IThe critical phases for disease control are during flowering and fruit set, and after harvest. This disease is most severe during wet weather when new growth flushes are particularly susceptible.
The leaf spot symptom is generally not serious enough to warrant treatment or preventative measures. However, prevention against the fruit rot symptom requires regular spraying and orchard hygiene.
Pre-harvest treatment
Follow a recommended fungicide spray program for your crop from flowering to fruit set. Control fruit-damaging pests such as fruitspotting bug and fruit fly. Pay attention to orchard hygiene by pruning out dead wood before flowering, and regularly removing infected fruit and dead leaves entangled in the canopy. Keeping the canopy open by judiciously pruning and tree shaping helps to reduce the severity of infection. Use regular leaf and soil analyses to keep nutrient levels, particularly calcium and nitrogen, at adequate levels, as this increases the resistance of the fruit to infection. Avoid planting susceptible varieties.
In annual crops, do not plant into soil containing plant residue from a previous susceptible crop. Follow a recommended fungicide spray program and do not save seed from an infected crop.
Post-harvest treatment
Treat fruit after harvest with an appropriate chemical. Pre-cool fruit before transport if the time from harvest to delivery at the wholesale market exceeds two days. Store fruit until sale at the temperature recommended for that crop. The longer the period between harvesting and consumption the worse the disease, so minimise delays in marketing wherever possible.
Handle fruit carefully to avoid damage that can initiate the onset of the disease.
To minimise degreening burn in citrus avoid picking immature fruit and carefully manage the degreening duration, temperature and ethylene concentration. Also avoid over-fertilising with nitrogen fertiliser and maintain even soil moisture close to harvest.