchards sprayed with a fluorescent dye through fluorometry, macrophotography and digital image analyses. Apple scab incidence and severity was evaluated on fruit following a season of fungicide spray applications on draped and non draped trees at harvest.

Spray deposition realised on drape netted trees was lower than that of undraped trees, in some cases significantly.

Progressive spray application methodology realised better deposition parameters, especially quality and quantity, on draped and undraped trees in relation to conventional spray application methodology.

Drape netted trees realised higher percent apple scab lesioned fruit than on undraped trees, however not significantly.

Early season primary apple scab infection prevention before draping realised no scab infection on draped trees at harvest.

This work concluded that draping of apple trees reduces spray application deposition parameters. Spray application on drape netted trees can be improved by using progressive spray application methodologies. The study indicates the importance of early season apple scab prevention and control before trees are draped in November, where draped trees can potentially increase scab fruit at harvest due to poorer spray deposition and more conducive environment. Whether this data can be used as a decision making tool if an orchard needs to be draped or not needs to be weighed against the possible positives of draping an orchard for example reducing sun-burn damage, excluding codling moth and reducing the chance for hail damage.

Drape netting reduces spray deposition parameters. Deposition parameters can be improved on drape netted orchards using progressive spray application methodology.