Disposing of fruit waste affected by spotted wing drosophila

Fruit affected by spotted wing drosophila (SWD) is unmarketable and must be disposed of as waste during and after the harvest operation. Inadequate disposal perpetuates populations of SWD in soft and stone fruit crops. Discover best practice in disposing of this fruit waste.

This information was last updated in 2016.

Action points

• All waste fruit should be removed from soft and stone fruit crops both during and after harvest to reduce the risk of SWD damage.
• Waste fruit should be disposed of in sealed plastic pallet bins with a capacity of between 500 and 670 litres.
• A combination of depleted O₂ and high CO₂ concentration is needed to kill SWD in the waste.
• Treatment of soft fruit waste in sealed bins for two days at waste temperatures of at least 18°C will ensure eradication of SWD. If waste temperatures are below 18°C, three days are required.
• There can be a low level of survival of SWD (5% of the original population) in stone fruit waste treated for three days, particularly if the waste temperature is below 16°C.
• A four-day treatment should be used for stone fruit.
• Rotavation of treated waste into soil to a depth of 20cm is a suitable disposal route. The rate of application of treated waste to land should not exceed 125 tonnes/ha.
• Mixing the treated waste with at least 90% weight for weight (w/w) with other organic waste is a suitable disposal route.
• The availability and gate-fee cost of large-scale composting and anaerobic digestion facilities in the vicinity should be explored as an alternative disposal method.

Figure 1. Fruit waste left on the orchard floor can attract adult SWD.

The importance of disposing of fruit waste

If managed incorrectly, spotted wing drosophila (SWD) can lead to crop losses and fruit waste in soft and stone fruit crops. SWD is attracted to underripe, ripe and overripe fruits, so it is vitally important to remove any damaged, diseased and overripe fruits which were often traditionally left in the field, as they are still attractive to SWD. It is also essential to remove old and waste fruit which may have fallen to the ground, to prevent further SWD population build up in a plantation (see Figure 1).

The form of disposal is crucial however. Discarding any reject or waste fruit on open heaps must be avoided, as this allows SWD to reproduce, feed and over-winter (females in reproductive diapause). Rapid composting would be ideal but the sufficiently high temperatures required to kill SWD can be difficult to achieve in fruit due to its very high moisture content. Freezing of waste can be an effective alternative to kill SWD but it is often impractical to dispose of large quantities of frozen waste.

One practical solution is to utilise the oxygen demand and carbon dioxide produced by fermenting fruit waste in sealed bins to kill SWD, similar to the techniques used for controlling insect pests in store.

Collection and treatment of spotted wing drosophila fruit waste

The swift and consistent collection and treatment of fruit affected by SWD is vital to curtail its spread. Discover best practice for collection and treatment of spotted wing drosophila fruit waste.

Disposal of spotted wing drosophila fruit waste

Even treated fruit waste remains attractive to egg-laying SWD, making disposal a hugely important final action to combat the fly's re-emergence. Find out about the options available for disposal of spotted wing drosophila fruit waste.

Authors

Ralph Noble and Andreja Dobrovin-Pennington