Chill Newsletter | Week commencing 29 June

Morning All,

Other than the unseasonally warm day on the 23/6/25 chill has been accumulating nicely over the past week. Griffith is starting to get cooler but my concern here is that it is a long way behind where it would normally be which affect those crops that are grown specifically in that region (prunes and cherries). Chill accumulation in Griffith this season is something that I have not seen before and at this stage one would lean towards plants behaving similar to the Riverland.

The big difference is in Swan Hill which is dealing with some interesting issues regarding chill

• Chill hours are looking positive;
• The delay in the start to chill will gain insight into the length of the vernalisation period in conjunction with chill unit accumulation and bud fertility;
• 3-4 warm days should see some bud movement in most almonds and the medium low chill stone fruit varieties;
• Expect to see early bud movements in grapes

For the Riverland there is probably another 10-12 days to accumulate the same amount of chill as seen in Swan Hill.

Then the complicating factor is throwing in Met Bureau data and then realising that you can not make decisions on the long-term forecasts. The original forecast was for a very warm winter. So far, we have had a very warm May, but June has been very cold and if looking at the 30-day forecast there is nothing that suggests that we are going to have a bud breaking event during the 18-23^rd July at this stage.

The real key emerging to this season’s chill will be what happens with temperatures in August. Following the 14-day cycle appears to be reasonably close in estimations of chill. If the weather remains dry and for SA, the short-term forecast is for not very much rain and if warm conditions arise bud movement around these weather conditions are most likely.

For growers using Dormex timing will be critical for several reasons:

• Late start to chill;
• Has the tree acquired the length of vernalisation (not just total chill hours) prior to applications of dormancy breakers;
• Do you go later and apply products at lower rates to ensure both chill and dormancy length;

 I have no idea what people now mean when they talk about an average season, I think it means the one that never happens.

‍

Regards,

Shane Phillips | Head Chemist - Research & Development

E: shane.phillips@biocentral-labs.com

‍

Stay connected and receive updates, resources and insights—subscribe to our newsletter today.

‍