With the recent rain events that have occurred over the last few days and an increased risk of bunch rots developing now is the time to examine risk factors and symptoms
- Tight bunches and berries splitting from excessive water uptake may allow various rots to become established. Insect or mechanical damage can also provide opportunities for fungi and bacteria to establish when free moisture is around.
- Increased humidity in bunch zone increases chances of bunch rots developing and promotes further infections.
- Dense canopies will cause restricted airflow, allowing for increased humidity in the microclimate around the fruit and delay the natural drying out after the rainfall.
Even though there is very little that can be done during this period, the following should be applied:
- Careful monitoring of blocks to watch for signs of botrytis and other rots. As a minimum check known disease hotspots (eg high vigour zones (dense canopies), stressed vines (sunburnt fruit).
- Trimming: to open canopies up to maximise airflow, but ensure there is enough canopy to protect fruit from excessive sunburn.
- Contact GLOs of contracting wineries to let them know there may be a problem developing in the block. This may lead to fruit coming off early or as soon as possible to limit the damage.
- Coverage may not be achievable at this point with tight bunches and denser canopies.
- Fungicides with Iprodione (ensure water is buffered) have a seven day WHP which can be used for preventative botrytis control. PMS (also buffered) and other drying agents (Peratec) may also be considered for desiccation of split berries/ disease suppression. Your contracting winery should be contacted prior to application of any of these products. Total fruit coverage may not be achievable at this point with tight bunches and denser canopies.