Blastobasis often goes unnoticed until harvest when the damage is done and it is too late to take remedial action for the current season. Insecticidal controls need to be timed to control caterpillars as they hatch from eggs.
- The flight and egg hatch of blastobasis coincides approximately with that of the first generation of codling moth, so sprays times for codling moth that are effective against Blastobasis should control both pests.
- Chlorantraniliprole (Coragen) offers incidental control of blastobasis when applied for Codling moth control. For best fruit protection, it should be applied during egg-laying at the ‘ovicide’ timing, before egg-hatch and fruit penetration occurs.
- Pyriproxyfen (Harpun) is approved for use on apples to control codling moth and may offer incidental control of blastobasis. It inhibits egg hatch, metamorphosis of nymphs to adults and reduces the fecundity of adult females. However, as a new product to the UK in 2020, further experience of its use is required to inform growers and agronomists of its efficacy at controlling blastobasis.
- It is probable that indoxacarb (Steward or Explicit) is also effective.
- The insecticidal protection should be maintained continuously by spraying a suitable insecticide at 2-3 week intervals from 1 week after the start of the flight period until 2-3 weeks after the end of the flight period, remembering that the maximum number of applications of any insecticide used.
- Bacillus thuringiensis has little activity against blastobasis.
- Synthetic pyrethroids are highly effective but their use should be avoided because they are harmful to the orchard predatory mite Typhlodromus pyri.
- It should be noted that the use of the sex pheromone mating disruption system RAK 3+4 for codling moth and summer fruit tortrix moth control, fails to control blastobasis, so careful monitoring should continue for blastobasis with this system and be prepared to use specific control measures.
Insecticide resistance
Resistance of blastobasis to insecticides is not known to occur but has not been investigated.