Tuesday, 23 March 2021
Scott Raffle explains how new research could reduce our reliance on spray products to control codling and tortrix moths. It may also prevent the pest overwintering and help avoid new attacks the following year.
Growers traditionally rely upon conventional spray control products to reduce populations of codling and tortrix moths to levels that are not damaging to apple and pear crops. However, the numbers of these pests that overwinter are still sufficiently high to instigate new attacks the following season. We, therefore, need a new strategy to reduce our reliance on spray products and help avoid new attacks each year.
Mating disruption and predatory nematodes
We assessed novel sex pheromone mating disruption techniques, along with the use of predatory nematodes, to improve control and avoid repeated use of conventional spray products.
The sex pheromone mating disruption product RAK 3&4 provided similar control of codling, fruit tree tortrix and summer fruit tortrix moths when compared to conventional spray programmes in field trials. However, it did not provide complete control. It may be necessary to use additional sprays if monitoring trap catches of moth pests exceed damage thresholds. This may be especially important in early ripening apples and pears, which are more vulnerable to the pests.
Initial trials demonstrated that codling moth larvae are susceptible to a mix of predatory nematodes (Steinernema carpocapsa and Steinernema feltiae). However, the pupae are less susceptible and further field trials are required to repeat these results.
As RAK 3&4 is specific to codling and tortrix moths, if you are not using lepidoptera control agents, populations of other moth pests such as Blastobasis lacticollela can increase. In this work, we identified a female sex pheromone of blastobasis, but could not attract males.
Recommendations to prevent, detect and control codling and tortrix moths
- Use mating disruption technology
Using mating disruption technology can reduce your reliance on conventional spray programmes. Where pest pressure is medium to high, be prepared to apply an additional spray to early ripening or vulnerable apple and pear cultivars.
- Monitor closely for other pests
In particular, look out for tortrix species and blastobasis caterpillars, which may occur due to limited use of lepidopteran control products.
Even if you have no previous experience of blastobasis in orchards, it would be wise to continue to monitor as populations may build up locally over the years.
Scott has worked for AHDB for 11 years, having spent three years at HDC and 30 years in the fruit industry in total. Prior to his time at AHDB, Scott was a fruit advisor/agronomist for 16 years with ADAS, specialising in soft fruit and apple and pear storage.